Sample records for bahrelghazali mio-pliocene hominids

  1. Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad.

    Lebatard, Anne-Elisabeth; Bourlès, Didier L; Duringer, Philippe; Jolivet, Marc; Braucher, Régis; Carcaillet, Julien; Schuster, Mathieu; Arnaud, Nicolas; Monié, Patrick; Lihoreau, Fabrice; Likius, Andossa; Mackaye, Hassan Taisso; Vignaud, Patrick; Brunet, Michel


    Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16 degrees 00'N, 18 degrees 53'E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16 degrees 15'N, 17 degrees 29'E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronological estimation of the hominid remains: early Pliocene (3-3.5 Ma) at KT 12 and late Miocene ( approximately 7 Ma) at TM 266. Atmospheric (10)Be, a cosmogenic nuclide, was used to quasicontinuously date these sedimentary units. The authigenic (10)Be/(9)Be dating of a pelite relic within the sedimentary level containing Abel yields an age of 3.58 +/- 0.27 Ma that points to the contemporaneity of Australopithecus bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 (10)Be/(9)Be ages obtained within the anthracotheriid unit containing Toumaï bracket, by absolute dating, the age of Sahelanthropus tchadensis to lie between 6.8 and 7.2 Ma. This chronological constraint is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock. PMID:18305174

  2. Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad

    Lebatard, Anne-Elisabeth; Bourlès, Didier L.; Duringer, Philippe; Jolivet, Marc; Régis BRAUCHER; Carcaillet, Julien; Schuster, Mathieu; Arnaud, Nicolas; Monié, Patrick; Lihoreau, Fabrice; Likius, Andossa; Mackaye, Hassan Taisso; Vignaud, Patrick; Brunet, Michel


    Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16°00′N, 18°53′E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15′N, 17°29′E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronologic...




    Full Text Available There are few previous references to fossil crustaceans for the Neogene marine layers of the Canary Islands (Spain. The Mio-Pliocene marine sedimentary layers in the eastern islands (Gran Canaria, Fuerteventura and Lanzarote were previously characterised by the presence of numerous fossil fauna, mainly anthozoans and molluscs, which correspond to an equatorial-typepalaeoclimate, warmer than the present climate. This Mio-Pliocene transition dated between 9.3 and 4.1 Ma. In this paper, 12 fossil crustacean taxa are identified and classified, including decapods and barnacles: Balanus concavus Bronn, 1831, Balanus spongicola Brown, 1827, Balanus perforatus Bruguière, 1789, Chenolobia testudinaria Linnè, 1767, Tetraclita cf. rubescens Darwin, 1854, Callianassa matsoni Rathbun, 1935, Callianassa sp., Upogebia sp, Eriphia aff. verrucosa (Forskal, 1775 , Maja sp., Scylla michelini Milne-Edwards, 1861 and Ocypode sp. Some of these taxa mean new references for the Atlantic islands and the North African Atlantic and definitely enlarge the palaeographic distribution of Neogene crustaceans beyond the Mediterranean region, extending it to the North Atlantic. Particularly significant are the presence of Tetraclita cf. rubescens ,this being the first reported fossil occurrence of this barnacle outside the North America Pacific coasts, and Chenolobia testudinaria , indicating for the first time the existence of marine turtles in these islands during the Neogene. These results are coherent with previous research hypothesising the existence of a flow of surface water between the Pacific and Atlantic in the Mio-Pliocene transition (Central American Seaway, CAS which explains the arrival of organisms, in larval stage, from Central America to the Canary Islands.

  4. Evidence for long-term uplift on the Canary Islands from emergent Mio Pliocene littoral deposits

    Meco, Joaquín; Scaillet, Stéphane; Guillou, Hervé; Lomoschitz, Alejandro; Carlos Carracedo, Juan; Ballester, Javier; Betancort, Juan-Francisco; Cilleros, Antonio


    Several islands in the Canarian archipelago show marine deposits with identical fossil faunas, which are generally assigned to different glacioeustatic marine episodes: mainly Pleistocene episodes in Lanzarote and Fuerteventura, and Mio-Pliocene ones in Gran Canaria. Three fossil species ( Saccostrea chili, Nerita emiliana and Strombus coronatus) characterize all the marine deposits from southern Lanzarote, to the west and south of Fuerteventura and northeast of Gran Canaria. Three other species ( Ancilla glandiformis, Rothpletzia rudista and Siderastraea miocenica) confirm the chronostratigraphic attribution of these deposits. Other more occasional fossils (as Chlamys latissima, Isognomon soldanii and Clypeaster aegyptiacus) fit an upper Miocene and lower Pliocene age. This agrees with new K/Ar ages obtained from pillow lavas emplaced into the marine deposits (ca. 4.1 Ma in Gran Canaria, ca. 4.8 Ma in Fuerteventura) and from underlying (ca. 9.3 Ma in Gran Canaria) or overlying (ca. 9.8 Ma in Lanzarote) lava flows. The marine deposits are eroded but large continuous segments are preserved sloping gently towards the coast. Variations in the highest and the lowest elevations of the deposits apsl (above present sea level) indicate post-depositional uplift movements. Glacioeustatic causes are unlikely to be responsible for these variations on the basis of the coastal location of the deposits and their equatorial fauna characteristic of Mio-Pliocene corals. Differential uplift of the deposits across the archipelago is argued to result from the progressive seaward tilting of the islands along the insular volcanic trail marking the westward migration of hot spot head since 20 Ma. Successive westward accretion of younger volcanic edifices resulted in increasing lithostatic load of the crust with progressive (diachronous) tilting of the older edifices and their palaeo-shorelines marked by past coastal deposits.

  5. Giant bunodont Lutrinae from the Mio-Pliocene of Kenya and Uganda

    Pickford, M.


    Full Text Available Three new species of bunodont otters are described from the Mio-Pliocene of East Africa. They are provisionally attributed to the genus Sivaonyx Pilgrim, 1931. The species described are Sivaonyx soriae, nov. sp. and Sivaonyx senutae nov. sp. from the Latest Miocene Lukeino Formation (Kenya and Sivaonyx kamuhangirei nov. sp. from the Pliocene of Kazinga and Warwire (Uganda. Additional material of the species Sivaonyx ekecaman (Werdelin, 2003 is described from Sagatia, Mabaget Formation (Kenya. The systematics of the new tribe Enhydriodontini are discussed and we report the presence of evolutionary tendencies in the bunodont African otters: increase in body size, modification of the carnassial teeth. In particular in the P4/ the protocone becomes well separated from the paracone, at the same time that an anterior valley develops.Se describen tres nuevas especies de nutrias bunodontas del Mio-plioceno de Africa oriental. Provisionalmente se adscriben al género Sivaonyx Pilgrim 1931. Las especies descritas son Sivaonyx soriae nov. sp y Sivaonyx senutae nov. sp. del Mioceno final de la formación Lukeino (Kenia, y Sivaonyx kamuhangirei nov. sp del Plioceno de Kazinga y Warwire (Uganda. También se describen nuevos fósiles de Sagatia, formación Magabet (Kenia atribuibles a la especie Sivaonyx ekecaman (Werdelin, 2003. Se discute la sistemática de la nueva tribu Enhydriotini y se señala la presencia de dos tendencias evolutivas en las nutrias bunodontas africanas: incremento de talla y modificación de las carniceras. Especialmente del P4/ en el que el protocono se va separando del paracono, al mismo tiempo que se desarrolla un valle en posición anterior.

  6. Depositional Environment of Mio-Pliocene Siwalik Sedimentary Strata from the Darjeeling Himalayan Foothills, India: A Palynological Approach

    More, Sandip; Paruya, Dipak Kumar; Taral, Suchana; Chakraborty, Tapan; Bera, Subir


    A rich and diverse palynoassemblage recovered from the Churanthi River section (26°53' 59.3" N, 88°34' 17.2" E), Darjeeling foothills Eastern Himalaya, has yielded 87 species assigned to 69 genera. The palynoassemblage is rich in angiosperm taxa (45.63%) followed by gymnosperms (0.45%), pteridophytes (18.49%) and fungal remains (23.88%). Based on their nearest living relatives, a wet evergreen to semi-evergreen forest under a humid tropical to sub-tropical environment during the Mio-Pliocene age has been suggested. A lot of angiosperms such as Palaeosantalaceaepites, Araliaceoipollenites, Malvacearampollis, Zonocostites, Neocouperipollis, Dicolpopollis, Palmidites, Palmaepollenites, isolated salt glands of mangrove plant leaves (Heliospermopsis) and Mediaverrunites type of fungal spores, along with ichnofossils like Planolites, Palaeophycus, Skolithos, Rosselia, Ophiomorpha and Teichichnus associated with rippled mudstone-siltstone suggest an environment strongly influenced by brackish water. Primary sedimentary structures in the associated strata indicate strong wave agitation common in shallow marine setting. Some high elevation components (5.14%) such as Alnipollenites, cf. Corylus (Betulaceae), Juglanspollenites, Engelhardtioipollenites (Juglandaceae), Quercoides, Cupuliferoidaepollenites, Lithocarpus, Castanopsis (Fagaceae), Abietineaepollenites (Pinaceae) represent hinterland vegetation possibly transported to the prograding deltaic coastline by the rivers. Reworked palynotaxa (Striatopodocarpites sp., Striatites sp., Faunipollenites sp., Circumstriatites sp., Crescentipollenites sp., Cuneatisporites sp., Parasaccites sp., Scheuringipollenites sp., Rhizomaspora sp., Marsupipollenites sp., Lophotriletes sp.) of Permian age have also been recorded in the palynoassemblage (11.55%) indicating the abundance of Permian Gondwana strata in the source area. PMID:26930664

  7. Revised Chronology for the Mio-Pliocene Successions of the Eastern Paratethys: Towards a Better Understanding of Paleoenvironmental Change

    Krijgsman, W.; Chang, L.; Baak, C. V.; Palcu, D.; Vasiliev, I.


    Paratethys is a large epicontinental sea, stretching from Germany to China at the beginning of the Oligocene (~34 Myr ago), that progressively retreated by a complex combination of basin infill, glacio-eustatic sea-level lowering and tectonic uplift to its present-day remnants: Black Sea, Caspian Sea and Aral Lake. Paratethys experienced major paleoenvironmental changes towards anoxic, hypersaline, and fresh water conditions. An accurate geological time scale (GTS) is crucial to understand the timing and rates of these change and to determine the underlying mechanisms. Geological time scales for the Paratethys region are notoriously controversial and encompass mainly regional stages, which are all defined on the basis of characteristic faunal assemblages (mainly mollusks and ostracods) endemic to the Paratethys Sea. During the last decade, we have performed numerous integrated magneto-biostratigraphic studies on the Mio-Pliocene sedimentary successions of the Eastern Paratethys, which resulted in revised chronological frameworks for the Dacian, Black Sea and Caspian Sea basins. This allows high-resolution stratigraphic correlations between the individual Paratethys subbasins and with the Mediterranean successions and help to better understand the dramatic paleoenvironmental changes in the region, such as the Messinian Salinity Crisis. Rock magnetic analyses of the sedimentary sequences of the Paratethys indicate that greigite is the main magnetic carrier and that a range of magnetic properties cannot be explained by the presence of diagenetic greigite, but are instead consistent with those expected for a biogenetic (bacterial) origin.

  8. Depositional Environment of Mio-Pliocene Siwalik Sedimentary Strata from the Darjeeling Himalayan Foothills, India: A Palynological Approach.

    More, Sandip; Paruya, Dipak Kumar; Taral, Suchana; Chakraborty, Tapan; Bera, Subir


    A rich and diverse palynoassemblage recovered from the Churanthi River section (26°53' 59.3" N, 88°34' 17.2" E), Darjeeling foothills Eastern Himalaya, has yielded 87 species assigned to 69 genera. The palynoassemblage is rich in angiosperm taxa (45.63%) followed by gymnosperms (0.45%), pteridophytes (18.49%) and fungal remains (23.88%). Based on their nearest living relatives, a wet evergreen to semi-evergreen forest under a humid tropical to sub-tropical environment during the Mio-Pliocene age has been suggested. A lot of angiosperms such as Palaeosantalaceaepites, Araliaceoipollenites, Malvacearampollis, Zonocostites, Neocouperipollis, Dicolpopollis, Palmidites, Palmaepollenites, isolated salt glands of mangrove plant leaves (Heliospermopsis) and Mediaverrunites type of fungal spores, along with ichnofossils like Planolites, Palaeophycus, Skolithos, Rosselia, Ophiomorpha and Teichichnus associated with rippled mudstone-siltstone suggest an environment strongly influenced by brackish water. Primary sedimentary structures in the associated strata indicate strong wave agitation common in shallow marine setting. Some high elevation components (5.14%) such as Alnipollenites, cf. Corylus (Betulaceae), Juglanspollenites, Engelhardtioipollenites (Juglandaceae), Quercoides, Cupuliferoidaepollenites, Lithocarpus, Castanopsis (Fagaceae), Abietineaepollenites (Pinaceae) represent hinterland vegetation possibly transported to the prograding deltaic coastline by the rivers. Reworked palynotaxa (Striatopodocarpites sp., Striatites sp., Faunipollenites sp., Circumstriatites sp., Crescentipollenites sp., Cuneatisporites sp., Parasaccites sp., Scheuringipollenites sp., Rhizomaspora sp., Marsupipollenites sp., Lophotriletes sp.) of Permian age have also been recorded in the palynoassemblage (11.55%) indicating the abundance of Permian Gondwana strata in the source area. PMID:26930664

  9. Petrogenesis of the Eocene and Mio Pliocene alkaline basaltic magmatism in Meseta Chile Chico, southern Patagonia, Chile: Evidence for the participation of two slab windows

    Espinoza, Felipe; Morata, Diego; Pelleter, Ewan; Maury, René C.; Suárez, Manuel; Lagabrielle, Yves; Polvé, Mireille; Bellon, Hervé; Cotten, Joseph; De la Cruz, Rita; Guivel, Christelle


    The Meseta Chile Chico (MCC, 46.4°S) is the westernmost exposure of Eocene (lower basaltic sequence, LBS; 55-40 Ma, K-Ar ages) and Mio-Pliocene (upper basaltic sequence, UBS; 16-4 Ma, K-Ar ages) flood basalt volcanism in Patagonia. The MCC is located south of the Lago General Carrera-Buenos Aires (LGCBA), southeast from the present day Chile Triple Junction (CTJ), east of the actual volcanic gap between Southern South Volcanic Zone and Austral Volcanic Zone (SSVZ and AVZ, respectively) and just above the inferred location of the South Chile Ridge segment subducted at ˜6 Ma (SCR-1). Erupted products consist of mainly ne-normative olivine basalt with minor hy-normative tholeiites basalt, trachybasalt and basanite. MCC lavas are alkaline (42.7-53.1 wt.% SiO 2, 3-8 wt.% Na 2O+K 2O) and relatively primitive (Ni: 133-360 ppm, Cr: 161-193 ppm, Co: 35-72 ppm, 4-16.5 MgO wt.%). They have a marked OIB-like signature, as shown by their isotopic compositions ( 87Sr/ 86Sr o=0.70311-0.70414 and ɛNd=+4.7-+5.1) and their incompatible trace elements ratios (Ba/La=10-20, La/Nb=0.46-1.09, Ce/Pb=15.52-27.5, Sr/La1, Sr/La>25, low Ce/Pb, Nb/U) compatible with contamination by arc/slab-derived and/or crustal components. We propose that the genesis and extrusion of magmas is related to the opening of two slab windows due to the subduction of two active ridge segments beneath Patagonia during Eocene and Mio-Pliocene.

  10. Symphyseal shape variation in extant and fossil hominoids, and the symphysis of Australopithecus bahrelghazali.

    Guy, Franck; Mackaye, Hassane-Taïsso; Likius, Andossa; Vignaud, Patrick; Schmittbuhl, Matthieu; Brunet, Michel


    The holotype of the species Australopithecus bahrelghazali is a mandibular fragment preserving left C-P(4) and right I(2)-P(4). One of the key features of the A. bahrelghazali mandible is its sagittally and transversally flat anterior region associated with a vertical, bulbous symphysis that is assumed to differ morphologically from the classic, more apelike eastern australopith morphology with its sloping symphysis, developed transverse tori, and distinct genioglossal fossa. Yet, close similarity has been suggested between A. bahrelghazali and A. afarensis. To date, no metrical comparison of the symphyseal morphology of east and west African australopiths has been performed. For the selected characters, this study attempts to test the following null hypothesis: A. bahrelghazali does not present significant differences from A. afarensis (i.e., A. bahrelghazali vs. A. afarensis variation does not depart from expected intraspecific variation for hominoid species). Analysis of the mandibular symphysis is difficult to undertake using conventional linear variables since few landmarks are available to make a precise quantitative assessment of its morphology. In addition, while a few studies have used outline-based techniques of analysis to address symphyseal shape variation, none has integrated data on early hominins. We present here a detailed comparative study of variation in the symphyseal outline of A. bahrelghazali and A. afarensis based on a quantitative characterization by elliptic Fourier coefficients. Original data on symphyseal variation in Pliocene hominins are provided and discussed within a comparative framework of extant and fossil hominoid representatives. We evaluate the relevance of our quantitative data describing the shape of the symphysis for discriminating hominoid taxa, and test for differences in symphyseal shape between A. bahrelghazali and A. afarensis. Elliptic Fourier coefficients appear to be well-suited descriptors for depicting symphyseal

  11. Cranial morphometry of early hominids: facial region.

    Bilsborough, A; Wood, B A


    We report here on early hominid facial diversity, as part of a more extensive morphometric survey of cranial variability in Pliocene and early Pleistocene Hominidae. Univariate and multivariate techniques are used to summarise variation in facial proportions in South and East African hominids, and later Quaternary groups are included as comparators in order to scale the variation displayed. The results indicate that "robust" australopithecines have longer, broader faces than the "gracile" form, but that all australopithecine species show comparable degrees of facial projection. "Robust" crania are characterised by anteriorly situated, deep malar processes that slope forwards and downwards. Smaller hominid specimens, formally or informally assigned to Homo (H. habilis, KNM-ER 1813, etc.), have individual facial dimensions that usually fall within the range of Australopithecus africanus, but which in combination reveal a significantly different morphological pattern; SK 847 shows similarly hominine facial proportions, which differ significantly from those of A. robustus specimens from Swartkrans. KNM-ER 1470 possesses a facial pattern that is basically hominine, but which in some respects mimics that of "robust" australopithecines. Early specimens referred to H. erectus possess facial proportions that contrast markedly with those of other Villafranchian hominids and which suggest differing masticatory forces, possibly reflecting a shift in dietary niche. Overall the results indicate two broad patterns of facial proportions in Hominidae: one is characteristic of Pliocene/basal Pleistocene forms with opposite polarities represented by A. boisei and H. habilis; the other pattern, which typifies hominids from the later Lower Pleistocene onwards, is first found in specimens widely regarded as early representatives of H. erectus, but which differ in which certain respects from the face of later members of that species. PMID:3136656

  12. Dating of fossil hominid: problems and perspectives

    The hominid dating anterior to the Homo Erectus has been based up to now on the rocks and minerals geochronology of vulcanic origem in stratigraphic relation with the fossils. Two methods are widely used, potassium-argon and uranium fission track dating. The vulcanic material dating; lava, lephra, associated with the hominid leavings show big difficults essentially connected to several types of contamination and modification. Two available examples inside the east-african rift show the probelms linked to these dating. The current progresses in the dating methods can contribute by one hand to a better utilization of the K-Ar and fisson track methods for the vulcanic materials. By other hand, with the introduction of new dating methods (thermoluminescence and electron paramagnetic resonance) will be possible to date directly whether the fossil bone itself or the associated sedimentar material. This open new perspectives in particular for every sites which are not inter-stratified with the vulcanic material. (L.C.)

  13. Modelling the locomotor energetics of extinct hominids.

    Kramer, P A


    Bipedality is the defining characteristic of Hominidae and, as such, an understanding of the adaptive significance and functional implications of bipedality is imperative to any study of human evolution. Hominid bipedality is, presumably, a solution to some problem for the early hominids, one that has much to do with energy expenditure. Until recently, however, little attention could be focused on the quantifiable energetic aspects of bipedality as a unique locomotor form within Primates because of the inability to measure empirically the energy expenditure of non-modern hominids. A recently published method provides a way of circumventing the empirical measurement dilemma by calculating energy expenditure directly from anatomical variables and movement profiles. Although the origins of bipedality remain clouded, two discernible forms of locomotor anatomy are present in the hominid fossil record: the australopithecine and modern configurations. The australopithecine form is best represented by AL 288-1, a partial skeleton of Australopithecus afarensis, and is characterized as having short legs and a wide pelvis. The modern form is represented by modern humans and has long legs and a narrow pelvis. Human walking is optimized to take advantage of the changing levels of potential and kinetic energy that occur as the body and limbs move through the stride cycle. Although this optimization minimizes energy expenditure, some energy is required to maintain motion. I quantify this energy by developing a dynamic model that uses kinematic equations to determine energy expenditure. By representing both configurations with such a model, I can compare their rates of energy expenditure. I find that the australopithecine configuration uses less energy than that of a modern human. Despite arguments presented in the anthropological literature, the shortness of the legs of AL 288-1 provides no evidence that she was burdened with a compromised or transitional locomotor anatomy

  14. Aquatic ape theory and fossil hominids.

    Verhaegen, M J


    While most older palaeo-anthropological studies emphasise the similarities of the fossil hominids with modern man, recent studies often stress the unique and the apelike features of the australopithecine dentitions, skulls and postcranial bones. It is worth reconsidering the features of Australopithecus, Homo erectus and Homo neanderthalensis in the light of the so-called Aquatic Ape Theory (AAT) of Hardy and Morgan, and to compare the skeletal parts of our fossil relatives with those of (semi)aquatic animals. Possible convergences are observed with proboscis monkeys, beavers, sea-otters, hippopotamuses, seals, sea-lions, walruses, sea-cows, whales, dolphins, porpoises, penguins and crocodiles. PMID:1909768

  15. [The endocranial parietal vascular traces in the hominid line].

    Saban, R


    The study of the grooves traced by the middle meningeal veins on the parietal bone or the endocast of Hominid fossils shows different patterns which correspond to each evolutive stage. Height types are characterised among the Hominids (Australopithecines, Archanthropines, Paleanthropines and Neanthropines): I, robust Australopithecine type; II, gracile Australopithecine type; III, earliest Pithecanthropine type; IV, evolved Pithecanthropine type; V, Preneandertal type; VI, neandertal type; VII, Neanthropine type; VIII, modern type. PMID:405108

  16. Widespread Genomic Signatures of Natural Selection in Hominid Evolution

    McVicker, Graham; Gordon, David; Davis, Colleen; Green, Phil


    Selection acting on genomic functional elements can be detected by its indirect effects on population diversity at linked neutral sites. To illuminate the selective forces that shaped hominid evolution, we analyzed the genomic distributions of human polymorphisms and sequence differences among five primate species relative to the locations of conserved sequence features. Neutral sequence diversity in human and ancestral hominid populations is substantially reduced near such features, resultin...

  17. A reappraisal of early hominid phylogeny.

    Strait, D S; Grine, F E; Moniz, M A


    We report here on the results of a new cladistic analysis of early hominid relationships. Ingroup taxa included Australopithecus afarensis, Australopithecus africanus, Australopithecus aethiopicus, Australopithecus robustus, Australopithecus boisei, Homo habilis, Homo rudolfensis, Homo ergaster and Homo sapiens. Outgroup taxa included Pan troglodytes and Gorilla gorilla. Sixty craniodental characters were selected for analysis. These were drawn from the trait lists of other studies and our own observations. Eight parsimony analyses were performed that differed with respect to the number of characters examined and the manner in which the characters were treated. Seven employed ordered characters, and included analyses in which (1) taxa that were variable with respect to a character were coded as having an intermediate state, (2) characters with variable states in any taxon were excluded; (3) a variable taxon was coded as having the state exhibited by the majority of its hypodigm, (4) variable taxa were coded as missing data for that character, (5) some characters were considered irreversible, (6) masticatory characters were excluded, and (7) characters whose states were unknown in some taxa were excluded. In the final analysis, (8) all characters were unordered. All analyses were performed using PAUP 3.0s. Despite the fact that the eight analyses differed with respect to methodology, they produced several consistent results. All agreed that the "robust" australopithecines form a clade, A. afarensis is the sister taxon of all other hominids, and the genus Australopithecus, as conventionally defined, is paraphyletic. All eight also supported trees in which A. africanus is the sister taxon of a joint Homo+ "robust" clade, although in one analysis an equally parsimonious topology found A. africanus to be the sister of the "robust" species. In most analyses, the relationships of A. africanus and H. habilis were unstable, in the sense that their positions vary in trees

  18. New fission-track ages of mio-pliocene tuffs in the Sierras Pampeanas and Precordillera of Argentina

    Fission-track dates were determined for 18 volcanic tuff horizons located in nine Neogene foreland basin sequences distributed throughout the Precordillera and Sierras Pampeanas of Northwestern Argentina, an area of nearly horizontal subduction. These and other data indicate that a lower age limit for the sedimentary sequences studied is approximately 17 Ma. Therefore these fission-track dates constrain both the history of volcanic activity and the time of deposition in several foreland basins from the middle Miocene to Recent. Although the dates range from 3.6±0.8 Ma to 17.0±1.9 Ma, there is a marked increase in the number of ashes younger than 9 Ma. This implies that two distinct episodes of volcanic activity affected the region. The source of some of these tuffs is unknown but they are probably limited to the 'flat-slab' region between 27 deg and 32 deg S. Tuffs at Rio Blanco and Santa Florentina that are spatially associated with the Mogotes dacite domes of the Famatina Range represented magmatism bracketed from about 7 to 4 Ma in the region underlain by the flat-subducted plate. The stratigraphic relations in the basins show that the faulting that uplifted Sierra de Famatina was contemporaneous with the volcanism which reached the surface along the bounding faults. (Author)

  19. Hydrogen isotopes on organic compounds express large hydrological changes in the Mio-Pliocene of the Dacian Basin (Romania)

    Vasiliev, Iuliana; Reichart, Gert-Jan; Krijgsman, Wout


    During the late Miocene to Pliocene (˜11 to 3 Ma) large part of the southern Eurasian interior was covered by the Eastern Paratethys epicontinental sea. The western most part of the Eastern Paratethys was occupied by the Dacian Basin, in the foredeep of the Carpathians. The active subsidence in the front of the Carpathians led to the fast accumulation of up to 10 km think sedimentary load in the Dacian Basin, all during the latest Miocene and Pliocene. These deposits are now tilted and well exposed along river section in the Carpathian Foredeep. Here we are reconstructing the large-scale changes of hydrologic budget in the Dacian Basin area over a long time interval (8 to 2.5 Ma). The sampled Rîmnicu S\\varat Valley section covers the Messinian salinity crisis interval, times when the adjacent Mediterranean basin suffered severe restrictions of its connections to the Ocean and, subsequently was flooded by the Atlantic at the beginning of Pliocene. We are using compound-specific hydrogen isotopic composition (δD) measured on n-alkanes produced by plant waxes. We focus our analysis on long-chained δDn‑alkanes (n-C27 to n-C33) derived from the vascular plant waxes. The saturated hydrocarbon fraction of the extractable organic matter identified in the a-polar fraction of Rîmnicu S\\varat Valley is dominated by a homologous series of n-alkanes ranging from n-C16 to n-C35. The long-chain (>C25), predominantly odd-carbon number homologues are prevailing which is typical for terrestrial higher plant derived n-alkanes, indicating an important terrestrial organic matter input. The ˜ 60 ‰ amplitude of changes for seven consecutive sampled levels measured from both δDn-C17‑21 and δDn-C27‑31 can be majorly explained by significant changes in the stable hydrogen isotope ratios characterizing the Dacian basin waters and the meteoric waters reaching the Dacian Basin. This indicates that the hydrological regime in Dacian paleo-basin has significantly varied, with heaviest δD values being recorded from a time-interval corresponding to the exceptionally dry Messinian salinity crisis of the Mediterranean.

  20. Sawfishes and Other Elasmobranch Assemblages from the Mio-Pliocene of the South Caribbean (Urumaco Sequence, Northwestern Venezuela)


    The Urumaco stratigraphic sequence, western Venezuela, preserves a variety of paleoenvironments that include terrestrial, riverine, lacustrine and marine facies. A wide range of fossil vertebrates associated with these facies supports the hypothesis of an estuary in that geographic area connected with a hydrographic system that flowed from western Amazonia up to the Proto-Caribbean Sea during the Miocene. Here the elasmobranch assemblages of the middle Miocene to middle Pliocene section of the Urumaco sequence (Socorro, Urumaco and Codore formations) are described. Based on new findings, we document at least 21 taxa of the Lamniformes, Carcharhiniformes, Myliobatiformes and Rajiformes, and describe a new carcharhiniform species (†Carcharhinus caquetius sp. nov.). Moreover, the Urumaco Formation has a high number of well-preserved fossil Pristis rostra, for which we provide a detailed taxonomic revision, and referral in the context of the global Miocene record of Pristis as well as extant species. Using the habitat preference of the living representatives, we hypothesize that the fossil chondrichthyan assemblages from the Urumaco sequence are evidence for marine shallow waters and estuarine habitats. PMID:26488163

  1. Sawfishes and Other Elasmobranch Assemblages from the Mio-Pliocene of the South Caribbean (Urumaco Sequence, Northwestern Venezuela.

    Jorge D Carrillo-Briceño

    Full Text Available The Urumaco stratigraphic sequence, western Venezuela, preserves a variety of paleoenvironments that include terrestrial, riverine, lacustrine and marine facies. A wide range of fossil vertebrates associated with these facies supports the hypothesis of an estuary in that geographic area connected with a hydrographic system that flowed from western Amazonia up to the Proto-Caribbean Sea during the Miocene. Here the elasmobranch assemblages of the middle Miocene to middle Pliocene section of the Urumaco sequence (Socorro, Urumaco and Codore formations are described. Based on new findings, we document at least 21 taxa of the Lamniformes, Carcharhiniformes, Myliobatiformes and Rajiformes, and describe a new carcharhiniform species (†Carcharhinus caquetius sp. nov.. Moreover, the Urumaco Formation has a high number of well-preserved fossil Pristis rostra, for which we provide a detailed taxonomic revision, and referral in the context of the global Miocene record of Pristis as well as extant species. Using the habitat preference of the living representatives, we hypothesize that the fossil chondrichthyan assemblages from the Urumaco sequence are evidence for marine shallow waters and estuarine habitats.

  2. Mio-Pliocene magmatism in the Baguio Mining District (Luzon, Philippines): age clues to its geodynamic setting

    The Baguio mining district (Central Cordillera of Luzon Island) has evolved, from Eocene to recent time, from a marginal basin to an island arc setting, related firstly to a westward subduction and after a subduction polarity reversal by the early Miocene to an eastward subduction. Late Miocene to Quaternary magmatism and tectonics have allowed the deposition of gold and copper. This scenario is consistent with available geological field and isotopic K-Ar ages. (authors)

  3. Selective Constraint on Noncoding Regions of Hominid Genomes.


    Full Text Available An important challenge for human evolutionary biology is to understand the genetic basis of human-chimpanzee differences. One influential idea holds that such differences depend, to a large extent, on adaptive changes in gene expression. An important step in assessing this hypothesis involves gaining a better understanding of selective constraint on noncoding regions of hominid genomes. In noncoding sequence, functional elements are frequently small and can be separated by large nonfunctional regions. For this reason, constraint in hominid genomes is likely to be patchy. Here we use conservation in more distantly related mammals and amniotes as a way of identifying small sequence windows that are likely to be functional. We find that putatively functional noncoding elements defined in this manner are subject to significant selective constraint in hominids.

  4. Hand function and tool behavior in early hominids.

    Susman, R L


    Prompted by the discovery of the Olduvai Hominid 7 hand (Homo habilis) in 1960, studies of primate hands were conducted in order to understand better the functional morphology of the earliest hominids and the evolution of tool behavior. Since Napier's work in the early 1960's, the hand bones of a number of other species have been recovered in East and South Africa. New hominid finds and a prolific archaeological record have broadened our perspective on the evolution of tool behavior in Australopithecus, Paranthropus, and early Homo. A debate is underway at this time on the questions of what exactly we can glean from the fossil record regarding the evolution of tool behavior and what are the best approaches to interpreting the evidence. I support the model of Napier that identified morphological correlates of precision and power grasping in the hands of extant primates and in early hominid hand bones. At the same time, I question both the underlying rationale and attempts to identify more subtle aspects of precision grasping, based on present evidence. PMID:9680465

  5. Enamel hypoplasia in the middle pleistocene hominids from Atapuerca (Spain).

    Bermúdez de Castro, J M; Pérez, P J


    The prevalence and chronology of enamel hypoplasias were studied in a hominid dental sample from the Sima de los Huesos (SH) Middle Pleistocene site at the Sierra de Atapuerca (Burgos, northern Spain). A total of 89 permanent maxillary teeth, 143 permanent mandibular teeth, and one deciduous lower canine, belonging to a minimum of 29 individuals, were examined. Excluding the antimeres (16 maxillary and 37 mandibular cases) from the sample, the prevalence of hypoplasias in the permanent dentition is 12.8% (23/179), whereas the deciduous tooth also showed an enamel defect. No statistically significant differences were found between both arcades and between the anterior and postcanine teeth for the prevalence of hypoplasias. In both the maxilla and the mandible the highest frequency of enamel hypoplasias was recorded in the canines. Only one tooth (a permanent upper canine) showed two different enamel defects, and most of the hypoplasias were expressed as faint linear horizontal defects. Taking into account the limitations that the incompleteness of virtually all permanent dentitions imposes, we have estimated that the frequency by individual in the SH hominid sample was not greater than 40%. Most of the hypoplasias occurred between birth and 7 years (N = 18, X = 3.5, SD = 1.3). Both the prevalence and severity of the hypoplasias of the SH hominid sample are significantly less than those of a large Neandertal sample. Furthermore, prehistoric hunter-gatherers and historic agricultural and industrial populations exhibit a prevalence of hypoplasias generally higher than that of the SH hominids. Implications for the survival strategies and life quality of the SH hominids are also discussed. PMID:7785727

  6. Palaeodemography of the Atapuerca-SH Middle Pleistocene hominid sample.

    Bermúdez de Castro, J M; Nicolás, M E


    We report here on the palaeodemographic analysis of the hominid sample recovered to date from the Sima de los Huesos (SH) Middle Pleistocene cave site in the Sierra de Atapuerca (Burgos, Spain). The analysis of the mandibular, maxillary, and dental remains has made it possible to estimate that a minimum of 32 individuals, who probably belonged to the same biological population, are represented in the current SH human hypodigm. The remains of nine-individuals are assigned to males, and nine to females, suggesting that a 1:1 sex ratio characterizes this hominid sample. The survivorship curve shows a low representation of infants and children, a high mortality among the adolescents and prime-age adults, and a low older adult mortality. Longevity was probably no greater than 40 years. This mortality pattern (adolescents and adults); which in some aspects resembles that observed in Neandertals, is quite different from those reported for recent foraging human groups. The adult age-at-death distribution of the SH hominid sample appears to be neither the consequence of underaging the older adults, nor of differential preservation or of the recognition of skeletal remains. Thus if we accept that they had a life history pattern similar to that of modern humans there would appear to be a clear contradiction between the demographic distribution and the demographic viability of the population represented by the SH hominid fossils. The possible representational bias of the SH hominid sample, as well as some aspects of the reproductive biology of the Pleistocene populations are also discussed. PMID:9300346

  7. A hominid tibia from Middle Pleistocene sediments at Boxgrove, UK.

    Roberts, M B; Stringer, C B; Parfitt, S A


    Fossil hominids from the earlier Middle Pleistocene of Europe are very rare and the Mauer mandible is generally accepted as the most ancient, with an estimated age of 500 kyr. We report here on the discovery of a human tibia, in association with stone tools, from calcareous silts at the Lower Palaeolithic site of Boxgrove, West Sussex, UK (Fig. 1). The silt units are correlated by mammalian biostratigraphy to an, as yet unnamed, major temperate stage or interglacial that immediately pre-dates the Anglian cold stage. Accordingly, the temperate sediments are equated with oxygen isotope stage 13 (ref. 6) and are therefore roughly coeval with the Mauer mandible. The massive tibia is the oldest hominid fragment from the British Isles and provides the first information about the manufacturers of the early Acheulian industries of Europe. It is assigned to Homo cf. heidelbergensis. PMID:8183368

  8. Encephalization in hominids: evidence for the model of punctuationalism.

    Hofman, M A


    A progressive enlargement of the hominid brain started 3-2 million years ago, probably from a gracile australopithecine form. Since then, three major transitions in degree of encephalization have taken place, leading to modern Homo sapiens. In the present study it is shown that these transitions must have occurred in rapid bursts, interspersed with long periods of little or no evolutionary change (stasis). This stepwise mode of encephalization is in accordance with the model of punctuated evolutionary change. A further inquiry has been made into the size of the cerebral cortex of hominids and into the number of cortical neurons based on estimates which were derived from allometric equations in extant mammals. PMID:6405974

  9. Crown-formation time of a fossil hominid premolar tooth.

    Beynon, A D; Dean, M C


    Studies using surface or internal enamel growth indicators in hominids have suggested that crown-formation times were shorter than those in modern man. The crown-formation time in a robust australopithecine premolar tooth was calculated by counting enamel cross-striations, which correspond to daily increments of formation, on a replica of the fractured internal enamel surface of cuspal enamel using scanning electron microscopy. Cervical enamel completion time was estimated using other growth indicators including striae, and using measured and calculated cross-striation repeat intervals, giving a completion time of approx. 2.4 yr. This is much shorter than reported premolar crown formation times in modern man. These findings support the concept of an abbreviated period of dental development, with implications on the duration of the growth period in early hominids. PMID:3130039

  10. Posterior dental size reduction in hominids: the Atapuerca evidence.

    Bermúdez de Castro, J M; Nicolas, M E


    In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984-1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution. PMID:7604890

  11. Age of the earliest known hominids in Java, Indonesia.

    Swisher, C C; Curtis, G H; Jacob, T; Getty, A G; Suprijo, A; Widiasmoro


    40Ar/39Ar laser-incremental heating of hornblende separated from pumice recovered at two hominid sites in Java, Indonesia, has yielded well-defined plateaus with weighted mean ages of 1.81 +/- 0.04 and 1.66 +/- 0.04 million years ago (Ma). The hominid fossils, a juvenile calvaria of Pithecanthropus and a partial face and cranial fragments of Meganthropus, commonly considered part of the Asian Homo erectus hypodigm, are at least 0.6 million years older than fossils referred to as Homo erectus (OH-9) from Olduvai Gorge, Tanzania, and comparable in age with the oldest Koobi Fora Homo cf. erectus (Homo ergaster) in Kenya. These ages lend further credence to the view that Homo erectus may have evolved outside of Africa. If the ancestor of Homo erectus ventured out of Africa before 1.8 Ma, the dispersal would have predated the advent of the Acheulean culture at 1.4 Ma, possibly explaining the absence of these characteristic stone cleavers and hand axes in East Asia. PMID:8108729

  12. Brief communication: Gladysvale: first early hominid site discovered in South Africa since 1948.

    Berger, L R; Keyser, A W; Tobias, P V


    We report here the discovery of fossil hominid teeth at Gladysvale, near Johannesburg in the southern Transvaal. This find makes the site the seventh in South Africa to yield australopithecine remains and the first new early hominid-bearing locality to be found in this region since 1948. Apart from the hominid specimens, our excavations at Gladysvale have added appreciably to the abundant Plio-Pleistocene fauna previously recorded from the cave deposit. The fauna indicates that savanna conditions prevailed during deposition of at least part of the fill. Preliminary faunal dating gives an age of deposition of between c1.7 and c2.5 mya. PMID:8238287

  13. Endocranial capacity in an early hominid cranium from Sterkfontein, South Africa.

    Conroy, G C; Weber, G W; Seidler, H; Tobias, P V; Kane, A; Brunsden, B


    Two- and three-dimensional computer imaging shows that endocranial capacity in an approximately 2.8- to 2.6-million-year-old early hominid cranium (Stw 505) from Sterkfontein, South Africa, tentatively assigned to Australopithecus africanus, is approximately 515 cubic centimeters. Although this is the largest endocranial capacity recorded for this species, it is still markedly less than anecdotal reports of endocranial capacity exceeding 600 cubic centimeters. No australopithecine has an endocranial capacity approaching, let alone exceeding, 600 cubic centimeters. Some currently accepted estimates of early hominid endocranial capacity may be inflated, suggesting that the tempo and mode of early hominid brain evolution may need reevaluation. PMID:9624045

  14. Paleomagnetic dates of hominid remains from Yuanmou, China, and other Asian sites.

    Hyodo, Masayuki; Nakaya, Hideo; Urabe, Atsushi; Saegusa, Haruo; Shunrong, Xue; Jiyun, Yin; Xuepin, Ji


    Two hominid upper central incisors found in the Yuanmou Basin in southwest China in 1965 have affinities with Homo erectus fossils from Zhoukoudian, but exhibit primitive features. The Yuanmou hominid remains are alleged to be coeval with or older than African specimens dated at about 1.8 m.y.a. Recent age refinements of geomagnetic short reversal events and excursions permit assigning the Yuanmou hominid-bearing bed to the early Brunhes chron (about 0.7 m.y.a.). Magnetochronological assessments confirm that the Lantian calotte which has been dated to about 1.2 m.y.a., is the oldest reliable evidence for the emergence of Homo in eastern Asia as well as China, and that hominid fossils from Sangiran and Mojokerto, Java, do not exceed 1.1 Ma in age. These results refute the view that the genus Homo migrated into eastern Asia in the late Pliocene or the earliest Pleistocene. PMID:12098208

  15. Stratigraphy, artefact industries and hominid associations for Sterkfontein, member 5.

    Kuman, K; Clarke, R J


    A revised stratigraphy for the early hominid site of Sterkfontein (Gauteng Province, South Africa) reveals a complex distribution of infills in the main excavation area between 2.8 and 1.4 m.y.a, as well as deposits dating to the mid to late Pleistocene. New research now shows that the Member 4 australopithecine breccia (2.8-2.6 Ma) extends further west than was previously thought, while a late phase of Member 4 is recognized in a southern area. The artefact-bearing breccias were defined sedimentologically as Member 5, but one supposed part of these younger breccias, the StW 53 infill, lacks in situ stone tools, although it does appear to post-date 2.6 Ma when artefacts first appear in the archaeological record. The StW 53 hominid, previously referred to Homo habilis, is here argued to be Australopithecus. The first artefact-bearing breccia of Member 5 is the Oldowan Infill, estimated at 2-1.7 Ma. It occupies a restricted distribution in Member 5 east and contains an expedient, flake-based tool industry associated with a few fossils of Paranthropos robustus. An enlarged cave opening subsequently admitted one or more Early Acheulean infills associated in Member 5 west with Homo ergaster. The artefacts attest to a larger site accumulation between ca. 1.7 and 1.4 Ma, with more intensive use of quartzite over quartz and a subtle but important shift to large flakes and heavier-duty tools. The available information on palaeoenvironments is summarized, showing an overall change from tropical to sub-tropical gallery forest, forest fringe and woodland conditions in Member 4 to more open woodland and grassland habitats in the later units, but with suggestions of a wet localized topography in the Paranthropus -bearing Oldowan Infill. PMID:10835264

  16. Basicranial architecture and relative brain size of Sts 5 (Australopithecus africanus) and other Plio-Pleistocene hominids

    Spoor, F.


    The cranial base has long been recognised as a complex morphological region where major structural changes have occurred during hominid evolution. Here the relationship between relative brain size and basicranial shape in modern humans, fossil hominids, Sts 5 in particular, and other primates is investigated. The results reveal that basicranial shape is well correlated with relative brain size among non-hominid primates, supporting the notion that brain size is a prime factor underlying bosic...

  17. A critique of the chronometric evidence for hominid fossils : I. Africa and the Near East 500–50 ka.

    Millard, A.R.


    The chronometric dating evidence for all hominid fossils from Africa and the Near East that have previously been dated to 500–50 ka is critically assessed using the concept of chronometric hygiene, and these dates are revised using Bayesian statistical analyses where possible. Sixteen relevant hominid sites lacking chronometric evidence are briefly discussed. Chronometric evidence from 37 sites is assessed in detail. The dates for many hominid fossils are poorly constrained, with a number dat...

  18. Interproximal grooving in the Atapuerca-SH hominid dentitions.

    Bermúdez de Castro, J M; Arsuaga, J L; Pérez, P J


    The dental sample recovered from the Sima de los Huesos (SH) Middle Pleistocene cave site of the Sierra de Atapuerca (Spain) includes 296 specimens. Interproximal wear grooves have been observed in 20 maxillary and mandibular posterior teeth belonging to at least five of the 32 individuals identified so far in the SH hypodigm. Interproximal grooving affected only the adults, and at an age between 25 and 40 years. The appearance, morphology, and location pattern of the SH wear grooves are similar to those reported in other fossil hominids and in more recent human populations. Two alternative proposals, the toothpicking and the fiber or sinew processing hypotheses, compete for explaining the formation of this anomalous wear. The characteristics observed in the wear grooves of the SH teeth are compatible only with the habitual probing of interdental spaces by means of hard and inflexible objects. Dietary grit may also have contributed to the abrasion of the root walls during the motion of the dental probes. PMID:9098505

  19. Increased cranial capacity in hominid evolution and preeclampsia.

    Chaline, Jean


    One of the major trends in primate evolution generally and hominid evolution in particular, is cranio-facial contraction accompanied by an increase in cranial capacity. Landmark-based morphometric methods are applied to adult skulls of great apes (Gorilla, Pan), australopithecines (Australopithecus and Paranthropus), and humans (Homo eragster, erectus, neanderthalensis, and sapiens). Morphological changes quantified by vector fields (Procrustes methods) indicate that these skull plans are characterized by distinctive degrees of cranio-facial contraction. These suggest the existence of three discrete skull organization plans: "great ape", "australopithecine" and "Homo". This paper focuses on the "Homo" skull bauplan and discusses the possible relationships between greatly increased cranial capacity and preeclampsia. The earliest species of the human lineage exhibit less cranio-facial contraction and smaller cranial capacity than Homo neanderthalensis and modern Homo sapiens. Neandertalization introduces a posterior elongation of the skull and leads to a large increase in cranial capacity in the last Neandertals, with values as large as in present-day H. sapiens. Consequently, a new biological hypothesis is proposed to account for the unexplained disappearance of H. neanderthalensis some 30000 years ago related to the possible appearance of preeclampsia as a factor affecting the survival of the species. PMID:12896818

  20. Gluteus maximus muscle function and the origin of hominid bipedality.

    Marzke, M W; Longhill, J M; Rasmussen, S A


    Bipedality not only frees the hands for tool use but also enhances tool use by allowing use of the trunk for leverage in applying force and thus imparting greater final velocity to tools. Since the weight and acceleration of the trunk and forelimbs on the hindlimbs must be counteracted by muscles such as m. gluteus maximus that control pelvic and trunk movements, it is suggested that the large size of the cranial portion of the human gluteus maximus muscle and its unique attachment to the dorsal ilium (which is apparent in the Makapan australopithecine ilium) may have contributed to the effectiveness with which trunk movement was exploited in early hominid foraging activities. To test this hypothesis, the cranial portions of both right and left muscles were investigated in six human subjects with electromyography during throwing, clubbing, digging, and lifting. The muscles were found to be significantly recruited when the trunk is used in throwing and clubbing, initiating rotation of the pelvis and braking it as trunk rotation ceases and the forelimb accelerates. They stabilize the pelvis during digging and exhibit marked and prolonged activity when the trunk is maintained in partial flexion during lifting of heavy objects. PMID:3223519

  1. Cenozoic vegetation, climate changes and hominid evolution in tropical Africa

    Bonnefille, Raymonde


    This paper reviews information on past vegetation of tropical Africa during the Cenozoic, focused upon the last 10 Ma, a time spanning hominid record in Central and East Africa. Summary of palaeobotanical data collected at terrestrial sites are compared with new results on the long term evolution of the continental vegetation zones documented from marine pollen record of two deep sea cores recovered from the Atlantic and Indian Oceans. Section 2 includes a summary of modern distribution of vegetation belts in the African continent and a synthesis of the results of both macrobotanical (fossil wood, leaves and fruits) and microbotanical (mainly pollen) studies presented according to time scale and geographical location. The main features emphasized by the palaeobotanical results are 1) seasonal vegetation and climate documented as soon as the Eocene in Tanzania 2) well diversified forests existing in northern West Ethiopia during the Oligocene 3) high temporal and spatial variabilities of forests composition during the Miocene when deciduous Legume woodland was documented in Ethiopia whereas wetter evergreen forests existed in Western Kenya 4) lack of evidence for an evergreen forest belt, continuous from Western Congo to East Africa. Section 3 presents new original pollen data recovered from a long core in the Gulf of Aden documenting large scale past vegetation changes in East Africa during the last 11 Ma. These results are discussed in comparison with a summarized long pollen sequence previously published from a marine core offshore the Niger delta. This comparison illustrates variations in geographical distribution of large vegetation zone at the continental scale, through time. In Section 4, vegetation changes registered during the last 10 Ma are discussed in relation with the results of isotopic studies and an updated presentation of hominids evolution in Africa. Several changes are shown in the marine records. An expansion of savanna/grassland is shown at 10

  2. Comparative taphonomy, taphofacies, and bonebeds of the Mio-Pliocene Purisima Formation, central California: strong physical control on marine vertebrate preservation in shallow marine settings.

    Robert W Boessenecker

    Full Text Available Taphonomic study of marine vertebrate remains has traditionally focused on single skeletons, lagerstätten, or bonebed genesis with few attempts to document environmental gradients in preservation. As such, establishment of a concrete taphonomic model for shallow marine vertebrate assemblages is lacking. The Neogene Purisima Formation of Northern California, a richly fossiliferous unit recording nearshore to offshore depositional settings, offers a unique opportunity to examine preservational trends across these settings.Lithofacies analysis was conducted to place vertebrate fossils within a hydrodynamic and depositional environmental context. Taphonomic data including abrasion, fragmentation, phosphatization, articulation, polish, and biogenic bone modification were recorded for over 1000 vertebrate fossils of sharks, bony fish, birds, pinnipeds, odontocetes, mysticetes, sirenians, and land mammals. These data were used to compare both preservation of multiple taxa within a single lithofacies and preservation of individual taxa across lithofacies to document environmental gradients in preservation. Differential preservation between taxa indicates strong preservational bias within the Purisima Formation. Varying levels of abrasion, fragmentation, phosphatization, and articulation are strongly correlative with physical processes of sediment transport and sedimentation rate. Preservational characteristics were used to delineate four taphofacies corresponding to inner, middle, and outer shelf settings, and bonebeds. Application of sequence stratigraphic methods shows that bonebeds mark major stratigraphic discontinuities, while packages of rock between discontinuities consistently exhibit onshore-offshore changes in taphofacies.Changes in vertebrate preservation and bonebed character between lithofacies closely correspond to onshore-offshore changes in depositional setting, indicating that the dominant control of preservation is exerted by physical processes. The strong physical control on marine vertebrate preservation and preservational bias within the Purisima Formation has implications for paleoecologic and paleobiologic studies of marine vertebrates. Evidence of preservational bias among marine vertebrates suggests that careful consideration of taphonomic overprint must be undertaken before meaningful paleoecologic interpretations of shallow marine vertebrates is attempted.

  3. Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi, South China

    WANG Wei; Richard Potts; HOU Yamei; CHEN Yunfa; WU Huaying; YUAN Baoyin; HUANG Weiwen


    Two hominid teeth recovered in Mohui cave are morphologically distinguished from Australopithecus in Africa, but close to Homo erectus in China. These teeth are therefore provisionally assigned to Homo erectus. The associated mammalian fauna include Gigantopithecus blacki, Nestoritherium sp., Sus xiaozhu, Sus peii and Ailuropoda microta, which are typical early Pleistocene taxa in South China. The general characteristics of the Mohui faunal assemblage are similar to the Longgupo site, which is dated to 2 Ma, implying a contemporaneity for the two sites. To date, compared with the discoveries in Africa, far fewer early Pleistocene hominid fossils have been recovered in Asia, and there are intensive controversies concerning their stratigraphic provenience and typological and temporal positions. The hominid fossils from Mohui cave, with their reliable biostratigraphic positions and distinct typological features, provide important evidence regarding the issue of early human origins and evolution.

  4. Earliest Pleistocene hominid cranial remains from Dmanisi, Republic of Georgia: taxonomy, geological setting, and age.

    Gabunia, L; Vekua, A; Lordkipanidze, D; Swisher, C C; Ferring, R; Justus, A; Nioradze, M; Tvalchrelidze, M; Antón, S C; Bosinski, G; Jöris, O; Lumley, M A; Majsuradze, G; Mouskhelishvili, A


    Archaeological excavations at the site of Dmanisi in the Republic of Georgia have uncovered two partial early Pleistocene hominid crania. The new fossils consist of a relatively complete cranium and a second relatively complete calvaria from the same site and stratigraphic unit that yielded a hominid mandible in 1991. In contrast with the uncertain taxonomic affinity of the mandible, the new fossils are comparable in size and morphology with Homo ergaster from Koobi Fora, Kenya. Paleontological, archaeological, geochronological, and paleomagnetic data from Dmanisi all indicate an earliest Pleistocene age of about 1.7 million years ago, supporting correlation of the new specimens with the Koobi Fora fossils. The Dmanisi fossils, in contrast with Pleistocene hominids from Western Europe and Eastern Asia, show clear African affinity and may represent the species that first migrated out of Africa. PMID:10807567

  5. Comparative anatomy of the middle ear ossicles of extant hominids--Introducing a geometric morphometric protocol.

    Stoessel, Alexander; Gunz, Philipp; David, Romain; Spoor, Fred


    The presence of three interconnected auditory ossicles in the middle ear is a defining characteristic of mammals, and aspects of ossicle morphology are related to hearing sensitivity. However, analysis and comparison of ossicles are complicated by their minute size and complex three-dimensional shapes. Here we introduce a geometric morphometric measurement protocol for 3D shape analysis based on landmarks and semilandmarks obtained from μCT images and apply it to ossicles of extant hominids (great apes and humans). We show that the protocol is reliable and reproducible over a range of voxel resolutions, and captures even subtle shape differences. Using this approach it is possible to distinguish the hominid taxa by mean shapes of their malleus and incus (p morphometric studies analyzing ossicles of extinct hominids, with a bearing on taxonomy, phylogeny and auditory function. PMID:26852810

  6. Locomotor energetics and leg length in hominid bipedality.

    Kramer, P A; Eck, G G


    Because bipedality is the quintessential characteristic of Hominidae, researchers have compared ancient forms of bipedality with modern human gait since the first clear evidence of bipedal australopithecines was unearthed over 70 years ago. Several researchers have suggested that the australopithecine form of bipedality was transitional between the quadrupedality of the African apes and modern human bipedality and, consequently, inefficient. Other researchers have maintained that australopithecine bipedality was identical to that of Homo. But is it reasonable to require that all forms of hominid bipedality must be the same in order to be optimized? Most attempts to evaluate the locomotor effectiveness of the australopithecines have, unfortunately, assumed that the locomotor anatomy of modern humans is the exemplar of consummate bipedality. Modern human anatomy is, however, the product of selective pressures present in the particular milieu in which Homo arose and it is not necessarily the only, or even the most efficient, bipedal solution possible. In this report, we investigate the locomotion of Australopithecus afarensis, as represented by AL 288-1, using standard mechanical analyses. The osteological anatomy of AL 288-1 and movement profiles derived from modern humans are applied to a dynamic model of a biped, which predicts the mechanical power required by AL 288-1 to walk at various velocities. This same procedure is used with the anatomy of a composite modern woman and a comparison made. We find that AL 288-1 expends less energy than the composite woman when locomoting at walking speeds. This energetic advantage comes, however, at a price: the preferred transition speed (from a walk to a run) of AL 288-1 was lower than that of the composite woman. Consequently, the maximum daily range of AL 288-1 may well have been substantially smaller than that of modern people. The locomotor anatomy of A. afarensis may have been optimized for a particular ecological niche

  7. Dating by fission tracks in archaeology. 3. Tephrochronology and Hominid dating

    Tephras (or volcanic ashes) are excellent stratigraphic tracers. Its utilization in this domain, or tephrochronology, is shortly presented. The main archaeological utilization of the tephrochronology is related with the dating of fossil hominids, there where exist the volcano-fossil sedimentar series, at Ceylon or at East-African Rift. (L.C.)

  8. New evidence for hominid presence in the Lower Pleistocene of the Southern Levant.

    Belmaker, Miriam; Tchernov, Eitan; Condemi, Silvana; Bar-Yosef, Ofer


    The site of 'Ubeidiya is located in the Jordan Valley, Israel and has been biochronologically dated to 1.5 m.y.a. It exhibits large lithic and faunal assemblages. Previous published hominid material includes a molar (UB 1701) and I(2) (UB 1700). A recent review of the faunal material from previous excavations has revealed a highly worn hominid right lateral lower incisor (UB 335). The tooth was found in situ in the Lower Pleistocene deposits of stratum I-26a, which is comprised of sand and conglomerates of flint, limestone and basalt indicative of a pebbled lakeshore environment. Taphonomic analysis of the macromammal assemblage indicates high-energy fluvial transport. Paleoecological reconstruction suggests a large woodland fauna with a small percent of open steppe species.UB 335 did not differ significantly from the Lower Pleistocene hominid and modern populations but did differ significantly from all other fossil populations. Two-tailed Student t -test and single classification Model II ANOVA of the buccolingual diameter did not distinguish between Lower Pleistocene species: Homo habilis, H. ergaster and H. cf. erectus. Thus, UB 335 can be identified as a Lower Pleistocene hominid although it cannot be securely assigned to any particular species within that time frame. The current date of the 'Ubeidiya deposits and the location of the site within the Levantine corridor suggests a tenative identification as H. ergaster. PMID:12098209

  9. Evidence for widespread degradation of gene control regions in hominid genomes.

    Peter D Keightley


    Full Text Available Although sequences containing regulatory elements located close to protein-coding genes are often only weakly conserved during evolution, comparisons of rodent genomes have implied that these sequences are subject to some selective constraints. Evolutionary conservation is particularly apparent upstream of coding sequences and in first introns, regions that are enriched for regulatory elements. By comparing the human and chimpanzee genomes, we show here that there is almost no evidence for conservation in these regions in hominids. Furthermore, we show that gene expression is diverging more rapidly in hominids than in murids per unit of neutral sequence divergence. By combining data on polymorphism levels in human noncoding DNA and the corresponding human-chimpanzee divergence, we show that the proportion of adaptive substitutions in these regions in hominids is very low. It therefore seems likely that the lack of conservation and increased rate of gene expression divergence are caused by a reduction in the effectiveness of natural selection against deleterious mutations because of the low effective population sizes of hominids. This has resulted in the accumulation of a large number of deleterious mutations in sequences containing gene control elements and hence a widespread degradation of the genome during the evolution of humans and chimpanzees.

  10. Patterns and rates of enamel growth in the molar teeth of early hominids.

    Beynon, A D; Wood, B A

    A recent study of the surface manifestation of incremental lines associated with enamel formation suggested that the crowns of early hominid incisor teeth were formed more rapidly than those of modern humans. In the absence of comparative data, the authors were forced to assume that enamel increments in fossil teeth were similar to those in modern humans. We have used evidence from the fractured surfaces of molar teeth to deduce estimates for both long- and short-period incremental growth markers within enamel in east African 'robust' australopithecine and early Homo teeth. We conclude that in these early hominids, crown formation times in posterior teeth, particularly in the large thick enamelled molar teeth of the east African 'robust' australopithecines, were shorter than those of modern humans. This evidence, considered together with data on crown and root formation times in modern apes, suggests that the posterior teeth in these hominids both formed and erupted more rapidly than those of modern man. These results have implications for attempts to assess dental and skeletal maturity in hominids. PMID:3104794

  11. Lapa vermelha IV Hominid 1: morphological affinities of the earliest known American

    Neves Walter A.


    Full Text Available Several studies concerning the extra-continental morphological affinities of Paleo-Indian skeletons, carried out independently in South and North America, have indicated that the Americas were first occupied by non-Mongoloids that made their way to the New World through the Bering Strait in ancient times. The first South Americans show a clear resemblance to modern South Pacific and African populations, while the first North Americans seem to be at an unresolved morphological position between modern South Pacific and Europeans. In none of these analyses the first Americans show any resemblance to either northeast Asians or modern native Americans. So far, these studies have included affirmed and putative early skeletons thought to date between 8,000 and 10,000 years B.P. In this work the extra-continental morphological affinities of a Paleo-Indian skeleton well dated between 11,000 and 11,500 years B.P. (Lapa Vermelha IV Hominid 1, or "Luzia" is investigated, using as comparative samples Howells' (1989 world-wide modern series and Habgood's (1985 Old World Late Pleistocene fossil hominids. The comparison between Lapa Vermelha IV Hominid 1 and Howells' series was based on canonical variate analysis, including 45 size-corrected craniometric variables, while the comparison with fossil hominids was based on principal component analysis, including 16 size-corrected variables. In the first case, Lapa Vermelha IV Hominid 1 exhibited an undisputed morphological affinity firstly with Africans and secondly with South Pacific populations. In the second comparison, the earliest known American skeleton had its closest similarities with early Australians, Zhoukoudian Upper Cave 103, and Taforalt 18. The results obtained clearly confirm the idea that the Americas were first colonized by a generalized Homo sapiens population which inhabited East Asia in the Late Pleistocene, before the definition of the classic Mongoloid morphology.

  12. New Isotopic and Sedimentological Measurements of the Thabaseek Deposits (South Africa) and the Dating of the Taung Hominid

    Tobias, Phillip V.; Vogel, John C.; Oschadleus, H. Dieter; Partridge, Timothy C.; McKee, Jeffrey K.


    Earlier attempts to date the Taung hominid type specimen of Australopithecus africanus Dart yielded conflicting results. Recent faunal studies pointed to an age of 2.3 myr. Radioisotopic results suggested 1.0 myr. New uranium studies reveal that the Thabaseek (the oldest Taung tufa) was not a closed system and that younger uranium entered the tufa after initial deposition, producing an apparent isotopic age younger than the age of deposition. The Thabaseek isotopic dates provide only a terminus ad quem and this technique is therefore not applicable to the older Taung tufas. Delson's dating (2.3 myr) of cercopithecoids from Hrdlicka's pinnacle ca. 50 m from the hominid site provides the best available approximation to the age of the hominid. In our new Taung excavation, stratigraphic analysis indicates that the hominid may somewhat predate most identified fauna. Sedimentologically the hominid matrix proves to be of fluvial deposition, and hence closely resembles one Hrdlicka deposit, both samples differing appreciably from all other Taung samples which bespeak eolian deposition. Thus, the conditions under which the hominid-bearing stratum was deposited were virtually identical to those pertaining to one of the Hrdlicka deposits. The newest results show that Taung was not the youngest South African australopithecine site and eliminate the discrepancy between the relative ages of the Taung A. africanus africanus and the Sterkfontein A. africanus transvaalensis.

  13. Direct dating of hominids using ESR and U-series dating

    Gruen, R. [Australian National University, Canberra, ACT (Australia). Research School of Earth Science


    Full text: Dating studies on palaeoanthropological sites is usually carried out on material associated with the human remains, such as the sediment, charcoal or other fauna rather than the human specimen itself. The reason lies in the fact that most dating techniques are destructive and because the hominid remains are too rare to be sacrificed for dating. This indirect dating approach is in many cases not satisfactory, because:(i) the human remains are often buried into the sediments and the association with other materials is uncertain (e.g. Skhul, Qafzeh, etc.);(ii) faunal remains or minerals from the sediment are re-worked from older deposits (see e.g. present discussion of the age of the Homo erectus remains in Indonesia);(iii) the hominid specimen was discovered at a time when no careful excavations were carried out and it is impossible to correlate the specimen with other datable material (nearly 90% of all palaeoanthropological specimen). For example, the hominid burial site of Qafzeh in Israel has been dated by several independent dating laboratories with a multitude of methods. However, the data are still not accepted by some because the dating has not been carried out on the hominid specimen. Until recently, hominid fossils could only be dated by radiocarbon. This method reaches back to about 40,000 years. As a consequence, all the older fossils could not be analysed and many important questions in our understanding of human evolution could not be addressed. Human remains are scarce and extremely valuable, therefore any sort of destruction has to be kept to an absolute minimum. This is of particular importance in Australia where any human fossils are sacred. Thus, for the analysis of hominid material it was necessary to develop a more or less non-destructive techniques. This has been accomplished in recent years by the application of ESR dating of tooth enamel and a combination of gamma spectrometric and TIMS U-series dating of bones. The examples of

  14. Dental size variation in the Atapuerca-SH Middle Pleistocene hominids.

    Bermúdez de Castro, J M; Sarmiento, S; Cunha, E; Rosas, A; Bastir, M


    The Middle Pleistocene Atapuerca-Sima de los Huesos (SH) site in Spain has yielded the largest sample of fossil hominids so far found from a single site and belonging to the same biological population. The SH dental sample includes a total of 452 permanent and deciduous teeth, representing a minimum of 27 individuals. We present a study of the dental size variation in these hominids, based on the analysis of the mandibular permanent dentition: lateral incisors, n=29; canines, n=27; third premolars, n=30; fourth premolars, n=34; first molars, n=38; second molars, n=38. We have obtained the buccolingual diameter and the crown area (measured on occlusal photographs) of these teeth, and used the bootstrap method to assess the amount of variation in the SH sample compared with the variation of a modern human sample from the Museu Antropologico of the Universidade of Coimbra (Portugal). The SH hominids have, in general terms, a dental size variation higher than that of the modern human sample. The analysis is especially conclusive for the canines. Furthermore, we have estimated the degree of sexual dimorphism of the SH sample by obtaining male and female dental subsamples by means of sexing the large sample of SH mandibular specimens. We obtained the index of sexual dimorphism (ISD=male mean/female mean) and the values were compared with those obtained from the sexed modern human sample from Coimbra, and with data found in the literature concerning several recent human populations. In all tooth classes the ISD of the SH hominids was higher than that of modern humans, but the differences were generally modest, except for the canines, thus suggesting that canine size sexual dimorphism in Homo heidelbergensis was probably greater than that of modern humans. Since the approach of sexing fossil specimens has some obvious limitations, these results should be assessed with caution. Additional data from SH and other European Middle Pleistocene sites would be necessary to test

  15. A cranium for the earliest Europeans: Phylogenetic position of the hominid from Ceprano, Italy

    Manzi, G; F. Mallegni; Ascenzi, A.


    The human fossil evidence unequivocally pertaining to the first inhabitants of Europe at present includes the sample from Atapuerca-TD6 (Spain) and the incomplete adult calvaria discovered near Ceprano, in Southern Latium (Italy). On the basis of regional correlations and a series of absolute dates, the age of the Ceprano hominid is estimated to range between 800 and 900 kilo-annum (ka). In addition, the association with archaic (Mode 1) Paleolithic findings from the s...

  16. Revisions of K/Ar ages for the Hadar hominid site, Ethiopia

    Conventional K/Ar age measurements are reported for two volcanic units from the hominid-bearing Hadar Formation. These ages represent revision of previously published ages for the BKT-2 tephra and the Kadada Moumou basalt. BKT-2 is revised from 2.65 to 2.9 Myr BP and the Kadada Moumou basalt is revised from 3.0 to 3.6 Myr BP. (author)

  17. Preliminary study on the living environment of hominids at the Donggutuo site,Nihewan Basin

    PEI ShuWen; LI XiaoLi; LIU DeCheng; MA Ning; PENG Fei


    The Donggutuo site,situated in the east margin of Nihewan basin,is one of the most important Paleolithic sites in China,characterized by the longest excavation seasons and the most abundant cultural remains recovered in the region.Based on well-constructed sporopollen,sediment grain size analysis,magnetic susceptibility,and iron oxide analysis of the 2000-2001 excavated section,four stages of environmental change in the Nihewan Beds are identified by the authors.The results indicate four major stages of environment and climate change from 1) warm and humid forest grass to 2) temperate and humid forest grass to 3) temperate and dry forest grass to 4) warm and humid forest,which is suitable for hominid occupation.The changes correspond to the stages of lake transgression and regression.The environment after the lake died out away has been cold and dry boschveld.The hominid activities at the site took place in the Early Pleistocene (1.10 Ma),which corresponds to the early three environmental stages.Therefore,it can be inferred that the early hominids adapted to the relatively low lake level episodes through activities involving sporadic stone tool making,procuring of raw materials for tools,concentrating stone artifacts,and hunting and butchering.In conclusion,the results will be of great significance to research regarding the relationship between hominid occupation and environmental changes as well as the adaptive behaviors of early humans at the Donggutuo site.

  18. Africa's wild C4 plant foods and possible early hominid diets.

    Peters, Charles R; Vogel, John C


    A small minority of Africa's wild plant foods are C4. These are primarily the seeds of some of the C4 grasses, the rootstocks and stem/leaf bases of some of the C4 sedges (especially papyrus), and the leaves of some of the C4 herbaceous dicots (forbs). These wild food plants are commonly found in disturbed ground and wetlands (particularly the grasses and sedges). Multiple lines of evidence indicate that C4 grasses were present in Africa by at least the late Miocene. It is a reasonable hypothesis that the prehistory of the C4 sedges parallels that of the C4 grasses, but the C4 forbs may not have become common until the late Pleistocene. CAM plants may have a more ancient history, but offer few opportunities for an additional C4-like dietary signal. The environmental reconstructions available for the early South African hominid sites do not indicate the presence of large wetlands, and therefore probably the absence of a strong potential for a C4 plant food diet. However, carbon isotope analyses of tooth enamel from three species of early South African hominids have shown that there was a significant but not dominant contribution of C4 biomass in their diets. Since it appears unlikely that this C4 component could have come predominantly from C4 plant foods, a broad range of potential animal contributors is briefly considered, namely invertebrates, reptiles, birds, and small mammals. It is concluded that the similar average C4 dietary intake seen in the three South African hominid species could have been acquired by differing contributions from the various sources, without the need to assume scavenging or hunting of medium to large grazing ungulates. Effectively similar dominantly dryland paleo-environments may also be part of the explanation. Theoretically, elsewhere in southern and eastern Africa, large wetlands would have offered early hominids greater opportunities for a C4 plant diet. PMID:15737391

  19. Pattern of dental development in Hominid XVIII from the Middle Pleistocene Atapuerca-Sima de los Huesos site (Spain).

    Bermudez De Castro, J M; Rosas, A


    . We describe the pattern of dental development of Hominid XVIII from the Middle Pleistocene Sima de los Huesos (SH) site of the Sierra de Atapuerca (Burgos, Spain). As expected, this pattern is similar to that of modern humans. A delay of development of the lower and upper canines was observed. In contrast, the relative advanced development of the lower second molars and, especially, the upper and lower third molars is noteworthy. This latter feature seems to be common in Pleistocene hominids, and suggests that the pattern of dental development evolved in the genus Homo during the Pleistocene. In European Middle Pleistocene hominids, this pattern probably was facilitated by the extra space available in the mandible and maxilla for developing teeth. PMID:11275961

  20. Human taxonomic diversity in the pleistocene: does Homo erectus represent multiple hominid species?

    Kramer, A


    Recently, nomina such as "Homo heidelbergensis" and "H. ergaster" have been resurrected to refer to fossil hominids that are perceived to be specifically distinct from Homo sapiens and Homo erectus. This results in a later human fossil record that is nearly as speciose as that documenting the earlier history of the family Hominidae. However, it is agreed that there remains only one extant hominid species: H. sapiens. Has human taxonomic diversity been significantly pruned over the last few hundred millennia, or have the number of taxa been seriously overestimated? To answer this question, the following null hypothesis is tested: polytypism was established relatively early and the species H. erectus can accommodate all spatio-temporal variation from ca. 1.7 to 0.5 Ma. A disproof of this hypothesis would suggest that modern human polytypism is a very recent phenomenon and that speciation throughout the course of human evolution was the norm and not the exception. Cranial variation in a taxonomically mixed sample of fossil hominids, and in a modern human sample, is analyzed with regard to the variation present in the fossils attributed to H. erectus. The data are examined using both univariate (coefficient of variation) and multivariate (determinant) analyses. Employing randomization methodology to offset the small size and non-normal distribution of the fossil samples, the CV and determinant results reveal a pattern and degree of variation in H. erectus that most closely approximates that of the single species H. sapiens. It is therefore concluded that the null hypothesis cannot be rejected. PMID:8317558

  1. Huanglong Cave, a new late Pleistocene hominid site in Hubei Province, China

    WU Xianzhu; LIU Wu; GAO Xing; YIN Gongming


    For the past 20 years the modern human origins debate has received a significant amount of attention in paleoanthropological research. Primarily supported by the evidence of earlier dates of anatomically modern human fossils and genetic studies, the "Out of Africa" hypothesis is based on the belief that the ancestor of all modern humans, including modern Chinese, came from Africa. The opposite hypothesis "Mutiregional evolution" proposes that continuous evolution occurred on a regional scale, for which human paleontology offers strong support. However, due to the paucity of hominid fossils in China between 100 and 50 ka, support to the latter hypothesis is currently weak. This is a report here of five human fossil teeth, and associated stone tools and mammal fossils from a newly discovered cave site, Huanglong Cave, located in Yunxi County,Hubei Province, China. Preliminary studies indicate:(1) the morphological features of the human fossils resemble those of late Pleistocene human fossils from China; (2) the stone tools display patterns of both the southern and northern Paleolithic cultures of China; (3) the mammal fossils represent the "Ailuropoda-Stegodon" faunal unit which lived in southern China throughout the Pleistocene. ESR and U-series dating on animal teeth and a stalagmite derived from the same layer as the human teeth indicate two possible ages: 103±1.6 ka and 44±12.5 ka. In addition to other evidence presented here, it is believed that hominid occupation of the cave was likely around 100 ka. If this age is further substantiated, Huanglong Cave will be the first late Pleistocene hominid fossil site in China where anatomically modern humans lived about 100 ka. The human fossils and other related materials from Huanglong Cave will provide important information for research on the origin of modern Chinese.

  2. Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo.

    Lague, Michael R; Collard, Nicole J; Richmond, Brian G; Wood, Bernard A


    Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo (including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group 'distinctness values') was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of 'distinctness values' was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of 'distinctness values' test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the

  3. Heterochronic processes in human evolution: an ontogenetic analysis of the hominid pelvis.

    Berge, C


    Changes in pelvic shape in human ontogeny and hominid phylogeny suggest that the heterochronic processes involved differ greatly from the neotenic process traditionally described in the evolution of the skull. The morphology of 150 juvenile and adult pelves of African apes, 60 juvenile and adult pelves of modern humans, two adult pelves and a juvenile hip bone of australopithecines (Sts 14, AL 288, MLD 7) was studied. Multivariate results, ontogenetic allometries, and growth curves confirm that the pelvic growth pattern in humans differs markedly from those of the African apes. The results permit the following conclusions. First, the appearance of a new feature (acetabulo-cristal buttress and cristal tubercle) at the time of human birth allows the addition of traits, such as the attainment of a proportionally narrower pelvis, with more sagittally positioned iliac blades. Pelvic proportions and orientation change progressively in early childhood as bipedalism is practiced. Other changes in pelvic proportions occur later with the adolescent growth spurt. Second, comparison of juvenile and adult australopithecines to modern humans indicates that 1) some pelvic traits of adult Australopithecus resemble those of neonate Homo; 2) the pelvic growth of Australopithecus was probably closer to that of apes, than to that of humans; and 3) prolonged growth in length of hindlimb and pelvis after sexual maturity seems to be a unique feature of Homo. The position of the acetabulo-cristal buttress and of the cristal tubercle on the ilium are similar in adult Australopithecus and neonate Homo suggesting that this feature may have been displaced later during hominid evolution. Progressive displacement of the acetabulo-cristal buttress on the ilium occurs both during hominid evolution (from Australopithecus to Homo sapiens) and human growth (from neonate to adult). This suggests peramorphic evolution of the pelvic morphology of hominids combining three processes of recapitulation

  4. A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania

    Brochu, Christopher A.; Njau, Jackson; Blumenschine, Robert J.; Densmore, Llewellyn D.


    Background The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular “horns” over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus. Methodology/Principal Findings The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma), in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus. Conclusions/Significance The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus. PMID:20195356

  5. Subnasal morphological variation in fossil hominids: a reassessment based on new observations and recent developmental findings.

    McCollum, M A


    Quantitative and qualitative assessments of subnasal morphology in fossil hominids yield distinct patterns which have been used both to sort robust from nonrobust australopithecine taxa and to distinguish individual species. Recently, new developmental models have been applied to hominoid subnasal morphological variation. These studies require that certain features of the fossil hominid subnasal region, in particular the topography of the nasal cavity entrance and details of vomeral morphology, be reevaluated. This study does so for the robust and nonrobust australopithecines, early Homo (H. habilis/H. rudolfensis), and African H. erectus. Results reaffirm an overall similarity of the nonrobust Australopithecus subnasal morphological pattern with that of the chimpanzee. They further indicate that a vomeral insertion above the nasal surface of the premaxilla should be added to the list of traits characteristic of the robust australopithecine subnasal morphological pattern. Finally, reassessment of subnasal morphology in the early Homo and H. erectus samples from Africa suggest that these two taxa share a similar subnasal morphological pattern. This pattern consists of a smooth nasal cavity entrance, a horizontal nasal sill whose anterior edge is demarcated by a strong nasal crest, and a well-developed horizontal spine at the posterior edge of the nasal sill. Although none of the African fossil Homo specimens preserve a vomer, indirect evidence suggests that it would have inserted above the nasal sill. PMID:10813707

  6. A new horned crocodile from the Plio-Pleistocene hominid sites at Olduvai Gorge, Tanzania.

    Christopher A Brochu

    Full Text Available BACKGROUND: The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular "horns" over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus. METHODOLOGY/PRINCIPAL FINDINGS: The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma, in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus. CONCLUSIONS/SIGNIFICANCE: The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus.

  7. Hominids and palaeoenvironments in the Moravian Karst during Marine Isotope Stage 3: New excavations in Pod Hradem Cave, Czech Republic

    Nejman, L.; Wright, D.; Lisá, Lenka; Doláková, N.; Horáček, I.; Novák, J.; Wood, R.; Pacher, M.; Sázelová, S.; Holub, M.; Přichystal, A.; Nývltová Fišáková, Miriam; Bajer, A.


    Roč. 87, č. 337 (2013). ISSN 0003-598X Institutional support: RVO:67985831 ; RVO:68081758 Keywords : Hominids * Moravian Karst * Pod Hradem * cave Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 1.594, year: 2013

  8. A critique of the chronometric evidence for hominid fossils: I. Africa and the Near East 500-50 ka.

    Millard, Andrew R


    The chronometric dating evidence for all hominid fossils from Africa and the Near East that have previously been dated to 500-50 ka is critically assessed using the concept of chronometric hygiene, and these dates are revised using Bayesian statistical analyses where possible. Sixteen relevant hominid sites lacking chronometric evidence are briefly discussed. Chronometric evidence from 37 sites is assessed in detail. The dates for many hominid fossils are poorly constrained, with a number dated by comparisons of faunal assemblages-a method that does not have good chronological resolution for much of the last million years. For sites with stratigraphic sequences of dates, it is generally possible to refine the dating, but in some cases, the revised chronology is less precise than previous chronologies. Fossils over 200 ka in age tend to be poorly dated, but for the last 200 kyr, dating is better due to the availability of electron-spin-resonance and thermoluminescence dating. Consideration of the chronologies favored by the proponents of the out-of-Africa and multiregional hypotheses of human evolution shows their selectivity. The chronological assessment of the fossils here is compatible with either hypothesis. If evolutionary schemes that do not rely on the morphology of the hominid fossils to decide the sequence of fossils are to be built, then further dating is required, alongside full publication of existing dates. PMID:18201747

  9. Pedo-sedimentary dynamics of the Sangiran dome hominid bearing layers (Early to Middle Pleistocene, central Java, Indonesia) : a palaeopedological approach for reconstructing 'Pithecanthropus' (Javanese Homo erectus) palaeoenvironment

    Brasseur, B.; Sémah, F.; Sémah, Anne-Marie; Djubiantono, T.


    Fossil soils and pedosediments displayed in Quaternary fossil-bearing formations are an important proxy to describe the evolution of climates and environments. Through a study of the palaeosols in the Sangiran dome, a rich hominid-bearing site of central Java (Indonesia), we characterized their record of terrestrialization through regional volcano-tectonic activity and describe palaeoenvironments colonized by hominids. The thick sedimentary formations of the Sangiran dome are known to reflect...

  10. Radiometric dating of quaternary deposits and the hominid mandible of lake banyolas, Spain

    Julia, R.; Bischoff, J.L.


    We report results of U-series analyses of the travertine matrix surrounding the Banyolas mandible that indicate an age of 45??4 ka bp. The mandible, an archaic hominid fossil generally deemed of mid-Pleistocene age, was recovered from a travertine matrix in 1887. Similar analyses on 21 travertine samples from quarries near the discovery site yield coherent U-series dates in correct stratigraphic order, ranging from 44 ka bp to 117 ka bp. Isotopic composition of these samples and the mandible matrix show no evidence of open system behaviour. Coherent isotopic results from adjacent quarries support the validity of the date on the mandible travertine, and we conclude the mandible is much younger than previously believed. ?? 1991.

  11. Lower Pleistocene hominids and artifacts from Atapuerca-TD6 (Spain)

    Carbonell, E; Bermúdez de Castro, J M; Arsuaga, J L; Díez, J C; Rosas, A; Cuenca-Bescós, G; Sala, R; Mosquera, M; Rodríguez, X P


    Human remains dating to more than 780,000 years ago are associated with a rich faunal and lithic assemblage in the Pleistocene cave site of Gran Dolina (TD), Sierra de Atapuerca, Burgos, Spain. The micromammal species represent the late Biharian (Mimomys savini zone), and the lithic objects represent pre-Acheulean technology (Mode 1) and comes from the TD6 level below the Matuyama-Brunhes boundary. The Gran Dolina hominid fossils cannot be comfortably accommodated in any of the defined Homo species. They could be considered a primitive form of Homo heidelbergensis, but a new species might be named in the future if the sample is enlarged. The new human fossil evidence demonstrates that Western Europe was settled at least since the late early Pleistocene. PMID:7638598

  12. Hominid cranium from Omo: Description and taxonomy of Omo-323-1976-896.

    Alemseged, Zeresenay; Coppens, Yves; Geraads, Denis


    Omo-323-1976-896, a partial hominid cranium dated to ca. 2.1 from the Member G, Unit G-8 of the Shungura Formation, lower Omo Basin of Ethiopia, is described. It is suggested that the specimen is an adult male based on the well-developed and completely fused sagittal crest; heavily worn teeth; relatively large canine; and size of the articular eminence. Omo-323 consists of fragments of the frontal, both temporals, occipital, parietals, and the right maxilla, and is attributed to Australopithecus boisei, making it the oldest known cranium of this species. The specimen shares features with Australopithecus aethiopicus (KNM-WT 17000), thus supporting the existence of an evolving East African robust lineage between ca. 2.6-1.2 Ma. The morphology of Omo-323 increases our knowledge of the intraspecific variability of A.boisei. PMID:11815945

  13. Cranial vault shape in fossil hominids: Fourier descriptors in norma lateralis.

    Lestrel, P E; Ohtsuki, F; Wolfe, C A


    Two major views of human evolution have elicited considerable controversy. These are: [1] the "out of Africa" hypothesis and [2] the "multiregional" hypothesis. This paper is an attempt to try to reconcile these two scenarios using hominid cranial vault data. Elliptical Fourier functions (EFFs) were used to describe, in visual and numerical terms, the shape of the human cranial vault in norma lateralis. Using jpeg images, contours of the cranial vault of a large sample of hominid specimens were pre-processed in Photoshop CS and rotated in 2D space (positional-orientation) so that a line drawn from nasion to porion was horizontal. The cranial vault image was then digitized with 72 closely-spaced points and submitted to a specially written routine that computed EFFs normalized by scaling (size-standardization). This ensured that the representation was invariant with respect to starting point, size and orientation. Statistically significant differences were found between the H. sapiens sample and both the H. erectus and H. neanderthalensis samples. In contrast, there were no statistically significant differences between the H. erectus and H. neanderthalensis groups, leading to three conclusions: [1] the similarity in cranial vault shape between H. erectus and H. neanderthalensis suggests a single gradually evolving lineage; [2] The taxon H. heidelbergensis can be embedded into the H. erectus→H. neanderthalensis line; and [3] H. sapiens seems to be a separate evolutionary development and is considered here either as a separate species or as a possible example of an allopatric semispecies (Grant, 1977). The results here suggest that human evolution over the last 2 Ma may turn out to be neither totally multiregional or simply out of Africa but rather represents a considerably more complicated picture. PMID:20801442

  14. A new application of dental wear analyses: estimation of duration of hominid occupations in archaeological localities.

    Rivals, Florent; Schulz, Ellen; Kaiser, Thomas M


    Characterization of settlement patterns is one of the core concepts in archeological research. The duration of an occupation is usually estimated through zooarchaeology (e.g., density of remains, cementochronology) and is limited by taphonomic processes and sample size. We propose a new application of dental wear methods for estimating the relative duration of hominid settlements in Paleolithic sites. Dental microwear is known to be sensitive to seasonal changes in diet. In this new application we use microwear scratch counts to estimate the variation in the dietary signal of various ungulate species. We propose that this variation is correlated to the duration of site occupation. Each season presents a limited and different set of food resources available in the environment. If animals are sampled only during a specific season (i.e., during a short term occupation) then they would be expected to have a dental wear signal with little variation. On the other hand, a greater diversity of food is available across different seasons. Therefore, if game animals are hunted through various seasons during long occupation periods, then they would be expected to have more variable dental wear. The application of this technique to the Middle Paleolithic site of Arago Cave (France), where various types of occupations occurred, supports this hypothesis. When combined with multidisciplinary studies of archaeological localities (seasonality in particular), this new application of dental wear analysis presents valuable information about hominid settlements and behavior. We contextualize our data with results from lithic and zooarchaeological analyses from Arago. These results reveal the presence of both high and low mobility groups of Homo heidelbergensis throughout the sequence of the Arago Cave. PMID:19361836

  15. On the age of the hominid fossils at the Sima de los Huesos, Sierra de Atapuerca, Spain: paleomagnetic evidence.

    Parés, J M; Pérez-González, A; Weil, A B; Arsuaga, J L


    We report new paleomagnetic data for the Middle Pleistocene hominid-bearing strata in the Sima de los Huesos, North Spain. Sediments (brown muds with human and bear fossils and the underlying sterile clayey and sandy unit) preserve both normal and reversed magnetic components. The sterile unit has exclusively reversed magnetization, dating back to the Matuyama Chron, and thus is Lower Pleistocene in age. The overlying fossiliferous muds have a dominant normal magnetization that overprints a partially resolved reversed magnetization. These data are compatible with one of the reversal events that occurred during the Brunhes Chron. Combined with the existing U-series dates and evidence from the macro- and microfauna, these paleomagnetic results suggest an age of the hominid fossils between 325 to 205 ka, whereas the underlying sand and silts are older than 780 ka. PMID:10727965

  16. Hominid exploitation of the environment and cave bear populations. The case of Ursus spelaeus Rosenmüller-Heinroth in Amutxate cave (Aralar, Navarra-Spain).

    Torres, Trinidad; Ortiz, José E; Cobo, Rafael; de Hoz, Pedro; García-Redondo, Ana; Grün, Rainer


    Cave bears (Ursus deningeri and U. spelaeus) and hominids (Homo heidelbergensis, H. neanderthalensis, and H. sapiens) were potential competitors for environmental resources (subterranean and open air). Here, we examined the age at death of cave bear (Ursus spelaeus Rosenmüller-Heinroth) specimens from Amutxate cave in order to shed light on the effect of resource sharing between cave bears and hominids. After studying dental wear of the deciduous and permanent dentitions, the ontogenetic development of mandibles, and incremental layers of cement (annuli), we defined five age groups differentiated by marked development and size gaps. Our findings indicate that after hibernating, bears abandoned the den, thereby leaving the subterranean environment (caves) free for temporary hominid occupation-this would explain the subtle traces of hominid presence in many dens. However, a simple calculation based on age at death of subadult and adult cave bear specimens in Amutxate cave, extrapolated to the whole cave area, showed that the area surrounding this cave hosted bears for at least 9,000 years. This length of habitation, quite similar to the time-span derived from amino acid racemization and electron spin resonance, indicates that bear populations in the Amutxate cave constituted a serious constraint for hominid exploitation of the environment. PMID:16996576

  17. Size counts: evolutionary perspectives on physical activity and body size from early hominids to modern humans.

    Leonard, William R


    This paper examines the evolutionary origins of human dietary and activity patterns, and their implications for understanding modern health problems. Humans have evolved distinctive nutritional characteristics associated the high metabolic costs of our large brains. The evolution of larger hominid brain size necessitated the adoption of foraging strategies that both provided high quality foods, and required larger ranges and activity budgets. Over time, human subsistence strategies have become ever more efficient in obtaining energy with minimal time and effort. Today, populations of the industrialized world live in environments characterized by low levels of energy expenditure and abundant food supplies contributing to growing rates of obesity. Analyses of trends in dietary intake and body weight in the US over the last 50 years indicate that the dramatic rise in obesity cannot be explained solely by increased energy consumption. Rather, declines in activity are also important. Further, we find that recent recommendations on physical activity have the potential to bring daily energy expenditure levels of industrialized societies surprisingly close to those observed among subsistence-level populations. These findings highlight the importance of physical activity in promoting nutritional health and show the utility of evolutionary approaches for developing public health recommendations. PMID:21116013

  18. A cranium for the earliest Europeans: phylogenetic position of the hominid from Ceprano, Italy.

    Manzi, G; Mallegni, F; Ascenzi, A


    The human fossil evidence unequivocally pertaining to the first inhabitants of Europe at present includes the sample from Atapuerca-TD6 (Spain) and the incomplete adult calvaria discovered near Ceprano, in Southern Latium (Italy). On the basis of regional correlations and a series of absolute dates, the age of the Ceprano hominid is estimated to range between 800 and 900 kilo-annum (ka). In addition, the association with archaic (Mode 1) Paleolithic findings from the same area is suggested. After the completed reconstruction of the calvaria, we present here a new study dealing with the general and more detailed aspects of the morphology displayed by Ceprano, in comparison to fossil samples ranging between Early and Middle Pleistocene. According to our results, cranial features indicate that Ceprano represents a unique morphological bridge between the clade Homo ergaster/erectus and later Middle Pleistocene specimens commonly referred to Homo heidelbergensis (and/or to Homo rhodesiensis), particularly those belonging to the African fossil record that ultimately relates to the origin of modern humans. In conclusion, given its geographical, chronological, and phylogenetic position, an attribution to the species Homo antecessor is considered, although the sample from Atapuerca-TD6 is not directly comparable to Ceprano. Alternatively, a new species-ancestral to later European and African hominines-should be named to accommodate such a unique fossil specimen. PMID:11504953

  19. Hominid dispersal into Europe around the Matuyama/Brunhes boundary: origin and significance in human evolution

    García Sánchez, Eduardo


    Full Text Available A review of the European Lower Palaeolithic record shows three human dispersal episodes. The second one is dated between OIS25/OIS24-OIS19/OIS18. It is recorded by lithic assemblages and human remains that point to an eastern Asian origin. This paper reviews this hominid dispersal, related to the Galerian faunal event. Also we analyse the most feasible migratory routes, and the reasons of its abrupt ending. The phylogenetic relationships of these populations are also proposed, putting their context into the human evolutionary sequences of the Lower and Middle Pleistocene.

    La revisión del registro inferopaleolítico europeo permite identificar tres episodios de poblamiento. El segundo de los mismos, datado entre OIS25/OIS24-OIS19/OIS18, ofrece industrias líticas y fósiles humanos que indican un posible origen esteasiático. Se ofrece una síntesis sobre este episodio de dispersión, relacionado con el reemplazo de faunas galerienses. Se analizan las posibles vías migratorias que siguió y los motivos que pudieron ocasionar su interrupción. También se plantean las relaciones filogenéticas de estas poblaciones, insertándolas en el marco evolutivo del Pleistoceno inferior y medio.

  20. Analysis of the dental morphology of Plio-Pleistocene hominids. V. Maxillary postcanine tooth morphology.

    Wood, B A; Engleman, C A


    A total of 139 maxillary molar crowns and 79 maxillary premolar crowns, from at least 98 individual East and Southern African Plio-Pleistocene hominids, has been subjected to detailed morphometric analysis. All but 16 of the 98 specimens were assigned to taxonomic categories identified as EAFROB, EAFHOM, SAFGRA, SAFROB and EAFHER. The analysis was based on whole crowns and the component cusps. While there was variable overlap between the ranges of measured crown base area of the two Southern African taxa, there was little, or no, overlap between the two major East African taxonomic categories. Crown shape distinguished EAFHOM from the three other australopithecine taxa, especially for P3, P4 and M1. Of the non-metrical traits, the expression of Carabelli's complex and the incidence of a distal cuspule discriminate best between the categories. Analysis of the absolute and relative cusp area data shows that the major taxonomic distinction in relative cusp area is in the premolars, in which it is apparent that EAFROB are distinguished by their larger buccal cusps. The principal conclusions of the assessment of the specimens in the 'unknown' category is that the postcanine dentitions of a skull, KNM-ER 1805, and a cranium, KNM-ER 1813, are closest in size and shape to EAFHOM. There is no dental evidence to suggest that these specimens should be assigned to A. africanus, the formal taxon making up the SAFGRA category. PMID:3254883

  1. Fifth metatarsal morphology does not predict presence or absence of fibularis tertius muscle in hominids.

    Eliot, D J; Jungers, W L


    The leg muscle fibularis tertius (formerly peroneus tertius) is occasionally absent in humans, but it is rarely found in other primates. Phylogenetically and functionally it appears to be linked to efficient terrestrial bipedalism. An osseous indicator of the muscle would therefore be useful for interpreting the locomotor behavior of fossil hominids. To determine whether the presence of fibularis tertius can be detected osteologically, we isolated 58 human fifth metatarsals, noting which came from cadavers lacking the muscle. The bones were then ranked according to two characters that have been said to suggest presence of fibularis tertius in australopithecines: (1) sharpness of the dorsal shaft edge and (2) size and prominence of the dorsal tubercle. Presence of the muscle showed little association with the ranked characters, and the two criteria were uncorrelated. For example, one individual lacking a fibularis tertius exhibited nearly maximal expression of both features, whereas another possessing the muscle showed the weakest development of both. Only one of the 58 bones had a line comparable to that seen on SK 33380, a robust australopithecine fifth metatarsal from Member 3 of Swartkrans, South Africa. We conclude that fifth metatarsal morphology offers little reliable information about the presence of fibularis tertius or the timing of its appearance in the human career. PMID:10656782

  2. Pliocene and pleistocene hominid-bearing sites from west of lake turkana, kenya.

    Harris, J M; Brown, F H; Leakey, M G; Walker, A C; Leakey, R E


    Pliocene and Pleistocene fossil localities near the western shoreline of Lake Turkana, ranging in age between 1 million and 3.5 million years in age, have produced important new hominid specimens including most of a Homo erectus skeleton and a relatively complete early robust australopithecine cranium. The lacustrine, fluviatile, and terrestrial strata are designated the Nachukui Formation, which is subdivided into eight members. The distribution of sedimentary facies within the Nachukui Formation suggests that, as today, the Labur and Murua Rith ranges formed the western margin of the basin and were drained by eastward-flowing rivers that fed into the forerunner of the present lake or a major river system. There is also stratigraphic evidence for tectonic movement during the deposition of these sediments. Twenty-three of the tuffs observed in the succession occur also in the Koobi Fora Formation east of the lake and in the Shungura Formation of the lower Omo Valley and permit precise correlation among these three localities. Fortyseven fossiliferous sites from West Turkana have yielded more than 1000 specimens of 93 mammalian species. The mammalian fossils represent nine sequential assemblages that augment information about faunal and environmental change from elsewhere in the basin. PMID:17820626

  3. Basicranial anatomy of Plio-Pleistocene hominids from East and South Africa.

    Dean, M C; Wood, B A


    The results of a metrical analysis of the basicranium of 19 Plio-Pleistocene fossil hominid crania are presented. The sample includes crania attributed to Australopithecus africanus, Australopithecus boisei, and robustus, and Homo erectus as well as crania whose attribution is still under discussion. These results confirm significant differences between the cranial base patterns of the "gracile" and "robust" australopithecines and the three crania attributed to Homo erectus have a pattern which resembles that of modern humans. None of the crania examined from East Africa sites have base patterns which resemble that of the "gracile" australopithecines. The crania KNM-ER 407 and 732 have patterns which are compatible with them being smaller-bodied females of Australopithecus boisei; KNM-ER 1470 and 1813 have base patterns which most closely resemble that of Homo erectus. The cranial base pattern of KNM-ER 1805 is compatible with its inclusion in either Australopithecus boisei or Homo. When account is taken of the immaturity of Taung, the evidence of its cranial base pattern suggests that if it had reached adulthood it would have resembled the "gracile" australopithecine crania from Sterkfontein and Makapansgat. PMID:6816071

  4. Geometric morphometric analysis of allometric variation in the mandibular morphology of the hominids of Atapuerca, Sima de los Huesos site.

    Rosas, Antonio; Bastir, Markus


    Allometry is an important factor of morphological integration that contributes to the organization of the phenotype and its variation. Variation in the allometric shape of the mandible is particularly important in hominid evolution because the mandible carries important taxonomic traits. Some of these traits are known to covary with size, particularly the retromolar space, symphyseal curvature, and position of the mental foramen. The mandible is a well studied system in the context of the evolutionary development of complex morphological structures because it is composed of different developmental units that are integrated within a single bone. In the present study, we investigated the allometric variation of two important developmental units that are separated by the inferior nerve (a branch of CN V3). We tested the null hypothesis that there would be no difference in allometric variation between the two components. Procrustes-based geometric morphometrics of 20 two-dimensional (2D) landmarks were analyzed by multivariate regressions of shape on size in samples from 121 humans, 48 chimpanzees, and 50 gorillas (all recent specimens), eight fossil hominids from Atapuerca, Sima de los Huesos (AT-SH), and 17 Neandertals. The findings show that in all of the examined species, there was significantly greater allometric variation in the supra-nerve unit than in the infra-nerve unit. The formation of the retromolar space exhibited an allometric relationship with the supra-nerve unit in all of the species studied. The formation of the chin-like morphology is an "apodynamic" feature of the infra-nerve unit in the AT-SH hominids. The results of this study support the hypothesis that allometry contributes to the organization of variation in complex morphological structures. PMID:15164343

  5. Geometric pattern of the hominoid hallucal tarsometatarsal complex. Quantifying the degree of hallux abduction in early hominids

    Berillon, Gilles


    The degree of hallux abduction in extant and fossil hominoids is analysed in terms of geometric relationships between the first metatarsal and the medial cuneiform and quantified by angular data, in relation to grasping ability and locomotor pattern. The 'australopithecine' pattern corresponds to an abducted first podal ray with some grasping abilities and seems to be derived from a ' Proconsul-like' pattern rather than a 'living African great ape-like' pattern. The Olduvai Hominid 8 condition closely resembles that of the modern human which corresponds to a full bipedalism.

  6. Mandibular postcanine dentition from the Shungura Formation, Ethiopia: crown morphology, taxonomic allocations, and Plio-Pleistocene hominid evolution.

    Suwa, G; White, T D; Howell, F C


    Over 200 hominid specimens were recovered by the International Omo Expedition of 1967-1976. Despite the fragmentary nature of this primarily dental collection, these hominid remains represent a major body of evidence about hominid evolution in eastern Africa during the 2-3 myr time period. Our analysis of the Omo dental collection is based on a large comparative sample of 375 quantifiable mandibular postcanine teeth of A. afarensis, A. africanus, A. aethiopicus, A. boisei, A. robustus, and early Homo. A total of 48 isolated mandibular premolars and molars of the Omo collection spanning the 2-3 myr time period is sufficiently preserved to allow reliable serial allocations and intertaxon comparisons and is the object of study in this paper. We present taxonomic identifications of these teeth and seven other mandibular specimens preserving tooth crowns. Metric analyses of this study include cusp area and crown shape variables taken on occlusal view diagrams. Nonmetric analyses were based on simultaneous observations of all relevant material to ensure accuracy of categorical evaluations. First, a combined metric and morphological evaluation was conducted to allocate each Omo tooth to either robust or nonrobust categories. Further taxonomic affinities were then examined. Our results indicate that nonrobust and robust lineages cooccur by circa 2.7 myr. We consider the Shungura robust specimens from Members C through F to represent A. aethiopicus. A significant phenetic transformation occurs at circa 2.3 myr, with the mosaic emergence of the derived A. boisei morphology across Member G times. Characterization of the East African nonrobust lineage is more difficult because of the comparatively subtle morphological differences seen among the dentitions of A. afarensis, A. africanus, and early Homo. The earlier Members B and C nonrobust specimens are difficult to evaluate and are considered indeterminate to genus or species. Both molars and premolars from Members E through G

  7. Sexual dimorphism in the Atapuerca-SH hominids: the evidence from the mandibles.

    Rosas, Antonio; Bastir, Markus; Martínez-Maza, Cayetana; Bermúdez de Castro, Jose María


    The pattern of sexual dimorphism in 15 mandibles from the Atapuerca-SH Middle Pleistocene site, attributed to Homo heidelbergensis, is explored. Two modern human samples of known sex are used as a baseline for establishing sexing criteria. The mandible was divided for analysis into seven study regions and differential expression of sexual dimorphism in these regions is analysed. A total of 40 continuous and 32 discrete variables were scored on the mandibles. The means method given in Regh & Leigh (Am. J. phys. Anthrop.110, 95-104, 1999) was followed for evaluating the potential of correct sex attribution for each variable. On average, the mandibles from the Atapuerca-SH site present a degree of sexual dimorphism about eight points higher than in H. sapiens samples. However, mandibular anatomy of the European Middle Pleistocene hominid records sexual dimorphism differentially. Different areas of the Atapuerca-SH mandibles exhibit quite distinct degrees of sexual dimorphism. For instance, variables of the alveolar arcade present very low or practically no sexual dimorphism. Variables related to overall size of the mandible and symphysis region present a medium degree of sex differences. Finally, ramus height, and gonion and coronoid process present a high degree of sexual dimorphism (indexes of sexual dimorphism are all above 130%). Whether this marked sexual dimorphism in specific anatomical systems affects sexual differences in body size is not completely clear and further studies are needed. Sexual differences detected in the mandible of modern humans have at least two components: differences related to musculo-skeletal development and differences related to a different growth trajectory in males and females (relative development of some of the basal border features). The Atapuerca-SH mandibles display little variation in the basal border, however. The limited variation of this mandibular region may indicate that the pattern of sexual variation in H

  8. New hominid fossils from Woranso-Mille (Central Afar, Ethiopia) and taxonomy of early Australopithecus.

    Haile-Selassie, Yohannes; Saylor, Beverly Z; Deino, Alan; Alene, Mulugeta; Latimer, Bruce M


    The phylogenetic relationship between Australopithecus anamensis and Australopithecus afarensis has been hypothesized as ancestor-descendant. However, the weakest part of this hypothesis has been the absence of fossil samples between 3.6 and 3.9 million years ago. Here we describe new fossil specimens from the Woranso-Mille site in Ethiopia that are directly relevant to this issue. They derive from sediments chronometrically dated to 3.57-3.8 million years ago. The new fossil specimens are largely isolated teeth, partial mandibles, and maxillae, and some postcranial fragments. However, they shed some light on the relationships between Au. anamensis and Au. afarensis. The dental morphology shows closer affinity with Au. anamensis from Allia Bay/Kanapoi (Kenya) and Asa Issie (Ethiopia) than with Au. afarensis from Hadar (Ethiopia). However, they are intermediate in dental and mandibular morphology between Au. anamensis and the older Au. afarensis material from Laetoli. The new fossils lend strong support to the hypothesized ancestor-descendant relationship between these two early Australopithecus species. The Woranso-Mille hominids cannot be unequivocally assigned to either taxon due to their dental morphological intermediacy. This could be an indication that the Kanapoi, Allia Bay, and Asa Issie Au. anamensis is the primitive form of Au. afarensis at Hadar with the Laetoli and Woranso-Mille populations sampling a mosaic of morphological features from both ends. It is particularly difficult to draw a line between Au. anamensis and Au. afarensis in light of the new discoveries from Woranso-Mille. The morphology provides no evidence that Au. afarensis and Au. anamensis represent distinct taxa. PMID:19918995

  9. Analysis of the dental morphology of Plio-Pleistocene hominids. III. Mandibular premolar crowns.

    Wood, B A; Uytterschaut, H


    Accurate measurements were made of the overall size of both the crown and its components of 91 mandibular premolar teeth of early hominids. The shape of the crown outline and the fissure pattern, and the expression of four morphological traits, were also recorded. Non-dental criteria were used to allocate the specimens into four major taxonomic categories (EAFROB, EAFHOM, SAFROB and SAFGRA), approximating to the hypodigms of, respectively, A. boisei, H. habilis and Homo sp., A. robustus and A. africanus. Those specimens that could not be so allocated were regarded as 'unknown'. Intertaxonomic overall size differences were established for both the P3 and P4, with the latter showing little overlap in crown size between the three taxonomic categories usually associated with East African sites (i.e. EAFROB, EAFHOM and SAFGRA). Crown shape is a better discriminator between taxonomic groups for P3 than for P4, with the P3s of EAFHOM showing less buccolingual expansion than the other taxonomic categories. Cusp number, the location of the lingual cusp and the expression of the median longitudinal fissure, show systematic variation between the main taxonomic categories, with the 'robust' taxa being distinguished by additional distal cusps, and a more deeply incised median longitudinal fissure, and EAFHOM being peculiar in having a distally situated lingual cusp. Marginal grooves show more overlap in their incidence and expression between taxonomic categories. Both the 'robust' australopithecine taxonomic categories have relatively large talonids, apparently at the expense of the size of the buccal cusp. The relative talonid enlargement was greater for P3 than for P4, a conclusion which is at variance with previous published assessments. Investigation of the allometric relationships between relative talonid size and overall crown size in the pooled 'non-robust' taxonomic categories did not suggest that talonid enlargement was a simple consequence of a larger-size crown. The

  10. Effects of size and locomotor adaptations on the hominid pelvis: evaluation of australopithecine bipedality with a new multivariate method.

    Berge, C; Kazmierczak, J B


    Three pelves and eight innominate bones belonging to the fossil species, Australopithecus africanus, Australopithecus robustus, Homo erectus, and Homo sapiens, have been studied biometrically and compared with those of recent humans and apes. A new method of logarithmic factorial analysis suppresses both the size effects and the size reference on pelvic proportions. In combination with principal component analysis it allows specializations to be dissociated from allometrical variations. Some morphological differences on the hominid pelvis prove to be mainly allometric. However, the pelvic morphology of australopithecines is clearly differentiated from that of the genus Homo (including H. erectus, OH 28, KNMER 3227). A. africanus (Sts 14, MLD 7, AL 288) is nearer the humans than is A. robustus (SK 50, SK 3155), which appears to be more specialized in the australopithecine lineage. The pelvic morphology of A. africanus, as integrated with the articular pelvic-femoral link, appears to be biometrically equivalent to that of humans. PMID:3104176

  11. Cut marks and terminal Pleistocene hominids in the Ma'anshan site:Evidence for meat-eating

    ZHANG Yue; WANG ChunXue; ZHANG ShuangQuan; GAO Xing


    In this paper,cut marks on the long bones of class Ⅱ sized animals in the Ma'anshann site are studied.Based on the location and frequencies of the long bone cut marks,the distribution characteristics are analyzed as follows:(1) cut mark frequencies in the lower layer (LL) are much higher than those of the upper;(2) in the LL cut mark frequency of the upper limbs is the highest,and that of the middle and lower limbs is lower and the lowest;(3) In the upper layer (UL) the cut mark frequency,does not spread as orderly as in the LL.The data are compared to those of the experiment and it is demonstrated that values of the LL all fall into the experimental 95% confidence intervals,and the cut mark frequencies of the upper,middle and lower limbs coincide with those of the experiment;while the values of the UL are much lower,of which,those of the humerus,femur and radius are out of the intervals,and the frequencies of the upper,middle and lower limbs are far more different from those of the experiment.It implies that the earlier hominids (of the LL) defleshed the limbs of the class Ⅱ sized animals with stone tools more completely than the later hominids.With the evidence of burning marks,it is suggested that the difference on the roasting behaviors derived the cut mark difference of the Ma'anshan UL and LL.

  12. The Sima de los Huesos hominids date to beyond U/Th equilibrium (>350 kyr) and perhaps to 400-500 kyr: New radiometric dates

    Bischoff, J.L.; Shamp, D.D.; Aramburu, Arantza; Arsuaga, J.L.; Carbonell, E.; Bermudez de Castro, Jose Maria


    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud breccia underlying an accumulation of the Middle Pleistocene cave bear (U. deningeri). Earlier dating estimates of 200 to 320 kyr were based on U-series and ESR methods applied to bones, made inaccurate by unquantifiable uranium cycling. We report here on a new discovery within the Sima de los Huesos of human bones stratigraphically underlying an in situ speleothem. U-series analyses of the speleothem shows the lower part to be at isotopic U/Th equilibrium, translating to a firm lower limit of 350 kyr for the SH hominids. Finite dates on the upper part suggest a speleothem growth rate of c. 1 cm/32 kyr. This rate, along with paleontological constraints, place the likely age of the hominids in the interval of 400 to 600 kyr. ?? 2002 Elsevier Science Ltd. All rights reserved.

  13. Longitudinal study of dental development in chimpanzees of known chronological age: implications for understanding the age at death of Plio-Pleistocene hominids.

    Anemone, R L; Mooney, M P; Siegel, M I


    Reconstruction of life history variables of fossil hominids on the basis of dental development requires understanding of and comparison with the pattern and timing of dental development among both living humans and pongids. Whether dental development among living apes or humans provides a better model for comparison with that of Plio-Pleistocene hominids of the genus Australopithecus remains a contentious point. This paper presents new data on chimpanzees documenting developmental differences in the dentitions of modern humans and apes and discusses their significance in light of recent controversies over the human or pongid nature of australopithecine dental development. Longitudinal analysis of 299 lateral head radiographs from 33 lab-reared chimpanzees (Pan troglodytes) of known chronological age allows estimation of means and standard deviations for the age at first appearance of 8 developmental stages in the mandibular molar dentition. Results are compared with published studies of dental development among apes and with published standards for humans. Chimpanzees are distinctly different from humans in two important aspects of dental development. Relative to humans, chimpanzees show advanced molar development vis a vis anterior tooth development, and chimpanzees are characterized by temporal overlap in the calcification of adjacent molar crowns, while humans show moderate to long temporal gaps between the calcification of adjacent molar crowns. In combination with recent work on enamel incremental markers and CAT scans of developing dentitions of Plio-Pleistocene hominids, this evidence supports an interpretation of a rapid, essentially "apelike" ontogeny among australopithecines. PMID:8928715

  14. The diets of ungulates from the hominid fossil-bearing site of Elandsfontein, Western Cape, South Africa

    Stynder, Deano D.


    The dietary regimes of 15 ungulate species from the middle Pleistocene levels of the hominid-bearing locality of Elandsfontein, South Africa, are investigated using the mesowear technique. Previous studies, using taxonomic analogy, classified twelve of the studied species as grazers ( Redunca arundinum, Hippotragus gigas, Hippotragus leucophaeus, Antidorcas recki, Homoiceras antiquus, Damaliscus aff. lunatus, Connochaetes gnou laticornutus, Rabaticerus arambourgi, Damaliscus niro, Damaliscus sp. nov., an unnamed "spiral horn" antelope and Equus capensis), one as a mixed feeder ( Taurotragus oryx) and two as browsers ( Tragelaphus strepsiceros and Raphicerus melanotis). Although results from mesowear analysis sustain previous dietary classifications in the majority of cases, five species were reclassified. Three species previously classified as grazers, were reclassified as mixed feeders ( H. gigas, D. aff. lunatus and R. arambourgi), one previously classified as a grazer, was reclassified as a browser (the "spiral horn" antelope), and one previously classified as a mixed feeder, was reclassified as a browser ( T. oryx). While current results broadly support previous reconstructions of the Elandsfontein middle Pleistocene environment as one which included a substantial C 3 grassy component, the reclassifications suggest that trees, broad-leaved bush and fynbos were probably more prominent than what was previously thought.

  15. Shadows on a changing landscape: comparing nesting patterns of hominids and chimpanzees since their last common ancestor.

    Sept, J


    Studying the evolution of nesting behavior within the human-chimpanzee clade is problematic because evidence is sparse and difficult to interpret. Lacking a fossil or archaeological record for proto-chimpanzees, reconstructions of the antecedents of modern chimp nesting patterns can be reconstructed only from careful studies of variation in current chimpanzee and bonobo nesting patterns within the context of spatial and temporal landscape parameters. The ethology of nesting also provides an important frame of reference for reconstructions of early hominid nesting behavior. If the contemporary contrast between human and chimpanzee nesting patterns is seen as an evolutionary dichotomy, then African prehistoric landmarks that mark the origin of this split might include bipedalism and the origins of the hominidae, the first stone tools and the origins of Homo, the developmental and behavioral adaptations of Homo ergaster, shifts in Late Acheulian settlement patterns, and the origins of anatomically modern humans and the Middle Stone Age. The issue of whether Early Stone Age archaeological sites were used for nesting is unresolved because potential markers of such behavior, such as hearths, structures, or bedding, are not unambiguously recognizable in the archaeological record until the Middle Stone Age. PMID:9730215

  16. Multivariate analysis of the sexual dimorphism of the hip bone in a modern human population and in early hominids.

    Arsuaga, J L; Carretero, J M


    A large sample of hip bones of known sex coming from one modern population is studied morphologically and by multivariate analysis to investigate sexual dimorphism patterns. A principal component analysis of raw data shows that a large amount of the hip bone sexual dimorphism is accounted for by size differences, but that sex-linked shape variation is also very conspicuous and cannot be considered an allometric consequence of differences in body size between the sexes. The PCA of transformed ("shape") variables indicates that the female hip bones are different in those traits associated with a relatively larger pelvic inlet (longer pubic bones, a greater degree of curvature of the iliopectineal line, and more posterior position of the auricular surface), as well as a broader sciatic notch. The analysis of nonmetric traits also shows marked sexual dimorphism in the position of the sacroiliac joint in the iliac bone, in the shape of the sciatic notch, in pubic morphology, and in the presence of the pre-auricular sulcus in females. When the australopithecine AL 288-1 and Sts 14 hip bones are included in the multivariate analysis, they appear as "ultra-females." In particular these early hominids exhibit extraordinarily long pubic bones and iliopectineal lines, which cannot be explained by allometry. PMID:8147439

  17. Early hominid dental pathology: interproximal caries in 1.5 million-year-old Paranthropus robustus from Swartkrans.

    Grine, F E; Gwinnett, A J; Oaks, J H


    Carious lesions on the mesial and distal aspects of a RM1 of a young adult 'robust' australopithecine. Paranthropus robustus, are described. The specimen is from Member 1 sediments of the Swartkrans cave, which are dated to between about 1.8 and 1.5 million years before present. The mesial lesion, located cervically, had progressed further than the two distal lesions, which were situated along the cervix and in the enamel of the interproximal contact facet. This is the third specimen of P. robustus to be discovered with dental caries, but the other two cases were associated with occlusal and buccal enamel hypoplasia. Caries is present in less than about 3.0% of the approx. 116-128 P. robustus specimens at Swartkrans, and this incidence is noticeably lower than in the small Homo erectus sample from the same site. While this difference may simply be a sampling artefact, it may reflect dietary differences between these two synchronic and presumably sympatric early hominid species. PMID:2196866

  18. Stable isotope analyses of tooth enamel carbonate of large herbivores from the Tugen Hills deposits: Palaeoenvironmental context of the earliest Kenyan hominids

    Roche, Damien; Ségalen, Loïc; Senut, Brigitte; Pickford, Martin


    Understanding shifts in past climatic and environmental conditions are crucial for throwing light on human evolution. Available reconstructions of the palaeoecology of faunal and floral assemblages indicate that the earliest Kenyan hominids, including Orrorin tugenensis, are associated with forest landscapes. In this study, we present stable isotope data of tooth enamel carbonate of large herbivores associated with these hominids in order further to evaluate their environmental context. Fossil teeth were sampled in the Lukeino Formation (6.1-5.7 Ma, Late Miocene) and the Mabaget Formation (5.3-4.5 Ma, Early Pliocene) at the foot of the Tugen Hills (Great Rift Valley). Despite chemical changes in fossil enamel, preservation of the palaeoenvironmental signals is supported by the difference in δ18O between hippos and terrestrial fauna. Moreover, the giraffid specimen from the Mabaget Formation exhibits one of the highest δ18O values, as expected for a drought-tolerant animal. The δ13C of large herbivores indicates that the earliest Kenyan hominids inhabited a mixed C3-C4 environment as did Ardipithecus (Ethiopia) and Sahelanthropus (Chad), two early putative hominids. The Tugen Hills might have been a wooded grassland with patches of woodland. There is no record of closed-canopy forest at the time of deposition. We emphasize differences in food habits among herbivore groups. Deinotheres, nearly all elephantids and the giraffid individual had a C3 diet which reflected browsing behaviour. The intake of C4 plants prevailed for equids and gomphotheres and was consistent with grazing habits. Most hippos and suids were mixed C3-C4 feeders and consequently were generalist herbivores. Bovids and rhinos had a diet ranging from C3 to C4 plants. Variations in δ13C and δ18O among faunal assemblages suggest changes in local climate and vegetation. Moister conditions likely occurred in the Early Pliocene and the latest Miocene (ca. 5.7 Ma) than before. The C3 plant biomass

  19. Combined ESR/U-series chronology of Acheulian hominid-bearing layers at Trinchera Galeria site, Atapuerca, Spain

    The Sierra de Atapuerca, northern Spain, is known from many prehistoric and paleontologic sites documenting human prehistory in Europe. Three major sites, Gran Dolina, Galeria and Sima del Elefante, range in age from the oldest hominin of Western Europe dated to 1.1 to 1.3 Ma (millions of years ago) at Sima del Elefante to c.a. 0.2 Ma on the top of the Galeria archaeological sequence. Recently, a chronology based on luminescence methods (Thermoluminescence [TL] and Infrared Stimulated Luminescence [IRSL]) applied to cave sediments was published for the Gran Dolina and Galeria sites. The authors proposed for Galeria an age of 450 ka (thousands of years ago) for the units lower GIII and GII, suggesting that the human occupation there is younger than the hominid remains of Sima de los Huesos (≥530 ka) around 1 km away. In this paper, we present new results obtained by combined Electron Spin Resonance/Uranium-series (ESR/U-series) dating on 20 herbivorous teeth from different levels at the Galeria site. They are in agreement with the TL results for the upper part of the stratigraphic sequence (GIV and GIIIb), in the range of between 200 and 250 ka. But for the GIIIa to GIIb levels, the TL ages become abruptly older by 200 ka while ESR ages remain relatively constant. Finally, the TL and ESR data agree in the lowest part of the section (GIIa); both fall in the range of around 350-450 ka. Our results suggest a different interpretation for the GII, GIII and GIV units of Galeria and the upper part of Gran Dolina (TD10 and TD11) than obtained by TL. The ESR/U-series results are supported by a Bayesian analysis, which allows a better integration between stratigraphic information and radiometric data. (authors)

  20. Alluvial systems as archives for environmental change at a Hominid site with Oldowan archaeological occurrences: the Homa Peninsula, southwestern Kenya

    Vincent, Thomas; Whitfield, Elizabeth; Kirby, Jason; Hunt, Christopher; Bishop, Laura; Plummer, Thomas; Ditchfield, Peter


    The Homa Peninsula, southwestern Kenya, preserves fossiliferous sedimentary sequences dating to the Plio-Pleistocene. Evidence of hominids inhabiting an open grassland setting and utilising Oldowan tools has been reported here, as well as some of the oldest known traces of hominin activity. Reconstructions of the palaeoenvironment have suggested that alluvial and lake marginal environments on a grassy plain, between wooded slopes and a permanent water body might be plausible. However, these interpretations are based only on field sedimentological analyses and stable isotope analysis at a single site on the peninsula (Kanjera South). It is the aim of this study to utilise a multiproxy approach to develop our understanding of the palaeoenvironmental characteristics here. Sediments will also be characterized at a new site (Nyayanga) through field analyses, as well as through analyses of particle size, siliceous microfossils (diatoms, phytoliths and sponge spicules), pollen and stable isotopes. By utilizing this approach, new insights into the palaeoecology, palaeohydromorphology and palaeoclimate of the locale may be revealed, expanding the limited data available to palaeoanthropological studies of Oldowan occurrences in east Africa. Efforts to refine palaeoenvironmental reconstructions of Kanjera South through particle size analysis have shown that sediments in the lower beds of the sequence are characterised by poor sorting, a bimodal distribution and sand/silty-sand grade material. This suggests rapid deposition and/or a variable hydrological regime and may represent the role of relatively unconfined ephemeral channels in the transportation and deposition of sediments. Fluvial reworking of aeolian sediments, most likely during unconfined flood events may also have occurred.

  1. Functional Divergence of the Nuclear Receptor NR2C1 as a Modulator of Pluripotentiality During Hominid Evolution.

    Baker, Jennifer L; Dunn, Katherine A; Mingrone, Joseph; Wood, Bernard A; Karpinski, Beverly A; Sherwood, Chet C; Wildman, Derek E; Maynard, Thomas M; Bielawski, Joseph P


    Genes encoding nuclear receptors (NRs) are attractive as candidates for investigating the evolution of gene regulation because they (1) have a direct effect on gene expression and (2) modulate many cellular processes that underlie development. We employed a three-phase investigation linking NR molecular evolution among primates with direct experimental assessment of NR function. Phase 1 was an analysis of NR domain evolution and the results were used to guide the design of phase 2, a codon-model-based survey for alterations of natural selection within the hominids. By using a series of reliability and robustness analyses we selected a single gene, NR2C1, as the best candidate for experimental assessment. We carried out assays to determine whether changes between the ancestral and extant NR2C1s could have impacted stem cell pluripotency (phase 3). We evaluated human, chimpanzee, and ancestral NR2C1 for transcriptional modulation of Oct4 and Nanog (key regulators of pluripotency and cell lineage commitment), promoter activity for Pepck (a proxy for differentiation in numerous cell types), and average size of embryological stem cell colonies (a proxy for the self-renewal capacity of pluripotent cells). Results supported the signal for alteration of natural selection identified in phase 2. We suggest that adaptive evolution of gene regulation has impacted several aspects of pluripotentiality within primates. Our study illustrates that the combination of targeted evolutionary surveys and experimental analysis is an effective strategy for investigating the evolution of gene regulation with respect to developmental phenotypes. PMID:27075724

  2. ESR analyses on tooth enamel from the Paleolithic layers at the Obi-Rakhmat hominid site, Uzbekistan: Tackling a dating controversy

    Skinner, Anne R. [Department of Chemistry, Williams College, Williamstown, MA 01267 (United States); RFK Science Research Institute, Glenwood Landing, NY, 11547 (United States)], E-mail:; Blackwell, Bonnie A.B. [Department of Chemistry, Williams College, Williamstown, MA 01267 (United States); RFK Science Research Institute, Glenwood Landing, NY, 11547 (United States)], E-mail:; Mian, Abubakar; Baboumian, Shaunte M. [RFK Science Research Institute, Glenwood Landing, NY, 11547 (United States); Blickstein, Joel I.B. [Department of Chemistry, Williams College, Williamstown, MA 01267 (United States); RFK Science Research Institute, Glenwood Landing, NY, 11547 (United States); Wrinn, Patrick J. [Department of Anthropology, University of Arizona, Tucson, AZ, 85721-0030 (United States)], E-mail:; Krivoshapkin, A.I.; Derevianko, A.P. [Institute of Archaeology and Ethnography, Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation); Lundburg, Joyce A. [Department of Geography, Carleton University, Ottawa, ON, K1S 5B6 (Canada)], E-mail:


    In the Tien Shan Mt., northeastern Uzbekistan, the Obi-Rakhmat rockshelter has yielded newly discovered hominid remains associated with an abundant Paleolithic industry and a rich faunal assemblage in typical cave fill sediment. Eight bovid teeth were dated by standard and isochron ESR to resolve the 50 ky discrepancy between the {sup 14}C and {sup 234}Th/{sup 234}U ages for Obi-Rakhmat. All the dentine contained high U concentrations, up to 150 ppm. External dose rates of 470-820{mu}Gy/y were calculated from volumetrically averaged sediment geochemistry for all layers and mineralogies within 30 cm of the teeth. One tooth from Layer 12.3 averaged 57{+-}2ka assuming linear U uptake, while three from Layer 13 averaged 66{+-}2ka, that from Layer 14.3,73{+-}4ka, and three from Layer 21.2,87{+-}4ka. Isochron and {sup 230}Th/{sup 234}U analyses suggest that the teeth did experience linear uptake with {approx}5% recent secondary U remobilization. These dates indicate that the site was inhabitted during Oxygen Isotope Stages (OIS) 5a-4, as climates were generally cooling, but beginning to fluctuate more widely. Assuming a constant sedimentation rate of 22 cm/ky, the hominid remains date to {approx}74ka.

  3. (40)Ar/(39)Ar dating, paleomagnetism, and tephrochemistry of Pliocene strata of the hominid-bearing Woranso-Mille area, west-central Afar Rift, Ethiopia.

    Deino, Alan L; Scott, Gary R; Saylor, Beverly; Alene, Mulugeta; Angelini, Joshua D; Haile-Selassie, Yohannes


    (40)Ar/(39)Ar dating of tuffs and mafic lavas, tephra geochemistry, and paleomagnetic reversal stratigraphy have been used to establish the chronostratigraphy of the Pliocene hominid-bearing fossiliferous succession at Woranso-Mille, a paleontological study area in the western part of the central Afar region of Ethiopia. The succession in the northwestern part of the study area ranges in (40)Ar/(39)Ar age from 3.82-3.570 Ma, encompassed by paleomagnetic subchron C2Ar (4.187-3.596 Ma). One of the major tuff units, locally named the Kilaytoli tuff, is correlative on the basis of age and geochemistry to the Lokochot Tuff of the Turkana Basin. A hominid partial skeleton (KSD-VP-1) was found in strata whose precise stratigraphic position and age is still under investigation, but is believed to correspond to the later part of this interval. Woranso-Mille fills a significant gap in the fossil record of northeastern Africa at the time of the lower to middle Pliocene transition, when many extant species lineages of African fauna were established. PMID:20034653

  4. Estimate of the lower-limb-specific muscle parameters during bipedal walking for humans, apes and early hominids with the implications for the evolution of body proportion

    Wang Weijie


    Modern human has different body proportion from early hominids and great apes. Comparing with others, in general, modern human adults have relatively long lower limb and heavier body weight. Since the lower limbs provide support to the whole body and play an important role in walking, it is proposed that the ratio of the lower limb to the whole body for modern human could be beneficial to bipedal walking. This study tried to estimate the muscle parameters of the lower limb in walking for the subjects with various body proportions. Using a simplified musculoskeletal model, some muscle parameters of the lower limb, e.g. muscle force, stress, work and power, were estimated for modern human adult, child, AL 288-1 (the fossil specimens of Australopithecus afarensis, 3.18 million years old) and apes. The results show that with the body proportion modern human adult spends less muscle work and power in walking than other subjects. The results imply that using the cost of transport (i.e. the muscle work of the lower limb per unit of displacement) as the criteria, the early hominids, if their body proportions were structurally similar to AL 288-1, could evolve towards what modern human adult looks like, in order to save energy during bipedal walking.

  5. An integrated approach to taphonomy and faunal change in the Shungura formation (Ethiopia) and its implication for hominid evolution.

    Alemseged, Zeresenay


    Environmental and faunal changes through time have been recorded for many African Plio-Pleistocene sites. Fossil evidence suggests that there is a continuous, if not uniform, transformation of the fauna and flora from the Pliocene through the end of Pleistocene. However, discerning major biotic turnovers and linking them to global and regional climatic changes have been complicated by many factors, notably taphonomy and discontinuity of the fossil evidence, notwithstanding the considerable work of some researchers (e.g., Vrba, E.S., 1988. Late Pliocene climatic events and hominid evolution, in: Grine, F. (Ed.), Evolutionary History of the "Robust" Australopithecines. De Gruyter, New York, pp. 405-426, Vrba, E.S., 1995. The fossil record of African (Mammalia, Bovidae) in relation to human evolution and paleoclimate, in: Vrba, E.S., Denton, G.H., Partridge, T.C., Burkle, L.H. (Eds.), Paleoclimate and Evolution, with Emphasis on Human Origins. Yale University Press, New Haven, pp. 385-424). A sample of over 22,000 fossils collected by the French Omo Expedition, from the Shungura Formation of Ethiopia, was analyzed using an integrated approach to investigate taphonomic and faunal change patterns. The following results are obtained: (1) Univariate and multivariate studies support continuous faunal change from Member A through Member G of the Shungura sequence; (2) Correspondence analysis (CA) on extant bovids in African game parks shows that bovid tribes and genera are generally characterized by habitat specificity; (3) Taphonomic studies demonstrate that the relative abundance of different skeletal elements varies according to depositional environment; (4) CA on 73 localities of the Shungura Formation and 19 mammalian taxa points to a major faunal change around the base of Member G dated to ca. 2.3 Ma. This transformation is characterized by a change to open and edaphic grassland as a dominant type of environment; (5) This major faunal change correlates in time with

  6. Hétérochronies dans l'évolution des hominidés. Le développement dentaire des australopithécines «robustes»Heterochronic process in hominid evolution. The dental development in 'robust' australopithecines.

    Ramirez Rozzi, Fernando V.


    Heterochrony is defined as an evolutionary modification in time and in the relative rate of development [6]. Growth (size), development (shape), and age (adult) are the three fundamental factors of ontogeny and have to be known to carry out a study on heterochronies. These three factors have been analysed in 24 Plio-Pleistocene hominid molars from Omo, Ethiopia, attributed to A. afarensis and robust australopithecines ( A. aethiopicus and A. aff. aethiopicus) . Molars were grouped into three chronological periods. The analysis suggests that morphological modifications through time are due to heterochronic process, a neoteny ( A. afarensis - robust australopithecine clade) and a time hypermorphosis ( A. aethiopicus - A. aff. aethiopicus).

  7. Quantification de révolution morphologique du crâne des Hominidés et hétérochronies

    Chaline, Jean; David, Bruno; Magniez-Jannin, Françoise; Malassé, Anne Dambricourt; Marchand, Didier; Courant, Frédéric; Millet, Jean-Jacques


    Comparisons of adult skulls of various species of great apes, fossil hominids and modern humans in the sagittal, Francfort and ortho-sagittal planes reveal a series of three separate organisation plans: 'Great Ape', 'Australopithecine' and 'Homo', the latter including primitive men ( Homo ergaster-erectus-neandertalensis) and modern humans ( Homo sapiens). Morphological changes between these plans are quantified for the first time here by vector fields. This study confirms the existence of cranio-facial contraction, which occurs as a series of leaps. The juvenile morphology of the great ape skull is broadly preserved in adult Homo sapiens, suggesting that numerous heterochronies have occurred in mosaic during ontogeny (hypermorphosis, hypomorphosis, post-displacements).

  8. Réflexion sur le processus coracoïde des hominoïdes et des atèles ; application à quelques hominidés fossiles

    Voisin, Jean-Luc


    Remark on the coracoid process of hominoids and spider monkeys, application to some hominid fossils. The orientation of the coracoid process, in relation to the scapula, is different in man on one hand and other hominoids (Pan, Gorilla, Pongo, Hylobates), spider and colobus monkeys on the other hand. On the contrary, the orientation of the coracoid process is similar in all hominoids and spider monkeys when it is taken in relation to the axial skeleton. Morphology of the coracoid process reve...

  9. Nuevo esquema estratigráfico para los depósitos marinos mio-pliocenos del área de Navidad (33º00'-34º30'S, Chile central New stratigrafic scheme for the Mio-Pliocene marine deposits of the Navidad area (33º00'-34º30'S, central Chile

    Alfonso Encinas


    Full Text Available Varios autores han propuesto diferentes esquemas estratigráficos para los depósitos sedimentarios neógenos marinos que afloran en la zona costera de Chile central entre Valparaíso (~33°00'S y Punta Topocalma (~34°30'S, sin que exista un consenso al respecto. Tampoco existe acuerdo respecto a las correlaciones entre los depósitos que afloran en la parte norte de dicha zona, entre Valparaíso y San Antonio (~33°30'S con aquellos que aparecen en la parte sur, entre San Antonio y Punta Topocalma. Sobre la base de nuevos estudios estratigráficos, sedimentológicos y paleontológicos se propone, de manera formal, un nuevo esquema estratigráfico para estos depósitos. De acuerdo con este nuevo esquema se definen la Formación Navidad (Mioceno Superior-Plioceno Inferior y las formaciones Licancheu, Rapel y La Cueva (Plioceno. Se propone la elevación de las tres primeras unidades (Navidad, Licancheu y Rapel, generalmente consideradas como miembros en clasificaciones anteriores, al rango de formaciones debido a que se encuentran separadas por discontinuidades (paraconformidades de escala regional. En el presente trabajo se definen estas unidades, se revisan los esquemas anteriores y se justifica la proposición de este nuevo esquemaDifferent stratigraphic schemes have been proposed by various authors for the Neogene marine sedimentary deposits cropping out along the central Chilean coast between Valparaíso (~33°00'S and Punta Topocalma (~34°30'S, without any consensus having been reached. Neither does any agreement exist with respect to the correlation between the deposits cropping out in the northern part of this area, between San Antonio (~33°30'S and Valparaíso, and those of the southern part, between San Antonio and Punta Topocalma. Based on new stratigraphic, sedimentologic and paleontologic studies we propose a formal, new stratigraphic classification for this area. According to this scheme we define the Navidad Formation (Upper Miocene-Lower Pliocene and the Licancheu, Rapel and La Cueva formations (Pliocene. We propose that the rank of the three first cited units (Navidad, Licancheu and Rapel, generally considered to be members in previous classifications, be elevated to formations, because they are separated by regional unconformities (paraconformities. In this paper we define these units, revise the previous classifications, and explain the basis for the new classification

  10. High-resolution U-series dates from the Sima de los Huesos hominids yields 600 +∞-66: implications for the evolution of the early Neanderthal lineage

    Bischoff, James L.; Williams, Ross W.; Rosenbauer, Robert J.; Aramburu, Arantza; Arsuaga, Juan Luis; Garcia, Nuria; Cuenca-Bescos, Gloria


    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud-breccia underlying an accumulation of the Middle Pleistocene cave bear (Ursus deningeri). We report here on new high-precision dates on the recently discovered speleothem SRA-3 overlaying human bones within the Sima de los Huesos. Earlier analyses of this speleothem by TIMS (thermal-ionization mass-spectrometry) showed the lower part to be indistinguishable from internal isotopic equilibrium at the precision of the TIMS instrumentation used, yielding minimum age of 350 kyr (kyr = 103 yr before present). Reanalysis of six samples of SRA-3 by inductively-coupled plasma-multicollector mass-spectrometry (ICP-MS) produced high-precision analytical results allowing calculation of finite dates. The new dates cluster around 600 kyr. A conservative conclusion takes the lower error limit ages as the minimum age of the speleothem, or 530 kyr. This places the SH hominids at the very beginnings of the Neandertal evolutionary lineage.

  11. A reassessment of the study of cut mark patterns to infer hominid manipulation of fleshed carcasses at the Flk Zinj 22 site, Olduvai Gorge, Tanzania

    Domínguez-Rodrigo, Manuel


    Full Text Available Previous experimental studies on cut marks have suggested that cut mark percentages and their anatomical distribution (based on element type and bone section type could be used to differentiate primary access to fleshed carcasses from secondary access to defleshed carcasses. In this study, the experimental sample of this type of studies is increased and further data are included to infer a primary access by hominids to carcasses at the FLK Zinj site of Olduvai.

    Estudios experimentales anteriores sobre marcas de corte han sugerido que los porcentajes de marcas de corte y su distribución (basada en tipo de hueso y tipo de sección ósea podrían usarse para diferenciar un acceso primario a carcasas con carne de un acceso secundario a carcasas descarnadas. En este estudio semejante muestra experimental se ve ampliada y se muestran más datos que sirven para inferir que los homínidos tuvieron un acceso primario a las carcasas representadas en el yacimiento FLK Zinj de Olduvai.

  12. Freshwater on the route of hominids "out of Africa" during the last interglacial revealed by U-Th in northern Red Sea fossil reefs

    Lazar, B.; Stein, M.; Agnon, A.; Shaked, Y.


    The migration of Anatomically Modern Hominids (AMH) "out of Africa" is a fundamental problem in the study of human culture concerning that the route passed through the presently hyperarid deserts surrounding the Red Sea. Here, we outline the evidence for significant presence of freshwater in a well developed phreatic coastal aquifer along the Red Sea shores during the last interglacial period. The fringing coral reefs were tectonically uplifted through the freshwater lens resulting in extensive recrystallization of reef framework from the primary aragonite into calcite. We developed a novel open-system U-Th dating methodology that enabled us estimating two ages for the calcitic reef terrace: 1. The original age of the reef terrace, deposited at ~190 ka BP; and 2. the time of freshwater recrystallization (from the primary aragonite into calcite) at ~140 ka BP. The age of freshwater recrystallization is consistent with other geological lines of evidence placing the time of AMH migration "out of Africa" at the onset of the last interglacial. It is likely therefore that during that time the hyperarid Red Sea area was wetter than today facilitating the migration of AMH to Europe and Asia.

  13. Combined ESR/U-series chronology of Acheulian hominid-bearing layers at Trinchera Galería site, Atapuerca, Spain.

    Falguères, Christophe; Bahain, Jean-Jacques; Bischoff, James L; Pérez-González, Alfredo; Ortega, Ana Isabel; Ollé, Andreu; Quiles, Anita; Ghaleb, Bassam; Moreno, Davinia; Dolo, Jean-Michel; Shao, Qingfeng; Vallverdú, Josep; Carbonell, Eudald; Bermúdez de Castro, Jose María; Arsuaga, Juan Luis


    The Sierra de Atapuerca, northern Spain, is known from many prehistoric and palaeontological sites documenting human prehistory in Europe. Three major sites, Gran Dolina, Galería and Sima del Elefante, range in age from the oldest hominin of Western Europe dated to 1.1 to 1.3 Ma (millions of years ago) at Sima del Elefante to c.a. 0.2 Ma on the top of the Galería archaeological sequence. Recently, a chronology based on luminescence methods (Thermoluminescence [TL] and Infrared Stimulated Luminescence [IRSL]) applied to cave sediments was published for the Gran Dolina and Galería sites. The authors proposed for Galería an age of 450 ka (thousands of years ago) for the units lower GIII and GII, suggesting that the human occupation there is younger than the hominid remains of Sima de los Huesos (>530 ka) around 1 km away. In this paper, we present new results obtained by combined Electron Spin Resonance/Uranium-series (ESR/U-series) dating on 20 herbivorous teeth from different levels at the Galería site. They are in agreement with the TL results for the upper part of the stratigraphic sequence (GIV and GIIIb), in the range of between 200 and 250 ka. But for the GIIIa to GIIb levels, the TL ages become abruptly older by 200 ka while ESR ages remain relatively constant. Finally, the TL and ESR data agree in the lowest part of the section (GIIa); both fall in the range of around 350-450 ka. Our results suggest a different interpretation for the GII, GIII and GIV units of Galería and the upper part of Gran Dolina (TD10 and TD11) than obtained by TL. The ESR/U-series results are supported by a Bayesian analysis, which allows a better integration between stratigraphic information and radiometric data. PMID:23830175

  14. Megalake Chad impact on climate and vegetation during the late Pliocene and the mid-Holocene

    C. Contoux


    Full Text Available Given the growing evidence for megalakes in the geological record, assessing their impact on climate and vegetation is important for the validation of palaeoclimate simulations and therefore the accuracy of model–data comparison in lacustrine environments. Megalake Chad (MLC occurrences are documented not only for the mid-Holocene but also for the Mio-Pliocene (Schuster et al., 2009. At this time, the surface covered by water would have reached up to ~350 000 km2 (Ghienne et al., 2002; Schuster et al., 2005; Leblanc et al., 2006, making it an important evaporation source, possibly modifying climate and vegetation in the Chad Basin. We investigated the impact of such a giant continental water area in two different climatic backgrounds within the Paleoclimate Model Intercomparison Project phase 3 (PMIP3: the late Pliocene (3.3 to 3 Ma, i.e. the mid-Piacenzian warm period and the mid-Holocene (6 kyr BP. In all simulations including MLC, precipitation is drastically reduced above the lake surface because deep convection is inhibited by overlying colder air. Meanwhile, convective activity is enhanced around MLC because of the wind increase generated by the flat surface of the megalake, transporting colder and moister air towards the eastern shore of the lake. The effect of MLC on precipitation and temperature is not sufficient to widely impact vegetation patterns. Nevertheless, tropical savanna is present in the Chad Basin in all climatic configurations, even without MLC presence, showing that the climate itself is the driver of favourable environments for sustainable hominid habitats.

  15. Metabolic correlates of hominid brain evolution.

    Leonard, William R; Robertson, Marcia L; Snodgrass, J Josh; Kuzawa, Christopher W


    Large brain sizes in humans have important metabolic consequences as humans expend a relatively larger proportion of their resting energy budget on brain metabolism than other primates or non-primate mammals. The high costs of large human brains are supported, in part, by diets that are relatively rich in energy and other nutrients. Among living primates, the relative proportion of metabolic energy allocated to the brain is positively correlated with dietary quality. Humans fall at the positive end of this relationship, having both a very high quality diet and a large brain size. Greater encephalization also appears to have consequences for aspects of body composition. Comparative primate data indicate that humans are 'under-muscled', having relatively lower levels of skeletal muscle than other primate species of similar size. Conversely, levels of body fatness are relatively high in humans, particularly in infancy. These greater levels of body fatness and reduced levels of muscle mass allow human infants to accommodate the growth of their large brains in two important ways: (1) by having a ready supply of stored energy to 'feed the brain', when intake is limited and (2) by reducing the total energy costs of the rest of the body. Paleontological evidence indicates that the rapid brain evolution observed with the emergence of Homo erectus at approximately 1.8 million years ago was likely associated with important changes in diet and body composition. PMID:14527625

  16. Relative femoral head size in early hominids.

    Corruccini, R S; McHenry, H M


    Relative growth of the human femur head is studied by a logarithmic principal components method. Growth rates differ according to the population sampled and the other body dimensions being compared, and especially according to sex. The results do not support biomechanical assumptions of strongly positive allometry of the femur head, which have been used to argue that the australopithecine hip joint was not relatively small. PMID:98052

  17. Paléocontraintes et déformations syn- et post-collision Afrique Europe identifiées dans la couverture mésozoïque et cénozoïque du Haut Atlas occidental (Maroc)Syn- and post-collision Africa Europe palaeostresses and deformations identified in the West High-Atlas Mesozoic and Cenozoic cover (Morocco)

    Amrhar, Mostafa

    Palaeostresses and deformation axis reconstruction related to the intracontinental High-Atlas uplift evidences two shortening phases from Upper Cretaceous to Quaternary. The first compression is oriented N20-30°E and is Maastrichtian to Oligocene age; the second one, oriented N120-160°E, is syn-Mio-Pliocene. Tectonic inversion of the lateral to compressive Jurassic regime is contemporaneous with the beginning of Africa and Europe collision. Rotation of the Mio-Pliocene shortening orientation could be linked to the change of the convergence direction between the Africa and Europe plates. To cite this article: M. Amrhar, C. R. Geoscience 334 (2002) 279-285.

  18. Messinian events in the Black Sea

    van Baak, Christiaan G C; Radionova, Eleanora P.; Golovina, Larisa A.; Raffi, Isabella; Kuiper, Klaudia F.; Vasiliev, Iuliana; Krijgsman, Wout


    Past hydrological interactions between the Mediterranean Sea and Black Sea are poorly resolved due to complications in establishing a high-resolution time frame for the Black Sea. We present a new greigite-based magnetostratigraphic age model for the Mio-Pliocene deposits of DSDP Hole 380/380A, dril

  19. Origin of hominids: European or African origin, neither or both?

    Senut, B.


    Full Text Available For the last twenty years, some scientists have suggested that the African ape and humans lineages emerged in Europe, a scenario known as the “Back to Africa Hypothesis”. Even though hominoids were widespread in Eurasia during the Middle and Upper Miocene due to the tropical conditions which prevailed in this region, we cannot dismiss the fact that they were present in Africa (contra some authors. Actually, they were highly diverse at that same time (at least 10 lineages represented even if the fossil record is less complete than in Eurasia. Postcranial elements from African species suggest that some features of modern hominoids were already present in the Lower and Middle Miocene of Africa and were not restricted to European ones. Considering the available evidence, it is not possible at this stage to favour a European origin over an African one. Hominoids were living in the tropical areas of Northern Africa and Southern Eurasia and faunal exchanges between the two continents occurred throughout the Middle and Upper Miocene, as the Tethys did not act as an effective barrier to interchanges between Europe and Asia.

    Durante los últimos veinte años, algunos científicos han sugerido que los grandes monos africanos y los linajes humanos surgieron en Europa, un escenario conocido como la “ Hipótesis de la vuelta a Africa”. A pesar de que los homínidos se extendieron en Eurasia durante el Mioceno Medio y Superior debido a las condiciones tropicales que prevalecian en esta region, no podemos descartar el hecho de que ellos estuvieron presentes en Africa (contra algunos autores. En realidad, ellos tuvieron una alta diversidad al mismo tiempo (al menos 10 líneas representadas, incluso si el registro fosil es menos completo que el de Eurasia. Elementos postcraneales de especies africanas sugieren que en algunos carácteres los homínidos modernos estaban ya presentes en el Mioceno Inferior y Medio de Africa, no sólo restringidos a las formas europeas. Teniendo en cuenta las evidencias disponibles, no es posible, en el estado actual de conocimiento, favorecer más un origen europeo que otro africano. Los homínidos vivieron en áreas tropicales del Norte de África y del Sur de Eurasia, cambios faunísticos se sucedieron entre los dos continents a lo largo del Mioceno Medio y Superior, sin que el Tetis actuase como una barrera efectiva a los intercambios entre Europa y Asia.

  20. A comparative morphometric study of the hominid lumbar spine.

    Martelli, S. A.


    This thesis investigates the size/shape variation in the lumbar spine of extant and fossil hominoids. As a novelty, 3D coordinate data sets were obtained from the last five consecutive presacral vertebrae for comparative analyses. Size/shape variation of single vertebrae and patterns of metameric size/shape variation along the lumbar spine are investigated. Large samples of populations of Homo sapiens, Gorilla gorilla, Pan troglodytes, and Pongo pygmaeus are investigated. The fossil sample in...

  1. Perikymata spacing and distribution on hominid anterior teeth.

    Dean, M C; Reid, D J


    We documented the spacing and distribution of perikymata on the buccal enamel surface of fossil hominin anterior teeth with reference to a sample of modern human and modern great ape teeth. A sample of 27 anterior teeth attributed to Australopithecus (5 to A. afarensis, 22 to A. africanus) and of 33 attributed to Paranthropus (6 to P. boisei, and 27 to P. robustus) were replicated and sputter-coated with gold to enable reflected light microscopy of their surface topography. Anterior teeth were then divided into 10 equal divisions of buccal crown height. The total perikymata count in each division of crown height was recorded using a binocular microscope fitted with a vernier micrometer eyepiece. Then the mean number of perikymata per millimeter was calculated for each division. Similar comparative data for a modern sample of 115 unworn human anterior teeth and 30 African great ape anterior teeth were collected from ground sections. Perikymata counts in each taxon (together with either known or presumed periodicities of perikymata) were then used to estimate enamel formation times in each division of crown height, for all anterior tooth types combined. The distributions of these estimates of time taken to form each division of crown height follow the same trends as the actual perikymata counts and differ between taxa in the same basic way. The distinction between modern African great apes and fossil hominins is particularly clear. Finally, we calculated crown formation times for each anterior tooth type by summing cuspal and lateral enamel formation times. Estimates of average crown formation times in australopiths are shorter than those calculated for both modern human and African great ape anterior teeth. The data presented here provide a better basis for exploring differences in perikymata spacing and distribution among fossil hominins, and provide the first opportunity to describe four specimens attributed to Homo in this context. Preliminary data indicate that differences may exist among the species attributed to early Homo, especially between Homo ergaster and Homo rudolfensis on the one hand, and Homo habilis sensu strico on the other. PMID:11596000

  2. Evolutionary relationships of wild hominids recapitulated by gut microbial communities.

    Howard Ochman

    Full Text Available Multiple factors over the lifetime of an individual, including diet, geography, and physiologic state, will influence the microbial communities within the primate gut. To determine the source of variation in the composition of the microbiota within and among species, we investigated the distal gut microbial communities harbored by great apes, as present in fecal samples recovered within their native ranges. We found that the branching order of host-species phylogenies based on the composition of these microbial communities is completely congruent with the known relationships of the hosts. Although the gut is initially and continuously seeded by bacteria that are acquired from external sources, we establish that over evolutionary timescales, the composition of the gut microbiota among great ape species is phylogenetically conserved and has diverged in a manner consistent with vertical inheritance.

  3. Evidence of termite foraging by Swartkrans early hominids

    Backwell, Lucinda R.; d'Errico, Francesco


    Previous studies have suggested that modified bones from the Lower Paleolithic sites of Swartkrans and Sterkfontein in South Africa represent the oldest known bone tools and that they were used by Australopithecus robustus to dig up tubers. Macroscopic and microscopic analysis of the wear patterns on the purported bone tools, pseudo bone tools produced naturally by known taphonomic processes, and experimentally used bone tools confirm the anthropic origin of the mo...

  4. Explaining the imperfection of the molecular clock of hominid mitochondria.

    Eva-Liis Loogväli

    Full Text Available The molecular clock of mitochondrial DNA has been extensively used to date various genetic events. However, its substitution rate among humans appears to be higher than rates inferred from human-chimpanzee comparisons, limiting the potential of interspecies clock calibrations for intraspecific dating. It is not well understood how and why the substitution rate accelerates. We have analyzed a phylogenetic tree of 3057 publicly available human mitochondrial DNA coding region sequences for changes in the ratios of mutations belonging to different functional classes. The proportion of non-synonymous and RNA genes substitutions has reduced over hundreds of thousands of years. The highest mutation ratios corresponding to fast acceleration in the apparent substitution rate of the coding sequence have occurred after the end of the Last Ice Age. We recalibrate the molecular clock of human mtDNA as 7990 years per synonymous mutation over the mitochondrial genome. However, the distribution of substitutions at synonymous sites in human data significantly departs from a model assuming a single rate parameter and implies at least 3 different subclasses of sites. Neutral model with 3 synonymous substitution rates can explain most, if not all, of the apparent molecular clock difference between the intra- and interspecies levels. Our findings imply the sluggishness of purifying selection in removing the slightly deleterious mutations from the human as well as the Neandertal and chimpanzee populations. However, for humans, the weakness of purifying selection has been further exacerbated by the population expansions associated with the out-of Africa migration and the end of the Last Ice Age.

  5. Enamel hypoplasia in a pliocene hominid from Chad.

    Brunet, Michel; Fronty, Pierre; Sapanet, Michel; de Bonis, Louis; Viriot, Laurent


    Abel is the first Australopithecine known west of the East African Rift Valley. The fossil finds include a perisymphyseal fragment of an adult mandible with well-preserved crowns of the right I2-P4 and the left C-P4. Abel's dentition displays many enamel defects, which are described in detail for each tooth. Pitting affected every tooth, while larger, shallow depressions were observed on the canines alone. From two to four pit bands occurred on the different teeth, each resulting from a separate hypoplastic episode. In modern humans, a large number of causes, both environmental and genetic, have been suggested for such enamel defects. It seems probable that Abel's pathology was systemic. However, the occurrence of a number of bands and the variable intensity of the attacks make it difficult to say whether there was a single, repetitive cause or different etiologies. Possible causes discussed here include recurrent fevers and seasonal nutritional deficiencies. PMID:12489142

  6. Becoming a hominid: Notes on the early taxonomy of Australopithecus

    Štrkalj, Goran


    The paper attempts to trace the first suggestions that the Australopithecus as a member of the family Hominidae is to be found in the works of the German anthropologist Paul Adloff and the American scientist Dudley J. Morton. Adloff's and especially Morton's views, although largely neglected at the time when they were first articulated, represent the first steps towards the modern position on the taxonomy of Australopithecus.

  7. Insights into hominid evolution from the gorilla genome sequence.

    Scally, Aylwyn; Dutheil, Julien Y; Hillier, LaDeana W; Jordan, Gregory E; Goodhead, Ian; Herrero, Javier; Hobolth, Asger; Lappalainen, Tuuli; Mailund, Thomas; Marques-Bonet, Tomas; McCarthy, Shane; Montgomery, Stephen H; Schwalie, Petra C; Tang, Y Amy; Ward, Michelle C; Xue, Yali; Yngvadottir, Bryndis; Alkan, Can; Andersen, Lars N; Ayub, Qasim; Ball, Edward V; Beal, Kathryn; Bradley, Brenda J; Chen, Yuan; Clee, Chris M; Fitzgerald, Stephen; Graves, Tina A; Gu, Yong; Heath, Paul; Heger, Andreas; Karakoc, Emre; Kolb-Kokocinski, Anja; Laird, Gavin K; Lunter, Gerton; Meader, Stephen; Mort, Matthew; Mullikin, James C; Munch, Kasper; O'Connor, Timothy D; Phillips, Andrew D; Prado-Martinez, Javier; Rogers, Anthony S; Sajjadian, Saba; Schmidt, Dominic; Shaw, Katy; Simpson, Jared T; Stenson, Peter D; Turner, Daniel J; Vigilant, Linda; Vilella, Albert J; Whitener, Weldon; Zhu, Baoli; Cooper, David N; de Jong, Pieter; Dermitzakis, Emmanouil T; Eichler, Evan E; Flicek, Paul; Goldman, Nick; Mundy, Nicholas I; Ning, Zemin; Odom, Duncan T; Ponting, Chris P; Quail, Michael A; Ryder, Oliver A; Searle, Stephen M; Warren, Wesley C; Wilson, Richard K; Schierup, Mikkel H; Rogers, Jane; Tyler-Smith, Chris; Durbin, Richard


    Gorillas are humans' closest living relatives after chimpanzees, and are of comparable importance for the study of human origins and evolution. Here we present the assembly and analysis of a genome sequence for the western lowland gorilla, and compare the whole genomes of all extant great ape genera. We propose a synthesis of genetic and fossil evidence consistent with placing the human-chimpanzee and human-chimpanzee-gorilla speciation events at approximately 6 and 10 million years ago. In 30% of the genome, gorilla is closer to human or chimpanzee than the latter are to each other; this is rarer around coding genes, indicating pervasive selection throughout great ape evolution, and has functional consequences in gene expression. A comparison of protein coding genes reveals approximately 500 genes showing accelerated evolution on each of the gorilla, human and chimpanzee lineages, and evidence for parallel acceleration, particularly of genes involved in hearing. We also compare the western and eastern gorilla species, estimating an average sequence divergence time 1.75 million years ago, but with evidence for more recent genetic exchange and a population bottleneck in the eastern species. The use of the genome sequence in these and future analyses will promote a deeper understanding of great ape biology and evolution. PMID:22398555

  8. Some observations on surface instability associated with coal deposits in South Sumatra

    Walton, G.; Gunawan, R.


    Recent exploration of Indonesian government concessions in South Sumatra by Shell Mijnbouw N.V. has revealed small-scale surface instability of recent origin, which could be important with respect to the construction of large spoil dumps. The area is SW of Palembang where Mio-Pliocene coals of the Muara Enim formation outcrop in country around Tanjung Enim. Preliminary sampling of three coal seams was made in a series of trenches along the valley of the Air Muara Tiga.

  9. Polygenetic development and paleoenvironmental implications of a Pleistocene calcrete at Tongoy, central northern Chile.

    M. Pfeiffer; J. Le Roux; H. Kemnitz


    The Norte Chico Region, in central northern Chile, is a particularly sensitive area to Quaternary climate changes because of its extreme climatic gradients. However, very little has been done to determine the late Pleistocene climatic conditions of the area. Calcretes are known to be important repositories of information on past ecosystems and environments. In the Tongoy paleobay, a series of four marine beach terraces have developed over a Mio-Pliocene calcareous formation since MIS 11 to th...

  10. Evolution of Lake Chad Basin hydrology during the mid-Holocene: A preliminary approach from lake to climate modelling

    Sepulchre, Pierre; Schuster, Mathieu; Ramstein, Gilles; Krinnezr, Gerhard; Girard, Jean-Francois; Vignaud, Patrick; Brunet, Michel


    During the mid-Holocene (6000 yr Before Present, hereafter yr BP) the Chad Basin was occupied by a large endoreic lake, called Lake Mega-Chad. The existence of this lake at that time seems linked to increased monsoonal moisture supply to the Sahel and the Sahara, which in turn was probably ultimately caused by variations in the orbital forcing and higher temperature gradients between ocean and continent. This study provides a synthesis of several works carried out on the Lake Chad Basin and analyses the results of a simulation of the mid-Holocene climate with an Atmosphere General Circulation Model (LMDZ for Laboratoire de Météorologie Dynamique, IPSL Paris), with emphasis on the possible conditions leading to the existence of Lake Mega-Chad. The aim is to define the best diagnostics to understand which mechanisms lead to the existence of the large lake. This paper is the first step of an ongoing work that intends to understand the environmental conditions that this part of Africa experienced during the Upper Miocene (ca. 7 Ma BP), an epoch that was contemporaneous with the first known hominids. Indeed, early hominids of Lake Chad Basin, Australopithecus bahrelghazali [ Brunet, M., et al., 1995. The first australopithecine 2500 kilometers west of the Rift-Valley (Chad). Nature, 378(6554): 273-275] and Sahelanthropus tchadensis [Brunet, M., et al., 2002. A new hominid from the Upper Miocene of Chad, central Africa. Nature, 418(6894): 145-151; Brunet, M., et al., 2005. New material of the earliest hominid from the Upper Miocene of Chad. Nature, 434(7034): 752-755] are systematically associated with wet episodes that are documented for 7 Ma BP [Vignaud, P., et al., 2002. Geology and palaeontology of the Upper Miocene Toros-Menalla hominid locality, Chad. Nature, 418(6894): 152-155] and testified by extended lacustrine deposits (diatomites, pelites, various aquatic fauna). Because the mid-Holocene was the last such mega-lake episode, our aim here is to assess the

  11. Nature of the upper mantle and metasomatic processes on either side of the Sillon Houiller (French Massif Central)

    Peridotite xenoliths collected in two Mio-Pliocene volcanoes on either side of the Sillon Houiller (French Massif Central) have contrasting characteristics. East of the Sillon Houiller, the peridotites record anomalously high temperatures (1,250 deg. C) and extensive re-equilibration with basaltic melts. To the waste, equilibrium temperatures are much lower (950 deg C) and the peridotites bear evidence for interaction with volatile-rich small melt fractions. In agreement with seismic tomographic data, these results indicate that the Massif Central lithospheric mantle is strongly affected by mantle plume upwelling to the east of the Sillon Houiller, while this effect is moderate to the west. (authors)

  12. Probing atomic scale transformation of fossil dental enamel using Fourier transform infrared and nuclear magnetic resonance spectroscopy : a case study from the Tugen Hills (Rift Gregory, Kenya)

    Yi, H. H.; Balan, Etienne; Gervais, C; SEGALEN, L.; Roche, D; PERSON, A.; Fayon, F.; Morin, G.; F. Babonneau


    A series of fossil tooth enamel samples was investigated by Fourier transform infrared (FTIR) spectroscopy, C-13 and F-19 magic-angle spinning nuclear magnetic resonance (MAS NMR) and scanning electron microscopy (SEM). Tooth remains were collected in Mio-Pliocene deposits of the Tugen Hills in Kenya. Significant transformations were observed in fossil enamel as a function of increasing fluorine content (up to 2.8 wt.%). FTIR spectroscopy revealed a shift of the nu(1) PO4 stretching band to h...

  13. Depósitos epitermales de baja sulfuración ricos en sulfuros de metales base, distrito aurífero La Carolina, San Luis, Argentina

    Gallard-Esquivel María Cecilia; Urbina, Nilda Esther; Sruoga, Patricia; Japas, María Silvia


    Low-sulfidation epithermal base-metal sulfide-rich deposits, La Carolina gold-bearing district,San Luis, Argentina. La Carolina gold-bearing district is located at the western end of the Metallogenetic Belt of San Luis, which is spatially and genetically related to the mesosilicic volcanism of mio-pliocene age. The volcanic arc experienced an eastward migration, due to the flattening of the Nazca plate in the segment 27°-33°S, known as the Pampean flat-slab. At La Carolina, the volcanic activ...

  14. Early hominin speciation at the Plio/Pleistocene transition.

    Cameron, D W


    Over the last half-decade or so, there has been an explosion in the recognition of hominin genera and species. We now have the late Miocene genera Orrorin and Sahelanthropus, the mid Pliocene genus Kenyanthropus, three new Pliocene species of Australopithecus (A. anamensis, A. garhi and A. bahrelghazali) and a sub species of Ardipithecus (Ar. r. kadabba) to contend with. Excepting also the more traditional species allocated to Paranthropus, Australopithecus and early Homo we are approaching around 15 species over 5 million years (excluding hominin evolution over the last one million years). Can such a large number of hominin species be justified? An examination of extant hominid (Gorilla gorilla, Pan troglodytes, and Pan paniscus) anatomical variability indicates that the range of fossil hominin variability supports the recognition of this large number of fossil species. It is also shown that not all hominins are directly related to the emergence of early Homo and as such have become extinct. Indeed the traditional australopithecine species 'A'. anamensis, 'A'. afarensis and 'A'. garhi are considered here to belong to a distinct genus Praeanthropus. They are also argued not be hominins, but rather an as yet undefined hominid group from which the more derived hominins evolved. The first hominin is represented by A. africanus or a hominin very much like it. The Paranthropus clade is defined by a derived heterochronic condition of peramorphosis, associated with sequential progenesis (contraction of successive growth stages) in brain and dental development, but a mixture of peramorphic and paedomorphic features in its craniofacial anatomy. Conversely, Kenyanthropus and Homo both share a pattern of peramorphosis, associated with sequential hypermorphosis (prolongation of successive growth stages) in brain development, and paedomorphosis processes in cranial, facial and dental development. This suggests, that these two clades share an important synapomorphy not

  15. Functional and phylogenetic analyses of chromosome 21 promoters and hominid-specific transcription factor binding sites

    Querfurth, Robert


    The focus of this work addresses functional studies of human and primate promoters, and the genome-wide localization and validation of human-specific transcription factor binding sites of the essential transcription factor GABPa. In this context, the development of an improved PCR protocol, including the careful adjustment of PCR additives to compose an efficient enhancer mix, was central to the amplification of large GC-rich promoter fragments used as source for the functional studies. Based...

  16. Evidence for the unique function of DHA during the evolution of the modern hominid brain

    Crawford M.A.


    Full Text Available The African savanna ecosystem of the large mammals and primates was associated with a dramatic decline in relative brain capacity. This reduction happened to be associated with a decline in docosahexaenoic acid (DHA from the food chain. DHA is required for brain structures and growth. The biochemistry implies that the expansion of the human brain required a plentiful source of preformed DHA. The richest source of DHA is the marine food chain while the savannah environment offers very little of it. Consequently H. sapiens could not have evolved on the savannahs. Recent fossil evidence indicates that the lacustrine and marine food chain was being extensively exploited at the time cerebral expansion took place and suggests the alternative that the transition from the archaic to modern humans took place at the land\\\\water interface. Contemporary data on tropical lake shore dwellers reaffirms the above view. Lacustrine habitats provide nutritional support for the vascular system, the development of which would have been a prerequisite for cerebral expansion. Both arachidonic acid (AA and DHA would have been freely available from such habitats providing the double stimulus of preformed acyl components for the developing blood vessels and brain. The w3 docosapentaenoic acid precursor (w3DPA was the major w3 metabolite in the savanna mammals. Despite this abundance, neither it or the corresponding w6DPA were used for the photoreceptor nor the synapse. A substantial difference between DHA and other fatty acids is required to explain this high specificity. Studies on fluidity and other mechanical features of cell membranes have not revealed a difference of such magnitude between even a-linolenic acid (LNA and DHA sufficient to explain the exclusive use of DHA. We suggest that the evolution of the large human brain depended on a rich source of DHA from the land\\\\water interface. We review a number of proposals for the possible influence of DHA on physical properties of the brain that are essential for its function.

  17. A hominid from the lower Pleistocene of Atapuerca, Spain: possible ancestor to Neandertals and modern humans.

    Bermúdez de Castro, J M; Arsuaga, J L; Carbonell, E; Rosas, A; Martínez, I; Mosquera, M


    Human fossil remains recovered from the TD6 level (Aurora stratum) of the lower Pleistocene cave site of Gran Dolina, Sierra de Atapuerca, Spain, exhibit a unique combination of cranial, mandibular, and dental traits and are suggested as a new species of Homo-H. antecessor sp. nov. The fully modern midfacial morphology of the fossils antedates other evidence of this feature by about 650, 000 years. The midfacial and subnasal morphology of modern humans may be a retention of a juvenile pattern that was not yet present in H. ergaster. Homo antecessor may represent the last common ancestor for Neandertals and modern humans. PMID:9162001

  18. : Quantification of the morphological evolution of the Hominid skull and heterochronies

    Chaline, Jean; DAVID, Bruno; Magniez-Jannin, Françoise; Dambricourt Malassé, Anne; Marchand, Didier; Courant, Frédéric; Millet, Jean-Jacques


    Les comparaisons réalisées entre des crânes d'individus adultes de diverses espèces de singes supérieurs, d'hommes fossiles et modernes dans les plans sagittal, Francfort et orthosagittal, révèlent la succession de trois plans d'organisation distincts ; - Singe supérieur », « Australopithèque », et « Homo ». renfermant les hommes archaïques {Homo ergaster - erectus - neandertalensis) et les hommes modernes (Homo sapiens). Les changements morphologiques entre ces plans sont quantifiés pour la ...

  19. A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania

    Brochu, Christopher A.; Njau, Jackson; Blumenschine, Robert J.; Densmore, Llewellyn D


    Background The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular “horns” over the ears and a relatively deep snout, these resemb...

  20. Y-Chromosome Variation in Hominids: Intraspecific Variation Is Limited to the Polygamous Chimpanzee

    Gabriele Greve; Evguenia Alechine; Pasantes, Juan J.; Christine Hodler; Wolfram Rietschel; Robinson, Terence J.; Werner Schempp


    BACKGROUND: We have previously demonstrated that the Y-specific ampliconic fertility genes DAZ (deleted in azoospermia) and CDY (chromodomain protein Y) varied with respect to copy number and position among chimpanzees (Pan troglodytes). In comparison, seven Y-chromosomal lineages of the bonobo (Pan paniscus), the chimpanzee's closest living relative, showed no variation. We extend our earlier comparative investigation to include an analysis of the intraspecific variation of these genes in go...

  1. Y-Chromosome variation in hominids: intraspecific variation is limited to the polygamous chimpanzee.

    Gabriele Greve

    Full Text Available BACKGROUND: We have previously demonstrated that the Y-specific ampliconic fertility genes DAZ (deleted in azoospermia and CDY (chromodomain protein Y varied with respect to copy number and position among chimpanzees (Pan troglodytes. In comparison, seven Y-chromosomal lineages of the bonobo (Pan paniscus, the chimpanzee's closest living relative, showed no variation. We extend our earlier comparative investigation to include an analysis of the intraspecific variation of these genes in gorillas (Gorilla gorilla and orangutans (Pongo pygmaeus, and examine the resulting patterns in the light of the species' markedly different social and mating behaviors. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence in situ hybridization analysis (FISH of DAZ and CDY in 12 Y-chromosomal lineages of western lowland gorilla (G. gorilla gorilla and a single lineage of the eastern lowland gorilla (G. beringei graueri showed no variation among lineages. Similar findings were noted for the 10 Y-chromosomal lineages examined in the Bornean orangutan (Pongo pygmaeus, and 11 Y-chromosomal lineages of the Sumatran orangutan (P. abelii. We validated the contrasting DAZ and CDY patterns using quantitative real-time polymerase chain reaction (qPCR in chimpanzee and bonobo. CONCLUSION/SIGNIFICANCE: High intraspecific variation in copy number and position of the DAZ and CDY genes is seen only in the chimpanzee. We hypothesize that this is best explained by sperm competition that results in the variant DAZ and CDY haplotypes detected in this species. In contrast, bonobos, gorillas and orangutans-species that are not subject to sperm competition-showed no intraspecific variation in DAZ and CDY suggesting that monoandry in gorillas, and preferential female mate choice in bonobos and orangutans, probably permitted the fixation of a single Y variant in each taxon. These data support the notion that the evolutionary history of a primate Y chromosome is not simply encrypted in its DNA sequences, but is also shaped by the social and behavioral circumstances under which the specific species has evolved.

  2. Development of the palatal size in Pan troglodytes, Hominids and Homo sapiens.

    Arnold, W H; Zoellner, A; Sebastian, T


    As the hard palate plays an important role in speech production it was the aim of this study whether similarities or dissimilarities in palatal size may allow conclusions about the ability to produce speech in the extant investigated species. The palatal size of Pan troglodytes, Homo sapiens, Australopithecus afarensis, Australopithecus africanus, Australopithecus robustus, Australopithecus boisei, Homo erectus, Homo neanderthalensis and Cro-Magnon has been investigated using euclidian distance matrix analysis (EDMA) and thin-plate-spline analysis. The results show that the palatal size of all australopithecine specimens and H. erectus is very similar to that of P toglodytes, whereas the palatal size of H. neanderthalensis more closely resembles that of H. sapiens. Postnatal development of palatal size in P troglodytes is different from that of H. sapiens. In P troglodytes not only the size of the palate changes but also the form. In H. sapiens there is little change in form, but a continuos uniform growth from infantile to adult specimens. From the results we conclude that in all australopithecine samples which have been investigated, the palatal size is similar to that of P troglodytes. Therefore, it is unlikely that austraopithecine individuals were capable of producing vowels and consonants. The palatal size of H. neandethalensis and Cro-Magnon is similar to that of H. sapiens which may indicate the possibility that they were capable of speech production. PMID:15646285

  3. Clustered mutations in hominid genome evolution are consistent with APOBEC3G enzymatic activity

    Pinto, Yishay; Gabay, Orshay; Arbiza, Leonardo; Sams, Aaron J.; Keinan, Alon; Levanon, Erez Y.


    The gradual accumulation of mutations by any of a number of mutational processes is a major driving force of divergence and evolution. Here, we investigate a potentially novel mutational process that is based on the activity of members of the AID/APOBEC family of deaminases. This gene family has been recently shown to introduce—in multiple types of cancer—enzyme-induced clusters of co-occurring somatic mutations caused by cytosine deamination. Going beyond somatic mutations, we hypothesized t...

  4. A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania

    Brochu, Christopher A.; Jackson Njau; Robert J Blumenschine; Densmore, Llewellyn D


    BACKGROUND: The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular "horns" over the ears and a relatively deep snout, these resem...

  5. Y-Chromosome Variation in Hominids: Intraspecific Variation Is Limited to the Polygamous Chimpanzee

    Greve, Gabriele; Alechine, Evguenia; Pasantes, Juan J.; Hodler, Christine; Rietschel, Wolfram; Robinson, Terence J; Schempp, Werner


    Background We have previously demonstrated that the Y-specific ampliconic fertility genes DAZ (deleted in azoospermia) and CDY (chromodomain protein Y) varied with respect to copy number and position among chimpanzees (Pan troglodytes). In comparison, seven Y-chromosomal lineages of the bonobo (Pan paniscus), the chimpanzee's closest living relative, showed no variation. We extend our earlier comparative investigation to include an analysis of the intraspecific variation of these genes in gor...

  6. Bone strength and athletic ability in hominids: Ardipithecus ramidus to Homo sapiens

    Lee, S. A.


    The ability of the femur to resist bending stresses is determined by its midlength cross-sectional geometry, its length and the elastic properties of the mineral part of the bone. The animal's athletic ability, determined by a ``bone strength index,'' is limited by this femoral bending strength in relation to the loads on the femur. This analysis is applied to the fossil record for Homo sapiens, Homo neanderthalensis, Homo erectus, Homo habilis, Australopithecus afarensis and Ardipithecus ramidus. Evidence that the femoral bone strength index of modern Homo sapiens has weakened over the last 50,000 years is found.

  7. Metamorphic zoning and geodynamic evolution of an inverted crustal section (Karakorum margin, N Pakistan), evidence for two metamorphic events

    Rolland, Y.; Carrio-Schaffhauser, E.; Sheppard, S. M. F.; Pêcher, A.; Esclauze, L.


    The Karakorum Range comprises a crustal section of marbles and metapelites providing an opportunity to study the extent of high-temperature metamorphic reequilibration in an active orogen. Metamorphism culminated during the Mio-Pliocene, at 6 7 Ma. Peak metamorphic conditions increased from south to north, i.e. from (1) the Upper Anchizone grade (lawsonite, chlorite smectite) to (2) lower granulite migmatite grade (HT˜800°C) conditions along strike of a 30-km section perpendicular to the structural fabric of the rocks. The metamorphic section can be separated into two domains: 1. A domain with low to transitional metamorphic conditions, with respect to the HT zone, where initial bedding is preserved. These moderate PT conditions prevailed during the main tectonic stacking event (50 37 Ma), prior to the Mio-Pliocene event. In this domain, metamorphism is governed by fluid-assisted grain-scale diffusion, as suggested by the progressive coarsening of minerals with increasing metamorphic grade and the preservation of sedimentary δ13C signatures in carbonates. A low thermal gradient (17°C/km) is derived from P-T estimates of the prograde metamorphic sequences.

  8. A fossil aardvark (Mammalia, Tubulidentata) from the lower Pliocene of Chad

    Lehmann, Thomas; Vignaud, Patrick; Mackaye, Hassane Taïsso; Brunet, Michel


    The Mission Paléoanthropologique Franco-Tchadienne (MPFT) found a new species of Orycteropodidae (Mammalia, Tubulidentata) in the Kollé fossiliferous sector, northern Chad. After Orycteropus abundulafus [Journal of Vertebrate Paleontology 20 (1) (2000) 205-209; Lehmann, T., Vignaud, P., Likius A., Brunet M., in press. A new Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of Northern Chad. Zool. J. Linnean Soc.], this specimen is the second complete skeleton of fossil aardvark found in the Djurab desert. It is the first complete representative of an Orycteropus species found in the Pliocene of Africa. In regard to the Miocene fossil aardvarks, this new taxon, Orycteropus djourabensis nov. sp., shows more affinities with the extant O. afer. The main differences are the larger teeth and the shorter hand in the fossil form. Kossom Bougoudi and Kollé represent a chronological series that gives a unique opportunity for studying the evolution of the African Tubulidentata around the Mio-Pliocene boundary (5.5-4 My). The new species is distinct from the older Chadian Orycteropodid from KB and it embodies the taxonomic turnover that took place within the order Tubulidentata around this boundary in Africa. Moreover, this new species is the oldest known Orycteropus species that clearly belongs to the modern forms including the extant aardvark.

  9. Genomic differentiation of Neanderthals and anatomically modern man allows a fossil-DNA-based classification of morphologically indistinguishable hominid bones.

    Scholz, M.; Bachmann, L; Nicholson, G J; Bachmann, J.; Giddings, I; Rüschoff-Thale, B; Czarnetzki, A; Pusch, C. M.


    Southern blot hybridizations of genomic DNA were introduced as a relatively simple fossil-DNA-based approach to classify remains of Neanderthals. When hybridized with genomic DNA of either human or Neanderthal origin, DNA extracted from two Neanderthal finds-the Os parietale, from Warendorf-Neuwarendorf, Germany, and a clavicula, from Krapina, Croatia-was shown to yield hybridization signals that differ by at least a factor of two compared to the signals obtained with the use of fossil DNA of...

  10. Analysis of sedimentary-geomorphologic variation and the living environment of hominids at the Shuidonggou Paleolithic site

    GAO Xing; YUAN BaoYin; PEI ShuWen; WANG HuiMin; CHEN FuYou; FENG XingWu


    Shuidonggou is one of the most important Upper Paleolithic sites in North China. Due to the presence of rich human remains, animal fossils, abundant sporopolien and unique geological sequence, it is the type site for Late Pleistocene to Holocene human occupation and environmental change in the Ningxia-lnner Mongolia region. Many scholars suggest that the site should be named the "Shuidong- gou Formation" of Late Pleistocene in North China. Dating results indicate that ancient human activities at the site took place 30-24 ka (Marine Isotope Stage [MIS] 3). The climate at that time was warmer and moister than present day, and adequate precipitation led to the formation of water pack depressions where broad-leaf trees and sparse forest vegetations, as well as herbivorous animals flourished, mak-ing the area suitable for early human hunting, gathering and survival. The Neolithic human occupation happened 9-5 ka at the site, while similar environmental conditions with MIS3 occurred. The absence of human activity record in the region during the Last Glacial Maximum (MIS2) suggests that the envi-ronment was too harsh for humans to live there.

  11. On Paleobiogeography of Italian Tertiary Mammals / Elementi di Paleobiogeografia dei mammiferi terziari dell'Italia

    Tassos Kotsakis


    Full Text Available Abstract In this paper the Italian continental Tertiary mammalofaunas are examined. For each known layer the faunal composition, the age and the center of spreading of each component are pointed out. Besides some isolated remains collected in marine sediments, faunistic assemblages coming from three Eocene, six Oligocene, six Miocene, three Mio/Pliocene, six Lower Pliocene, more than ten Upper Pliocene and two Pleistocene sites interesting for mammalian Tertiary biogeography are analysed. Riassunto Vengono esaminate le faune a mammiferi continentali del Terziario italiano. Per ogni giacimento viene indicata la composizione della fauna, l'età e l'area di provenienza delle varie componenti. A prescindere dai resti isolati raccolti in sedimenti marini, vengono analizzate le faune di trentasei località (tre eoceniche, sei oligoceniche, sei mioceniche, tre mio/plioceniche, sei plioceniche inferiori, dieci plioceniche superiori e due pleistoceniche che presentino interesse per la biogeografia del Terziario.

  12. Geology and preliminary dating of the hominid-bearing sedimentary fill of the Sima de los Huesos Chamber, Cueva Mayor of the Sierra de Atapuerca, Burgos, Spain.

    Bischoff, J L; Fitzpatrick, J A; León, L; Arsuagà, J L; Falgueres, C; Bahain, J J; Bullen, T


    Sediments of the Sima de los Huesos vary greatly over distances of a few meters. This is typical of interior cave facies, and caused by cycles of cut and fill. Mud breccias containing human bones, grading upwards to mud containing bear bones, fill an irregular surface cut into basal marks and sands. The lack of Bedding and the chaotic abundance of fragile speleothem clasts in the fossiliferous muds suggests that the deposit was originally a subterranean pond facies, and that after emplacement of the human remains, underwent vigorous post-depositional rotation and collapse and brecciation, caused by underlying bedrock dissolution and undermining. The fossiliferous deposits are capped by flowstone and guano-bearing muds which lack large-mammal fossils. U-series and radiocarbon dating indicates the capping flowstones formed from about 68 ka to about 25 ka. U-series analyses of speleothem clasts among the human fossils indicate that all are at, or close to, isotopic equilibrium (> 350 ka). The distribution of U-series dates for 25 bear bones (154 +/- 66 ka) and for 16 human bones (148 +/- 34 ka) is similar and rather broad. Because the human bones seem to be stratigraphically older than chose of the bears, the results would indicate that most of the bones have been accumulating uranium irregularly with time. Electron spin resonance (ESR) analyses of six selected bear bones indicates dates of 189 +/- 28 ka, for which each is cordant with their corresponding U-series date (181 +/- 41 ka). Combined ESR and U-series dates for these samples yielded 200 +/- 4 ka. Such agreement is highly suggestive that uranium uptake in these bones was close to the early-uptake (EU) model, and the dates are essentially correct. Another three selected samples yielded combined ESR U-series dates of 320 +/- 4 ka with a modeled intermediate-mode of uranium uptake. The dating results, therefore, seem to provide a firm minimum age of about 200 ka for the human entry: and suggestive evidence of entry before 320 ka. PMID:9300339

  13. Le comportement alimentaire des primates : de la socio-écologie régime éclectique des hominidés

    Hladik, Claude Marcel


    Theories about hominization, taking into consideration dietary adaptations and brain size increase, are discussed after a review of major data on primate feeding behavior, including a summary of the author's papers. Field work on primate published since the seventies shows a persistence of ancient morphological, physiological and behavioral adaptations in the present food responses. For instance, distribution of insects determines the size of individual territories of prosimians; however the ...

  14. The role of docosahexaenoic and the marine food web as determinants of evolution and hominid brain development: the challenge for human sustainability.

    Crawford, Michael A; Broadhurst, C Leigh


    Life originated on this planet about 3 billion years ago. For the first 2.5 billion years of life there was ample opportunity for DNA modification. Yet there is no evidence of significant change in life forms during that time. It was not until about 600 million years ago, when the oxygen tension rose to a point where air-breathing life forms became thermodynamically possible, that a major change can be abruptly seen in the fossil record. The sudden appearance of the 32 phyla in the Cambrian fossil record was also associated with the appearance of intracellular detail not seen in previous life forms. That detail was provided by cell membranes made with lipids (membrane fats) as structural essentials. Lipids thus played a major, as yet unrecognised, role as determinants in evolution. The compartmentalisation of intracellular, specialist functions as in the nucleus, mitochondria, reticulo-endothelial system and plasma membrane led to cellular specialisation and then speciation. Thus, not only oxygen but also the marine lipids were drivers in the Cambrian explosion. Docosahexaenoic acid (DHA) (all-cis-docosa-4,7,10,13,16,19-hexaenoic acid, C22:6ω3 or C22:6, n-3, DHA) is a major feature of marine lipids. It requires six oxygen atoms to insert its six double bonds, so it would not have been abundant before oxidative metabolism became plentiful. DHA provided the membrane backbone for the emergence of new photoreceptors that converted photons into electricity, laying the foundation for the evolution of other signalling systems, the nervous system and the brain. Hence, the ω3 DHA from the marine food web must have played a critical role in human evolution. There is also clear evidence from molecular biology that DHA is a determinant of neuronal migration, neurogenesis and the expression of several genes involved in brain growth and function. That same process was essential to the ultimate cerebral expansion in human evolution. There is now incontrovertible support of this hypothesis from fossil evidence of human evolution taking advantage of the marine food web. Lipids are still modifying the present evolutionary phase of our species; their signature is evident in the changing panorama of non-communicable diseases. The most worrying change in disease pattern is the sharp rise in brain disorders, which, in the European Union, has overtaken the cost of all other burdens of ill health at €386 billion for the 25 member states at 2004 prices. In 2007, the UK cost was estimated at £77 billion and confirmed in 2010 at £105 billion - greater than heart disease and cancer combined. The rise in mental ill health is now being globalised. The solution to the rising vascular disorders in the last century and now brain disorders in this century lies in a radical reappraisal of the food system, which last century was focussed on protein and calories, with little attention paid to the requirements of the brain - the very organ that was the determinant of human evolution. With the marine fish catch having plateaued 20 years ago and its sustainability now under threat, a critical aspect of this revision is the development of marine agriculture from estuarine, coastal and oceanic resources. Such action is likely to play a key role in future health and intelligence. PMID:22544773

  15. Sociální rozumění u lidí a ostatních hominidů

    Urban, Petr


    Roč. 69, č. 7 (2014), s. 591-603. ISSN 0046-385X R&D Projects: GA ČR GPP401/12/P544 Institutional support: RVO:67985955 Keywords : Social cognition * Anthropological difference * Theory of mind * Interactive turn * Joint attention * Joint intentionality * Apes Subject RIV: AA - Philosophy ; Religion

  16. Surface uplift and convective rainfall along the southern Central Andes (Angastaco Basin, NW Argentina)

    Pingel, Heiko; Mulch, Andreas; Alonso, Ricardo N.; Cottle, John; Hynek, Scott A.; Poletti, Jacob; Rohrmann, Alexander; Schmitt, Axel K.; Stockli, Daniel F.; Strecker, Manfred R.


    Stable-isotopic and sedimentary records from the orogenic Puna Plateau of NW Argentina and adjacent intermontane basins to the east furnish a unique late Cenozoic record of range uplift and ensuing paleoenvironmental change in the south-central Andes. Today, focused precipitation in this region occurs along the eastern, windward flanks of the Eastern Cordillera and Sierras Pampeanas ranges, while the orogen interior constitutes high-elevation regions with increasingly arid conditions in a westward direction. As in many mountain belts, such hydrologic and topographic gradients are commonly mirrored by a systematic relationship between the oxygen and hydrogen stable isotope ratios of meteoric water and elevation. The glass fraction of isotopically datable volcanic ash intercalated in sedimentary sequences constitutes an environmental proxy that retains a signal of the hydrogen-isotopic composition of ancient precipitation. This isotopic composition thus helps to elucidate the combined climatic and tectonic processes associated with topographic growth, which ultimately controls the spatial patterns of precipitation in mountain belts. However, between 25.5 and 27°S present-day river-based hydrogen-isotope lapse rates are very low, possibly due to deep-convective seasonal storms that dominate runoff. If not accounted for, the effects of such conditions on moisture availability in the past may lead to misinterpretations of proxy-records of rainfall. Here, we present hydrogen-isotope data of volcanic glass (δDg), extracted from 34 volcanic ash layers in different sedimentary basins of the Eastern Cordillera and the Sierras Pampeanas. Combined with previously published δDg records and our refined U-Pb and (U-Th)/He zircon geochronology on 17 tuff samples, we demonstrate hydrogen-isotope variations associated with paleoenvironmental change in the Angastaco Basin, which evolved from a contiguous foreland to a fault-bounded intermontane basin during the late Mio-Pliocene

  17. Late Miocene/Pliocene Ostracod Biostratigraphy from South Carpathian Foredeep, Romania (Badislava-Topolog Area)

    Floroiu, Alina; Stoica, Marius; Vasiliev, Iuliana; Krijgsman, Wout


    The Paratethys epicontinental sea has been an essential paleogeographic feature defining the Eurasian interior since Oligocene. By the end of the Miocene, ongoing tectonic activity in the region determined severe restrictions of the connection of the large former Paratethys sea resulting in the formation of several smaller subbasins: the Pannonian basin, the Dacian basin, the Black Sea and the Caspian Sea. In the western part of the Dacian Basin, the thick and continuous Mio-Pliocene sedimentary successions of the Getic Depression of Romania provide an exceptional opportunity to study the paleoecological changes in the Eastern Paratethys during the time when the Mediterranean and Black Sea experienced important sea level changes related to the Messinian Salinity Crisis. These sedimentary successions were the basis of high-resolution magnetobiostratigraphic studies that allow a detailed correlation to the Geological Time Scale. Here, we present the main characteristics of the ostracod assemblages of the Late Miocene/Pliocene sedimentary succession from Badislava-Topolog section covering the Eastern Paratethys regional Maeotian and Pontian, stages that are, at moment, under ongoing formal stratigraphic definition process. The Mio-Pliocene is exposed in the central part of the Getic Depression, especially Topolog-Arges area, where it riches up to 500 m in thickness being incorporated into a large monocline structure with 15o-20o plungeto the south. The Upper Maeotian deposits from the area have developed mainly in fluviatile-deltaic facies with frequent continental intercalations. The ostracod assemblage is represented by rare fresh water ostracods of Candona, Pseudocandona and Ilyocypris genera, capable to populate unstable environments like flood-plains, lakes and rivers with temporary existence. The scarce Maeotian ostracod fauna from this marginal section differs essentially from the more diversified one of the same age recorded in areas that evolved in basinal

  18. Searching Structural Control on the Evolution of the Reservoir Permeability in the Porphyry Copper-Molybdenum Rio Blanco - Los Bronces District: Structural Geology and Passive Seismic Tomography

    Comte, D.; Carrizo, D.; Vela, I.; Silva, W.


    Understand main factors that controls the crustal permeability related to giant ore deposits is a crucial goal for improving metallogenic models. Subsurface data at distrital scales, remains a key factor to reach that goal, however use of regional geophysical methodologies are still extremely expensive and poorly developed on ore exploration. We present the results associated to distrital structural analyses, combined with passive seismic tomography in a case study in Central Andes. Tectono-magmatic evolution of the Rio Blanco-Los Bronces District (Porphyry Cu-Mo Deposit) involves a complex interaction of different processes along the time which includes: Pre-Mesozoic structural inheritance, Oligo-Miocene extension, Mio-Pliocene orogenic shortening with the respective tectonic inversion associated to the uplift of the Andean western margin. Miocene volcano sedimentary units (Abanico Formation) and Pliocene syn-orogenic volcanic units form the deformed host distrital structure. These rocks are part of a trench-linked Andean deformation belt that accommodates EW shortening by NS- strike faults and NS-axes fault related folds. This structural belt controls the uplift of the western margin of the Andes by tectonic inversion of Miocene rift-type structural geometries. The reservoir structure is interpreted by the emplacement of a batholith in the core of the transfer zone between two NS-strike reverse faults, where the ore bodies are located in the center of an anticline general structure showing NW-SE mineralization trend. In turn, NE trending faults dislocate ore bodies in the transfer zone. The reservoir structure is interpreted by the emplacement of a Mio-Pliocene syntectonic batholith in the middle of a transfer zone between two NS-strike reverse faults, where the ore bodies are located in the axis of the anticlinal general structure. Passive seismic tomography results suggest a NNW-strike zone formed by fractured or/and hydrated rocks. This zone is spatially

  19. Site characterization and site response in Port-au-Prince, Haiti

    Hough, Susan E.; Yong, Alan K.; Altidor, Jean Robert; Anglade, Dieuseul; Given, Douglas D.; Mildor, Saint-Louis


    Waveform analysis of aftershocks of the Mw7.0 Haiti earthquake of 12 January 2010 reveals amplification of ground motions at sites within the Cul de Sac valley in which Port-au-Prince is situated. Relative to ground motions recorded at a hard-rock reference site, peak acceleration values are amplified by a factor of approximately 1.8 at sites on low-lying Mio-Pliocene deposits in central Port-au-Prince and by a factor of approximately 2.5–3 on a steep foothill ridge in the southern Port-au-Prince metropolitan region. The observed amplitude, predominant periods, variability, and polarization of amplification are consistent with predicted topographic amplification by a steep, narrow ridge. A swath of unusually high damage in this region corresponds with the extent of the ridge where high weak-motion amplifications are observed. We use ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) imagery to map local geomorphology, including characterization of both near-surface and of small-scale topographic structures that correspond to zones of inferred amplification.

  20. Tertiary block rotations in the Fars Arc (Zagros, Iran)

    Aubourg, C.; Smith, B.; Bakhtari, H. R.; Guya, N.; Eshraghi, A.


    The Fars arc accommodates the oblique convergence between the Arabic plate and the Iran block. Many geological observations suggest block rotations from regional to local scales. We present palaeomagnetic investigations in the Fars arc and its eastern termination, the Zagros-Makran syntaxis. Sixty-four sites have been sampled covering the Palaeocene Pabdeh Fm. to Mio-Pliocene Agha-Jhari Fm., the latest being the most sampled formation. We document pre-tilting components in all formations. However, coarse fractions of Agha-Jhari clastics formation retain a post-tilting remagnetization. As a whole, block rotations rarely exceed 20°. In the western Fars arc, clockwise and counter-clockwise rotations of small amplitudes are consistent with the torsions observed near the strike slip Kazerun and Mangarak faults. In the Zagros Makran syntaxis, counter-clockwise and clockwise rotations are observed, respectively, in the western and eastern part. This pattern is consistent with an amplification of the shape of the syntaxis. Between Zagros and Makran, palaeomagnetic data support that the present-day arcuate shape of the arc is secondary. We assume that most of the block rotations took place during the Plio-Pleistocene, during a blocking stage of the Zagros-Makran syntaxis. We emphasize the role of Oman Peninsula which plays as an indenter for the propagation of the Fars thrust belt.

  1. Late cenozoic magmatism in the South Patagonian batholith: SHRIMP U-Pb zircon age evidence

    The North Patagonian Batholith (NPB) has a zonal age pattern which includes a well defined belt of Miocene and Mio-Pliocene plutons in its central portion (Pankhurst et al., 1999) which are spatially, and probably genetically related to the Liquine-Ofqui Fault Zone. Previous geochronological studies in the Southern Patagonian Batholith (SPB), as summarized by Bruce et al. (1991), have yielded 9 late Cenozoic K-Ar or Ar-Ar ages out of a total of 116 age determinations. None of these young ages correspond to U-Pb determinations on zircons, and some of the young ages correspond to satellite plutons east of the SPB proper, such as the Torres del Paine intrusion. In this paper we present the first late Cenozoic SHRIMP U-Pb zircon ages in the area of the SPB. The morphology of the analysed zircon crystals is described and leads to some inferences on the methodology and on the geological interpretation of the obtained ages (au)

  2. Identification and environmental interpretation of diagenetic and biogenic greigite in sediments: A lesson from the Messinian Black Sea

    Chang, Liao; Vasiliev, Iuliana; van Baak, Christiaan; Krijgsman, Wout; Dekkers, Mark J.; Roberts, Andrew P.; Gerald, John D. Fitz; van Hoesel, Annelies; Winklhofer, Michael


    (Fe3S4) is a widespread authigenic magnetic mineral in anoxic sediments and is also commonly biosynthesized by magnetotactic bacteria in aqueous environments. While the presence of fossilized bacterial magnetite (Fe3O4) has now been widely demonstrated, the preservation of greigite magnetofossils in the geological record is only poorly constrained. Here we investigate Mio-Pliocene sediments of the former Black Sea to test whether we can detect greigite magnetofossils and to unravel potential environmental controls on greigite formation. Our magnetic analyses and transmission electron microscope (TEM) observations indicate the presence of both diagenetic and bacterial greigite, and suggest a potentially widespread preservation of greigite magnetofossils in ancient sediments, which has important implications for assessing the reliability of paleomagnetic records carried by greigite. TEM-based chemical and structural analyses also indicate the common presence of nickel-substituted diagenetic iron sulfide crystals with a ferrimagnetic greigite structure. In addition, our cyclostratigraphic framework allows correlation of magnetic properties of Messinian Black Sea sediments (Taman Peninsula, Russia) to global climate records. Diagenetic greigite enhancements appear to be climatically controlled, with greigite mainly occurring in warm/wet periods. Diagenetic greigite formation can be explained by variations in terrigenous inputs and dissolved pore water sulfate concentrations in different sedimentary environments. Our analysis demonstrates the usefulness of greigite for studying long-term climate variability in anoxic environments.

  3. Impact of climate changes during the last 5 million years on groundwater in basement aquifers

    Aquilina, Luc; Vergnaud-Ayraud, Virginie; Les Landes, Antoine Armandine; Pauwels, Hélène; Davy, Philippe; Pételet-Giraud, Emmanuelle; Labasque, Thierry; Roques, Clément; Chatton, Eliot; Bour, Olivier; Ben Maamar, Sarah; Dufresne, Alexis; Khaska, Mahmoud; La Salle, Corinne Le Gal; Barbecot, Florent


    Climate change is thought to have major effects on groundwater resources. There is however a limited knowledge of the impacts of past climate changes such as warm or glacial periods on groundwater although marine or glacial fluids may have circulated in basements during these periods. Geochemical investigations of groundwater at shallow depth (80-400 m) in the Armorican basement (western France) revealed three major phases of evolution: (1) Mio-Pliocene transgressions led to marine water introduction in the whole rock porosity through density and then diffusion processes, (2) intensive and rapid recharge after the glacial maximum down to several hundred meters depths, (3) a present-day regime of groundwater circulation limited to shallow depth. This work identifies important constraints regarding the mechanisms responsible for both marine and glacial fluid migrations and their preservation within a basement. It defines the first clear time scales of these processes and thus provides a unique case for understanding the effects of climate changes on hydrogeology in basements. It reveals that glacial water is supplied in significant amounts to deep aquifers even in permafrosted zones. It also emphasizes the vulnerability of modern groundwater hydrosystems to climate change as groundwater active aquifers is restricted to shallow depths.

  4. Origin of the Mile Tilek Tuff, South Andaman: evidence from 40Ar-39Ar chronology and geochemistry

    The Mile Tilek Tuff is one of several consolidated volcanic ash deposits in the Andaman and Nicobar Islands that has preserved evidence of a large-scale volcanic eruption in Southeast Asia. Assumed to be of Mio-Pliocene age (∼ 25-2 Ma), the tuff was thought to have been generated by the Andaman-Indonesia volcanic arc. Little was known about its source volcano because of absence of critical isotope data. To provide accurate age information and determine its source, we dated the tuff by 40Ar-39Ar method and measured its trace element contents and Sr-Nd isotopic ratios. The 40Ar-39Ar plateau age for the whole rock is 0.73 ± 0.16 (2σ) Ma, which suggests that the tuff got deposited much later than previously believed. Chemically, the tuff possesses typical characteristics of subduction zone magmatism. Its Sr-Nd isotopic compositions (87Sr/86Sr = 0.7073 and εNd ≤ 0.9) suggest substantial continental crustal contamination of its source magma, which points to a source volcano in Sumatra. Based on available age information on large-scale volcanic eruptions in Indonesia, we speculate that the Ranau volcano in south Sumatra could have been the source of the Mile Tilek Tuff. (author)

  5. High-resolution U-series dates from the Sima de los Huesos hominids yields 600þN-66 kyrs: implications for the evolution of the early Neanderthal lineage

    Bischoff, James L.; Williams, Ross W.; Rosenbauer, Robert J.; Aramburu Artano, Arantza; Arsuaga, Juan Luis; García García, Nuria; Cuenca Bescós, Gloria


    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mudbreccia underlying an accumulation of the Middle Pleistocene cave bear (Ursus deningeri). We report here on new high-precision dates on the recently discovered speleothem SRA-3 overlaying human bones within the Sima de los Huesos. Earlier analyses of this speleothem by TIMS (thermal-ionization mass-spectrometry) showed the lower part to be indisting...

  6. Refining upon the climatic background of the Early Pleistocene hominid settlement in western Europe: Barranco León and Fuente Nueva-3 (Guadix-Baza Basin, SE Spain)

    Blain, Hugues-Alexandre; Lozano-Fernández, Iván; Agustí, Jordi; Bailon, Salvador; Menéndez Granda, Leticia; Espígares Ortiz, Maria Patrocinio; Ros-Montoya, Sergios; Jiménez Arenas, Juan Manuel; Toro-Moyano, Isidro; Martínez-Navarro, Bienvenido; Sala, Robert


    The Early Pleistocene sites of Barranco León and Fuente Nueva-3 (Guadix-Baza Basin, SE Spain) have yielded thousands of Mode 1 or Oldowan lithic artifacts (both sites) and one tooth (in layer D, formerly 5 of Barranco León), today considered to be some of the earliest evidence of humans in western Europe at ca. 1.2-1.5 Ma. Previous quantitative paleoclimatic reconstructions based on herpetile assemblages indicated that, during the formation of these two sites, the mean annual temperature and mean annual precipitation were higher than they are now in the southeastern Iberian Peninsula, with lower continentality. Here, we propose new climatic reconstructions where the mean monthly temperature and precipitation and the difference between the four driest months and the four rainiest months are estimated. Climatograms are built in order to specify the distribution and variation of temperature and precipitation during the year, and the Aridity Indices of Gaussen, Lautensach-Mayer, Dantin-Revenga and De Martonne are used to characterize ombroclimatic differences. According to these new climatic parameters, rainfall distribution through the year shows considerably higher precipitation in every season except summer and early autumn, which remain drier and thus consistent with a Mediterranean climate pattern. No change is observed in the duration of the aridity period, which remains four months long. However, the value of the Aridity Index of De Martonne is higher than 20 (subhumid climate) in Barranco León and Fuente Nueva-3, whereas today it is lower than 20 (semi-arid climate), suggesting major changes in the ombroclimatic type. These results yield a more precise scenario for the paleoclimatic conditions that prevailed during the late Early Pleistocene in the Guadix-Baza Basin and permit us to contrast the ages obtained from numerical dating and biochronology. The very warm and humid climate reconstructed for both Barranco León and Fuente Nueva-3 suggests that, in accordance with the numerical dating, these two sites are contemporaneous with the particularly warm interglacial peaks of Marine Isotope Stages 43-49 (i.e. between 1.35 and 1.47 Ma). The similarity between reconstructed climates, the high overlap between their estimated precipitation and between the difference of the driest from the rainiest season suggest that these sites may correspond to the same part of a climatic glacial/interglacial cycle, but because the evolutionary degree of the rodent Mimomys savini shows a slightly more derived state for Fuente Nueva-3 than for Barranco León (i.e a short chronological difference between the two sites), they may correspond to two consecutive warm interglacial peaks.

  7. Restoration of the Nanjing 2 Fossil Hominid Calvarium: Morphology and Taxonomic Implications%南京2号人类头骨化石的复位和形态

    张银运; 刘武


    南京2号人类头骨化石仅保留部分的额骨、顶骨、枕骨和颞骨,为一不完整的颅盖骨.其顶骨和枕骨有数条断裂缝,各断块之间有程度不一的错动,致使该颅盖骨显得外形异常.本项研究是对该颅盖骨的错动部分进行复位,结果表明,南京2号头骨有较大的顶骨、较小的上枕鳞相对宽度、可能较大的颅容量.这些形态提示该头骨与直立人有所不同而与早期智人相近.该头骨所具有的角圆枕、颞鳞顶缘形状、枕骨圆枕发育程度、枕骨的枕平面与项平面过渡情况、枕内隆突点与枕外隆突点的距离、头骨骨壁厚度、脑膜中动脉分支情况、头骨枕面观之轮廓线样式等形态细节,还很难作为可靠的依据把南京2号头骨鉴定为直立人.南京2号头骨很大可能是属于智人亚种(Homo sapiens sapiens)中的一员.

  8. A partial distal humerus from the Middle Pleistocene deposits at Bodo, Middle Awash, Ethiopia

    Carretero, José Miguel; Haile Selassie, Yohannes; Rodríguez García, Laura; Arsuaga, Juan Luis


    The Bodo partial distal humerus with an approximate age of 0.6 million years is one of the very few postcranial remains from the African Middle Pleistocene. Despite its fragmentary status, comparisons of the Bodo humerus with other fossil hominid and modern human samples reveal some insights into African hominids of this time period. The Bodo partial humerus displays distal humeral features very common in the European Middle and Late Pleistocene hominids, such as a relatively w...

  9. Beginsels en metodes vir die bepaling van die ouderdom van hominied fossiele en hulle vindplekke

    W. J. van Aardt


    Principles and methods used for the determination of the age of hominid fossils and their discovery sites Paleoanthropologists have an array of physical dating methods developed by researchers in the physical sciences. These techniques permit students of hominid evolution and associated culture to have increasing confidence that the evidence of past hominid morphology as expressed by the fossil finds is being placed in the correct chronological order. This article explains in a simple and str...

  10. Brittle tectonics and state of stress in the basin of Tizi n'Test (High Atlas, Morocco during the Tertiary inversion

    Qarbous, A.


    Full Text Available During the Atlasic compressional phase, the Tizi n’Test Triassic basin underwent a tectonic inversion responsible for the reactivation of the extensional Triassic structures. Contrary to former concepts suggesting a transpressional regime, the NE-SW to WNW-ESE trending faults had a reverse displacement, while the NW-SE to NNW-SSE ones were reactivated as strike-slip faults. The reverse motion of the initially normal faults led to the uplift of the basin and its basement in a pop-up style. This inversion is also responsible for a set of footwall synclines and hanging wall anticlines with variable half-wavelength, and related to basement reverse faulting. Striation analysis with the help of software R4DT was carried out at 45 sites in order to determine the state of stress. The 25 most reliable tensors show that the main compressive stress £m1 trends NW-SE to NNE. Analysis of the spatial distribution of the £m1 axis shows a main maximum at N012 and two secondary axes at N123 and N147. In absence of an absolute or relative chronology of the events, we interpret these directions as related to two distinct events, the age of which should be, by comparison with other studies, pre-Mio-Pliocene for the N012 phase and Mio-Pliocene for the NW-SE phase.Durante la fase de compresión Atlásica, la cuenca Triásica de Tizi n’Test ha sufrido un proceso de inversión tectónica responsable de la reactivación de las estructuras extensionales Triásicas. A diferencia de las teorías anteriores que hablaban de un régimen transpresivo, las fallas NE-SO a ONO-ESE han sido inversas, mientras que las de direcciones NO-SE a NNO-SSE han sido reactivadas en su mayoría como fallas de desgarre. El juego inverso de las fallas inicialmente normales provocó el levantamiento de la cuenca y su zócalo paleozoico mediante un estilo de “pop-upâ€�. Esta inversión también generó un conjunto de sinclinales en los compartimientos inferiores y

  11. Kinematics of a sigmoidal fold and vertical axis rotation in the east of the Zagros Makran syntaxis (southern Iran): Paleomagnetic, magnetic fabric and microtectonic approaches

    Smith, B.; Aubourg, C.; Guézou, J. C.; Nazari, H.; Molinaro, M.; Braud, X.; Guya, N.


    The Zagros Simple Fold Belt is characterized by elongated, curved, or sigmoidal folds. The trend of these structures together with the structural style, change suddenly across the Zagros-Makran syntaxis which separates the continental collision domain of Zagros from the oceanic subduction one in Makran. This work focuses on the Minab anticline, outcropping in the easternmost part of Zagros. In order to understand the kinematics of a sigmoidal fold and underscore possible vertical axis rotations in the eastern side of the syntaxis, we performed a joint study of magnetic fabric, microtectonics and paleomagnetism of the northern termination of this fold. The two limbs have been sampled (7 sites, 134 samples) along three cross-sections corresponding to three different orientations of the fold axis. The rocks are weakly deformed fine-grained Mio-Pliocene reddish siltstones. The shortening directions deduced from both magnetic fabric analysis and microtectonic observations are consistent with each other, they are horizontal and roughly perpendicular to the local fold axis, following the torsion of the fold hinge line, and indicating a tectonic origin of the magnetic fabric. Rockmagnetic analyses (thermomagnetic curves, hysteresis loops) point to the presence of magnetite in the PSD and MD ranges as the main magnetic carriers, together with a minor contribution from hematite. Apart from a post-tilting sub-actual VRM and/or CRM (component A), paleomagnetic analyses yield mainly two pre-tilting magnetization components: Component B is carried by magnetite, spanning the intermediate to high unblocking temperature range (300 °C ≤ Tubs ≤ 580 °C). Component C has unblocking temperatures characteristic of hematite (580 °C ≤ Tubs ≤ 680 °C). Both are ante-folding, based on positive reversal and fold tests, inside each of the cross-section but also for the three sections together. However, because component C is biased by some inclination flattening, only component B is

  12. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

    Tibaldi, A.; Corazzato, C.; Rovida, A.


    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognized four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. The following two events, of Pliocene age, are characterized by lower shortening amounts; they occurred first by reverse faulting with a NW-SE-trending greatest principal stress ( σ1, computed with striated fault planes) and a vertical least principal stress ( σ3), followed by pervasive strike-slip faulting with the same NW-SE-trending σ1 and a horizontal NE-SW σ3. The fourth event, dating to the late Pliocene-Quaternary is characterized by normal faulting: the σ3 still trends NE-SW, whereas the intermediate principal stress σ2 exchanged with σ1. Volcanism accompanied both the contractional, transcurrent and extensional tectonic phases. The Mio-Pliocene compression appears directly linked to a rapid convergence and an apparently important coupling between the continental and oceanic plates. The E-W to WNW-ESE direction of shortening of the Miocene structures and the NW-SE σ1 of the Pliocene structures seem to be more linked to an intra-Andean re-orientation of structures following the WNW-directed absolute motion of the South-American Plate. The extensional deformations can be interpreted as related to gravity forces affecting the highest parts of the volcanic belt in a sort of asymmetrical (SW-ward) collapse of the belt.

  13. Modes of rifting in magma-rich settings: Tectono-magmatic evolution of Central Afar

    Stab, Martin; Bellahsen, Nicolas; Pik, Raphaël.; Quidelleur, Xavier; Ayalew, Dereje; Leroy, Sylvie


    Recent research in Afar (northern Ethiopia) has largely focused on the formation of the present-day ocean-continent transition at active segments (e.g., Manda Hararo). However, the Oligo-Miocene history of extension, from the onset of rifting at ~25 Ma to the eruption of the massive Stratoïd flood basalts at ~4 Ma, remains poorly constrained. Here we present new structural data and radiometric dating from Central Afar, obtained along a zone stretching from the undeformed Oligocene Ethiopian plateau to the Manda Hararo and Tat'Ale active volcanic segments. Basaltic and rhyolitic formations were mapped in two key areas corresponding to the proximal and distal parts of a half-rift. We present a balanced composite cross section of Central Afar, reconstructed using our new data and previously published geophysical data on the crustal structure. Our main findings are as follows: (1) Extension during the Mio-Pliocene corresponds to a "wide rift" style of rifting. (2) The lower crust has been underplated/intruded and rethickened during rifting by magmatic injection. (3) Our restoration points to the existence of midcrustal shear zones that have helped to distribute extension in the upper crust and to localize extension at depth in a necking zone. Moreover, we suggest that there is a close relationship between the location of a shear zone and the underplated/intruded material. In magma-rich environments such as Central Afar, breakup should be achieved once the initial continental crust has been completely replaced by the newly, magmatically accreted crust. Consequently, and particularly in Afar, crustal thickness is not necessarily indicative of breakup but instead reflects differences in tectono-magmatic regimes.

  14. Paratethys forcing of the Messinian Salinity Crisis

    Krijgsman, Wout; Van Baak, Christiaan; Flecker, Rachel; Grothe, Arjen; Marzocchi, Alice; Stoica, Marius; Vasiliev, Iuliana


    During the Messinian Salinity Crisis (5.97-5.33 Ma), there is increasing evidence for the presence of fresh water input, not only during the final Lago-mare stage but even during times of evaporite formation. Here we present new strontium isotopic data from two well-dated Messinian sections in the Black and Caspian seas, which show remarkably similar Sr-values as the ones recorded in the Mediterranean during the final phase of the salinity crisis. This strongly suggests that a major fresh water pulse in the Mediterranean originated from the Paratethys. It highlights the importance of a Mediterranean-Black Sea connection during the entire MSC, adding an enormous drainage basin to the Mediterranean water balance. The presence of Paratethyan fauna in the Mediterranean Lago-Mare deposits has fuelled long-lasting controversies over the connectivity between the Mediterranean and Paratethys and contemporary sea level drops in both basins. We furthermore use results of sub-precessional climate simulations to calculate the freshwater budget of the Mediterranean and Paratethys in the Messinian. Using these numerical constraints, we propose a Mediterranean outflow pump as an alternative scenario for the most dramatic hydrological changes in the MSC. This "pump" mechanism significantly enhanced Paratethyan inflow to the Mediterranean, creating 1) suitable conditions for gypsum to form and 2) Lago-mare fauna to migrate and thrive. When the Mediterranean sea level finally reached the height of the Gibraltar sill, Mediterranean outflow restarted there and enhanced exchange with the Atlantic. During this reorganisation of the circulation, brackish and hypersaline waters were pumped out of the Mediterranean, and open marine conditions were re-established without major flooding at the Mio-Pliocene boundary.

  15. Post Tyrrhénian deformation analysis in the Sahel coast (Eastern Tunisia): seismotectonic events implication

    Mejrei, H.; Ghribi, R.; Bouaziz, S.; Balescu, S.


    The eastern coast of Tunisia is characterized by Pleistocene coastal deposits considered as a reference of interglacial high sea levels. In this region, the stratigraphy of Tunisian Pleistocene deposits was first established on the basis of geomorphological, lithostratigraphic, biostratigraphic criteria and U/Th data. They have been subdivided into three superimposed formations, from the oldest to the recent "Douira, Rejiche and Chebba" including coastal marine (Strombus bubonius), lagoonal and eolian sediments. These marine formations are organized into parallel bars to the actual shoreline overlaying unconformably the Mio-Pliocene and "Villafranchian" deposits. A luminescence dating method IRSL applied to alkali feldspar grains from the two sandy marines units of the Douira formation demonstrate for the first time the presence of two successive interglacial high sea level events correlative of MIS 7 and MIS 9. These sandy marine units are separated by a major erosional surface and by a continental pedogenised loamy deposit related to a low sea level event which might be assigned to MIS 8. Variations in the height of these marine unit (+13 to +32m) in the Sahel coast reflect a significant tectonic deformations and show precious geomorphological and tectonic markers. An extensive brittle deformations analysis has been carried out in several sites. A detailed analysis of fracturing is based on studies of fault-slip data population and of joint sets. It allows reconstructions of post Tyrrhenian stress regimes which are characterized by N170-016 compression and N095-100 extension. In this paper we present, the combination of IRSL data applied to these raised marine deposits and a reconstruction of tectonic evolution in term of stress pattern evolution since the Tyrrhenian allowed us to assign an accurate the recent tectonic calendar. These reconstituted events will be replaced and will be discussed in the regional setting of sismotectonic activities of the north

  16. Vicariance and Its Impact on the Molecular Ecology of a Chinese Ranid Frog Species-Complex (Odorrana schmackeri, Ranidae.

    Yongmin Li

    Full Text Available Paleogeological events and Pleistocene climatic fluctuations have had profound influences on the genetic patterns and phylogeographic structure of species in southern China. In this study, we investigated the population genetic structure and Phylogeography of the Odorrana schmackeri species complex, mountain stream-dwelling odorous frogs, endemic to southern China. We obtained mitochondrial sequences (1,151bp of the complete ND2 gene and two flanking tRNAs of 511 individuals from 25 sites for phylogeographic analyses. Phylogenetic reconstruction revealed seven divergent evolutionary lineages, with mean pairwise (K2P sequence distances from 7.8% to 21.1%, except for a closer ND2 distance (3.4%. The complex geological history of southern China drove matrilineal divergence in the O. schmackeri species complex into highly structured geographical units. The first divergence between lineage A+B and other lineages (C-G had likely been influenced by the uplift of coastal mountains of Southeast China during the Mio-Pliocene period. The subsequent divergences between the lineages C-G may have followed the formation of the Three Gorges and the intensification of the East Asian summer monsoon during the late Pliocene and early Pleistocene. Demographic analyses indicated that major lineages A and C have been experienced recent population expansion (c. 0.045-0.245 Ma from multiple refugia prior to the Last Glacial Maximum (LGM. Molecular analysis suggest that these seven lineages may represent seven different species, three described species and four cryptic species and should at least be separated into seven management units corresponding to these seven geographic lineages for conservation.

  17. Depósitos epitermales de baja sulfuración ricos en sulfuros de metales base, distrito aurífero La Carolina, San Luis, Argentina

    Gallard-Esquivel María Cecilia


    Full Text Available Low-sulfidation epithermal base-metal sulfide-rich deposits, La Carolina gold-bearing district,San Luis, Argentina. La Carolina gold-bearing district is located at the western end of the Metallogenetic Belt of San Luis, which is spatially and genetically related to the mesosilicic volcanism of mio-pliocene age. The volcanic arc experienced an eastward migration, due to the flattening of the Nazca plate in the segment 27°-33°S, known as the Pampean flat-slab. At La Carolina, the volcanic activity occurred between 8.2 and 6.3 Ma. It encompasses lavas and pyroclastics of andesitic, dacitic, latitic and trachytic composition. The mesosilicic magmas belong to normal to high-k calc-alkaline and shoshonitic suites. Structural analysis shows that previous structures have strongly controlled the emplacement of volcanic rocks and related mineral deposits at La Carolina allowing to define a pullapart.In this gold-bearing district there are eigth small mineralized prospects. The mineralogy consists of pyrite, arsenic rich pyrite, galena, sphalerite, marcasite, melnikovite, chalcopyrite, pyrrhotite, arsenopyrite, tennantitetetrahedrite, digenite, covellite, bornite, pyrargiryte, hessite, silvanite, pearceite, argirodite, gold, silver, greigite, boulangerite, jamesonite and electrum. The gangue consists of quartz, calcite, chalcedony and minor adularia.The hydrothermal alteration is widespread and comprise phyllic and argillic mineral assemblages characterized by sericite, illite, interstratified I/S, and silicic; propylitic alteration is also present as an outer halo. Fluid inclusions studies show that the formation temperatures range between 230º to 330º C. Boiling and mixing with meteoric water led to mineral precipitation. Based on the mineralogy, textures, hydrothermal alteration, formation temperatures,fluid chemistry and prospective geochemistry the mineralizations have been classified as low-sulfidation epithermal base-metal sulfide-rich deposits.

  18. Gravimetry contributions to the study of the complex western Haouz aquifer (Morocco): Structural and hydrogeological implications

    Chouikri, Ibtissam; el Mandour, Abdennabi; Jaffal, Mohammed; Baudron, Paul; García-Aróstegui, José-Luis; Manar, Ahmed; Casas, Albert


    This study provides new elements that illustrate the benefits of combining gravity, structural, stratigraphic and piezometric data for hydrogeological purposes. A combined methodology was applied to the western Haouz aquifer (Morocco), one of the main sources of water for irrigation and human consumption in the Marrakech region. First, a residual anomaly map was calculated from the Bouguer anomaly data. The computed map provided information on the ground density variation, revealing a strong control by a regional gradient. We then used various filtering techniques to delineate the major geological structures such as faults and basins: vertical and horizontal derivatives and upward continuation. This technique highlighted news structures and provided information on their dip. The gravity anomalies perfectly delineated the basement uplifts and the sedimentary thickening in depressions and grabens. The interpretation of gravimetric filtering, geological and hydrogeological data then highlighted two types of groundwater reservoirs, an unconfined aquifer hosted in conglomeratic mio-pliocene and quaternary rocks, covering the entire western Haouz and a deep confined aquifer contained in cenomanian-turonian limestone and eocene dolomitic formations in the south. Combining piezometric and residual anomaly maps revealed that groundwater flow and storage was in perfect agreement with the structures showing a negative anomaly, while structures with positive anomalies corresponded to groundwater divides. The study of gravity gradient zones by contact analysis enhanced the existing structural pattern of the study area and highlighted new structures, mainly oriented N70 and N130. The results of this study present a common framework and provide a notable step forward in the knowledge of the geometry and the groundwater flow pattern of the western Haouz aquifer, and will serve as a solid basis for a better water resource management.

  19. Delineation of sub-pixel level sedimentary litho-contacts by super resolution mapping of Landsat image

    Shanmuga Priyaa, S.; Sanjeevi, S.


    To delineate the geological formation at the surface, satellite image classification approaches are often preferred. This study aims to produce a super resolved map with better delineation of the litho-contacts from the medium resolution Landsat image. Conventionally used per-pixel classification provides an output map at the same resolution of the satellite image, while the super resolved map provides the high resolution output map using the medium resolution image. In this study, four test sites are considered for delineating different litho-contacts using super resolution mapping approach in Cuddalore district, southern India. The test sites consists of charnockite, fissile hornblende-biotite gneiss, marine sandstone and sandstone with clay, limestone with calcareous shale and clay, clay with limestone bands/lenses, mio-pliocene and quaternary argillaceous and calcareous sandstone, fluvial and fluviomarine formations. This work compares the per-pixel, super resolved output derived from linear spectral unmixing (LSU) based HNN and spectral angle mapper (SAM) based HNN approaches. The super resolution mapping approach was performed on the medium resolution (30 m) Landsat image to obtain the litho-contact maps and the results are compared with the existing maps and observations from field visits. The results showed improved accuracy (90.92%) of the map prepared by the SAM based super resolution approach compared to the LSU based super resolution approach (90.14%) and the maximum likelihood classification approach (83.74%). Such an improved accuracy of the super resolved map (6 m resolution) is due to the fact that the lithological mapping is done not merely at the resolution of the image, but at the sub-pixel level. Hence, it is inferred that super resolution mapping applied to multispectral images may be preferred for mapping lithounits and litho-contacts than the conventional per-pixel and sub-pixel image classification methods.

  20. Origin of the groundwater salinity and geochemical processes in detrital and carbonate aquifers: Case of Chougafiya basin (Central Tunisia)

    Farid, Intissar; Zouari, Kamel; Rigane, Adel; Beji, Ridha


    Comprehensive investigations of groundwaters were performed in the detrital and carbonate aquifers of the Chougafiya basin, central Tunisia. In the present review, hydrochemistry and isotopic tools were combined to get an insight into the processes controlling mineralization, recharge conditions, flow pattern of groundwater and C chemistry in the investigated hydrological system. Analysis of the dissolved constituents revealed that several processes controlled the observed chemical composition: (i) the dissolution of evaporitic minerals, (ii) cation exchange reactions, (iii) sulfate reduction under anaerobic conditions, (iv) incongruent dissolution of carbonate minerals (calcite, dolomite) coupled with gypsum dissolution and calcite precipitation, and (v) silicates weathering. Data inferred from 18O and deuterium isotopes in groundwater samples indicated recharge with modern rainfall. Water characterized by lower δ18O and δ2H values is interpreted as recharged by non-evaporated rainfall originating from Mediterranean and Atlantic air masses. However, water with relatively enriched δ18O and δ2H contents is thought to reflect the occurrence of an evaporation process related to the long term practice of flood irrigation. The radiogenic (3H) isotope data provided insight into the presence of two recharge periods in the investigated groundwaters. Waters with 3H contents of 1 TU clearly suggested the occurrence of a contemporaneous recharge probably during the last two decades. Carbon isotopes provided some insights into the timescales of groundwater flow, but mainly revealed that main sources of C are active in the system. These are likely: dissolved biogenic CO2, carbonate dissolution and incongruent reaction of the carbonate matrix. Mean residence times were determined after correction of the initial activities for dead C from the rock matrix and suggest ages ranging from the present day to the Holocene in both Upper Cretaceous and Mio-pliocene groundwaters.

  1. Dental remains from Atapuerca-TD6 (Gran Dolina site, Burgos, Spain).

    Bermúdez de Castro, J M; Rosas, A; Nicolás, M E


    A descriptive and comparative study of the human dental remains recovered from level six (Aurora stratum) of the Gran Dolina (TD) site, Sierra de Atapuerca, northern Spain, is presented. The TD6 dental sample consists of two deciduous and 28 permanent teeth, belonging to a minimum of six individuals. Paleomagnetic analyses of the TD sequence suggest an age for the Aurora stratum of greater than 780 ka. The associated fossil macro- and micrommals are consistent with a date for the Atapuerca-TD6 hominids at the end of the Early Pleistocene. As a whole, the size of the TD6 teeth is large and comparable to that of the African Lower Pleistocene hominids. Most morphological dental traits are plesiomorphic for the genus Homo, whereas the shape analysis has revealed some size-related trends that differ from those seen in early Homo. Thus, the relative size increase of the maxillary and mandibular anterior teeth and buccolingual diameter of the first molars, the reduction of the third molars and lower canines, and the P(3)>P(4)size sequence are all characteristic of the population represented by the TD6 hominids. The morphological evidence suggests that the TD6 hominids are closer to African Lower and early Middle Pleistocene hominids than they are to European Middle Pleistocene hominids. However, some dental traits of the TD6 hominids, such as the expansion of the anterior teeth, the P(3)>P(4)size sequence, and the morphology of the lower canine also suggest an evolutionary continuity between the population represented by these hominids and the European Middle Pleistocene population. Furthermore, dental evidence indicates that the TD6 hominids are clearly distinct from Asian H. erectus. Dental evidence also suggests that the TD6 hominids could represent an evolutionary connection between H. ergaster and H. heidelbergensis. PMID:10496999

  2. The ischium and hip extensor mechanism in human evolution.

    McHenry, H M


    Although it is commonly stated that the ischia of the late Pliocence-early Pleistocene hominid fossils are long and ape-like, new interpretations show this view to be falacious. An important new theory proposed by Robinson concludes that the gracile form of early hominid was an efficient biped, but the robust form was a less efficient biped and was adapted for tree climbing. Interpretation of the ischium is crucial to this idea. The present study shows that (1) the gracile and robust australopithecine ischia had similar relative lenths and (2) that the hamstring mechanism was probably very similar in the two forms of South African early hominid. PMID:808140

  3. Eroding and Inflating the Atacama Desert, Chile: Insights Through Cosmogenic 10-Be, 26-Al and 21-Ne

    Heimsath, A. M.; Jungers, M. C.; Amundson, R.; Balco, G.; Shuster, D. L.


    quantify surface chronologies as well as the processes shaping these unusual landscapes. To do so we have combined standard surface exposure dating with an application of the burial and profile-dating methodology to surfaces that are expanding by salt inflation. Profiles of these nuclides are used to test simple end-member models for the timescale of surface inflation and initial results support Mio-Pliocene ages for landscapes previously dated by other methods. We also use profiles and burial-age methods to date and better estimate potential inheritance in the nuclide signals for extensive cobble deposits thought to originate from the Andes prior to the onset of hyperaridity. Preliminary results support Miocene deposition, which may suggest a significantly more recent onset time for hyperaridity than others have estimated.

  4. Sedimentology, paleontology and age of the Ayacara and Lago Ranco formations (south-central Chile, 40°- 42°S). Tectonic implications.

    Encinas, Alfonso; Zambrano, Patricio; Bernabe, Pablo; Finger, Kenneth; Buatois, Luis; Duhart, Paul; Valencia, Victor; Fanning, M.; Herve, Francisco


    Deep-marine, Mio-Pliocene strata correlative with the Navidad Formation crop out in different areas along the forearc of south-central Chile (~34°-41°) and have also been recognized in boreholes drilles on the continental shelf. However, at Lago Ranco (40°S) and Ayacara (42°) there are outcrops of marine strata whose age and correlation with these units remain uncertain. These deposits consist of rhythmic successions of sandstone and siltstone representing facies similar to those of the Navidad and correlative formations. These marine successions are known ase the Estratos de Lago Ranco and Ayacara formations. They both crop out in the western Andean Cordillera near the limit with the Intermediate Depression at Lago Ranco and the submerged equivalent of this physiographic unit at Ayacara. There are very few studies carried out on these units and most of them consist on internal reports and unpublished theses.In order to unravel the sedimentary enviroment, age and tectonic history of this area during the Neogene we carried out sedimentological, ichnological and micropaleontological studies. In addition, we carried out U-Pb dating in detrital zircons (LAICPMS and SHRIMP). Our studies show the presence of sedimentary features and ichnofacies typical of deposition in a deep-marine environment for these units..In agreement, benthic foraminifers (Ciclamina incisa and Siphonodosaria sangrinensis) indicate lower bathial depths (1500 m). U-Pb (LAICPMS and SHRIMP) indicate a maximum depositional age of around 20 Ma for these units. In agreement, the occurrence of the planktic foraminifer species Globorotalia siakensis (P22-N14), Globigerinoides quadrilobatus (N6-Recent) and Globigerinoides sikanus (N8-N9) in strata of the Ayacara Formation suggest an early-middle Miocene age for this unit. These data indicate that the area corresponding to the western Main Andean Cordillera in south central Chile, was subjeted to major subsidence during the early-middle Miocene. Major

  5. Neogene Palynology of the Snake River Plain: Climate Change and Volcanic Effects.

    Davis, O. K.; Ellis, B.; Link, P.; Wood, S.; Shervais, J. W.


    Preliminary palynological analyses of lake sediment and inter-flow samples reveal environmental and vegetation changes in response to climatic and volcanic events over the late Neogene. On the evolutionary timescale, sagebrush steppe has expanded and coniferous and deciduous forests have declined. In part this trend has followed the cooling and drying of the late Neogene, but volcanic impact may also be recorded in the effects of long-term subsidence and in periodic deposition of volcanic tephra. The most detailed palynological record yet published for the region (Thompson, 1992) records increasing pine and juniper percentages and decreasing sagebrush and Sarcobatus percentages spanning the Pliocene Glenns Ferry Formation and Pleistocene Bruneau Formation. Palynology of a well in Lake Idaho sediments (Canyon County, Davis, this abstract) shows the same decline of sagebrush and Sarcobatus, but records decreasing juniper percentages during the Pliocene. These Lake Idaho records are spanned by the palynology of the Great Salt Lake (Davis, 2002), which records a modern pollen flora from the late Miocene onward. Salt sage and sagebrush steppe developed progressively from the late Miocene through the Holocene, with peaks in sagebrush pollen percentages during the Mio- Pliocene transition and the late Pleistocene. The Great Salt Lake and Glenns Ferry records both include low percentages of the pollen of deciduous forest taxa such as oak and elm throughout the Pliocene and sporadically into the Pleistocene. Recent studies of soils associated with volcanic tephra reveal a Pliocene upland with abundant grass and high percentages of the pollen and spores of aquatic vegetation: a landscape with drainages choked by ash falls. Palynology above the Fossil Gulch Ash (Hagerman Valley) contains abundant charcoal and high percentages of the pollen of mountain conifers, suggesting devastation of the local vegetation and erosion into Lake Idaho from the surrounding mountains

  6. Using 10Be cosmogenic surface exposure dating to determine the evolution of the Purgatorio active fault in the Andean forearc, southern Peru

    Carlos, Benavente; Swann, Zerathe; Laurence, Audin; Fabrizio, Delgado; Marianne, Saillard; Sarah, Hall R.; Aster Team


    Active transpressive deformation has been occurring along the Andean hyperarid forearc for the last 3 Myrs but many of these faults are still not described even if able to produce large damaging earthquakes. Active faulting along the northern part of the Arica Bend can be recognized due to the presence of well-preserved and sharp fault scarps indicating recent surface slip. During the Mio-Pliocene, deposition within the forearc continental basins resulted in the formation of vast fan deposits and conglomerates of the Moquegua Formation, which can be considered as bedrock in this exposure study (~45-4 Ma; Tosdal et al., 1984; Sebrier et al., 1988a; Roperch et al., 2006). The typical vertical Purgatorio fault scarps offset both the Moquegua bedrock and several younger geomorphic features associated with formation outcroping vertically along the fault scarp. These samples are well-suited to the application of in situ produced cosmogenic radionuclides for surface exposure dating, as the hyperarid region has extremely low erosion rates. We sampled the scarp away from any significant drainage so as to avoid possibly disturbed areas. The sampling did involve extracting quarzite conglomeratic material along the bedrock scarp and on the upper surrounding crests. The aim has been to measure Berylium-20 TCN (Terrestrial in situ Cosmogenic Nuclides) concentrations to determine exposure age as a function of height on the scarp. This has been successfully employed on one scarp in Italy based on Chlorine-36 TCN (Palumbo et al., 2004). However, slow faults behaviour remains unclear and more contributions are needed. Quaternary activity of the Purgatorio fault system was evidenced by Hall et al. (2008). They highlighted a vertical offset of about ~100 m for a pediment surface intercepted by the fault, and dated at ~280 ka. Considering that the pediment surface is horizontal, this would gave a maximum of ~0.3 mm/yr of vertical deformation since 280 ka. Our new data provide evidences

  7. Mn oxides as efficient traps for metal pollutants in a polyphase low-temperature Pliocene environment: A case study in the Tamra iron mine, Nefza mining district, Tunisia

    Decrée, Sophie; Ruffet, Gilles; De Putter, Thierry; Baele, Jean-Marc; Recourt, Philippe; Jamoussi, Fakher; Yans, Johan


    The Tamra mine, located in the Nefza mining district (NW Tunisia), exploits a 50 m-thick layer of Mio-Pliocene sediments that are heavily mineralized with Fe and other metals (Mn, Pb, Zn), especially in its eastern part, which is highly mineralized in Mn and known as the "manganiferous zone". The textural and geochemical studies of manganiferous minerals in the Tamra mine have allowed the determination of four main paragenetic stages. Stages 1 and 2 relate to the main pedogenetic event that gave rise to the currently exploited Fe ore deposit. The last two stages relate to mineralizing events closely connected with hydrothermal circulation and leaching of underlying mineralization of the Sidi Driss Pb-Zn sedex deposit, with subsequent crystallisation in the supergene environment. Stage 3 is characterized by the formation of massive romanechite, hollandite and Sr-cryptomelane, while stage 4 results in the formation of coronadite and chalcophanite. 39Ar- 40Ar analyses performed on hollandite (stage 3) and coronadite (stage 4) samples yielded ages of 4.7 ± 0.1 Ma and 3.35 ± 0.07 Ma, respectively. Tentative 39Ar- 40Ar analyses on chalcophanite provided aberrant results, due to the poor argon retention in this layer-structure mineral. The youngest age corresponds to the late phase of the late Alpine extension event in northern Tunisia, evidenced through an increased regional thermal gradient as well as by a N-S set of normal faults and fractures. The Tamra mine is obviously a polyphase mineral deposit, recording several distinct metal inputs, part of them originating from the underlying Sidi Driss Pb-Zn deposit, while another part is provided by hydrothermal circulations forced by the high thermal gradient. Three springs flowing from the Tamra ore series are regular sources for drinking water used by the local population. Although the Alpine thermal gradient could have facilitated extensive mixing between subsurface oxidizing meteoric fluids and deep reducing

  8. Rapid hydrological response to central Andean Plateau uplift, NW-Argentina

    Rohrmann, Alexander; Sachse, Dirk; Strecker, Manfred R.; Mulch, Andreas; Pingel, Heiko; Alonso, Ricardo N.


    sediment accumulation space in an early intermontane setting. After 6.5 Ma the presence of an efficient orographic barrier is compatible with the inference of rapid (~ 0.5 Ma) basin aridification and a gradual shift to semi-arid vegetation and upward sediment coarsening. Our new high-resolution multi-proxy isotope approach reconstructs the response of the hydrologic cycle, ecosystem, and surface processes to the eastward advance of Mio-Pliocene Andean mountain building in unprecedented detail.

  9. Diets and environments of late Cenozoic mammals in the Qaidam Basin, Tibetan Plateau: Evidence from stable isotopes

    Zhang, Chunfu; Wang, Yang; Li, Qiang; Wang, Xiaoming; Deng, Tao; Tseng, Zhijie J.; Takeuchi, Gary T.; Xie, Gangpu; Xu, Yingfeng


    The timing history and driving mechanisms of C4 expansion and Tibetan uplift are hotly debated issues. Paleoenvironmental evidence from within the Tibetan Plateau is essential to help resolve these issues. Here we report results of stable C and O isotope analyses of tooth enamel samples from a variety of late Cenozoic mammals, including deer, giraffe, horse, rhino, and elephant, from the Qaidam Basin in the northeastern Tibetan Plateau. The enamel-δ13C values are rhino (CD0722, with δ13C values up to -4.1‰). If the Qaidam Basin was as arid as today in the Mio-Pliocene, these data would indicate that the majority of the animals had C3 diets and only a few individuals (besides the exceptional rhino CD0722) may have consumed some C4 plants. Based on geological evidence, however, the Qaidam Basin was probably warmer and more humid during the late Miocene and early Pliocene than today. Thus, these δ13C values likely indicate that many individuals had significant dietary intakes of C4 plants, and the Qaidam Basin had more C4 plants in the late Miocene and early Pliocene than today. Moreover, the Qaidam Basin likely had much denser vegetation at those times in order to support such large mammals as rhinos and elephants. While the δ18O values did not increase monotonously with time, the range of variation seems to have increased considerably since the early Pliocene, indicating increased aridification in the basin. The mean δ18O values of large mammals and those reconstructed for local meteoric waters display a significant negative shift in the late Miocene, consistent with the marine δ18O record which shows a cooling trend in the same period. Taken together, the isotope data suggest a warmer, wetter, and perhaps lower Qaidam Basin during the late Miocene and early Pliocene. Increased aridification after the early Pliocene is likely due to a combined effect of regional tectonism, which resulted in a more effective barrier preventing moisture from the Indian Ocean

  10. Structural Evolution of the Central Venezuelan Andes: Changes From Compression to Strike-slip and Extension

    Hervouet, Y.; Dhont, D.; Backe, G.


    The Venezuelan Andes form a N50°E-trending belt extending from the colombian border in the SW to the Caribbean sea in the NE. The belt is 100 km wide and its highest summits reach 5000 m in its central part. Uplift of the belt is a consequence of the relative convergence between the triangular-shaped Maracaibo crustal block on the west and the Guyana shield belonging to South America. The Maracaibo block is cut by a series of strike-slip faults separating several crustal units. Among these, the easternmost Trujillo triangular block is limited on the west by the N-S left-lateral Valera fault and on the south-east by the NE-trending right-lateral Bocono fault. Our methodology, based on the analysis of radar satellite and digital elevation model imagery and implemented by structural field work and the compilation of seismotectonic data, presents a new understanding of the tectonic evolution of the Venezuelan Andes during the Neogene-Quaternary. We have characterized three stages of deformation. The first, Mio-Pliocene in age, corresponds to the NW-SE Andean compression responsible for the uplift of the Venezuelan Andes. The second tectonic stage is consitent with a strike-slip regime of deformation marked by shearing along the Bocono and Valera faults and hence individualizing the Trujillo block, which has been cut into two smaller triangular wedges. This strike-slip faulting- dominated compressional-extensional tectonic regime started at some point between the Pliocene and the Quaternary and allowed the Trujillo crustal block to move towards the NE. The third stage of deformation corresponds to extension in the Trujillo block and is still active today. The present-day distribution of the deformation in the Venezuelan Andes is consistent with strain partitioning. While compression is restricted on both flanks of the belt, strike-slip and extension occurs in the central part of the mountain range. Extension is associated with the motion of crustal blocks moving

  11. Macroscopic, Microscopic, and Paleo-depositional Features of selected Coals in Arahan, Banjarsari, Subanjeriji, and South Banko Regions, South Sumatra

    Nana Suwarna


    Full Text Available DOI: 10.17014/ijog.v5i4.110The Arahan, Banjarsari, Subanjeriji, and Banko Regions, parts of the Bukit Asam coalfield, is situated in the Lematang Depression of South Palembang Sub-basin, South Sumatera Basin. Twenty two fresh outcrop and subcrop samples of Seam B, A, Benuang, Enim, and Jelawatan of the Mio-Pliocene Muaraenim coals have been analyzed macroscopically and microscopically, to assess the characteristics and depositional environment of the coal present. On the basis of lithotype analysis, accompanied by organic-petrological and SEM analyses, the coal seams of the Muaraenim Formation show variations in the predominance of some macerals, indicating successions of environmental changes. Petrographically, the dominant maceral group is vitrinite, present in high to very high values (69.4 – 97.4 %; whilst the minor one is inertinite showing a low to moderate amount (0.4 – 22.0 %, followed by low to moderate value of exinite (0.4 – 18.2 %. Vitrinite reflectance values are present in a low to moderate level, varying from 0.34 to 0.55 %, with one sample showing value of 0.59 %. Mineral matter dominated by clay minerals, with minor pyrite and carbonate, displays a low degree (0.4 – 5.4 %, with one sample of 12.0 %. Organic facies study tends to indicate that the coals were deposited in a wet forest swamp to limnic zone, within lower delta plain to transgressive area. This condition has supported the depositional setting interpreted from sedimentary facies associations that shows a shallow-water continental margin sequence, varying from a fluvial to deltaic environment. The organic facies concept is thus applicable in basin studies context and has potential to become an additional tool for interpretation of depositional environment.

  12. A new skull of early Homo from Dmanisi, Georgia.

    Vekua, Abesalom; Lordkipanidze, David; Rightmire, G Philip; Agusti, Jordi; Ferring, Reid; Maisuradze, Givi; Mouskhelishvili, Alexander; Nioradze, Medea; De Leon, Marcia Ponce; Tappen, Martha; Tvalchrelidze, Merab; Zollikofer, Christoph


    Another hominid skull has been recovered at Dmanisi (Republic of Georgia) from the same strata in which hominid remains have been reported previously. The Dmanisi site dated to approximately 1.75 million years ago has now produced craniofacial portions of several hominid individuals, along with many well-preserved animal fossils and quantities of stone artifacts. Although there are certain anatomical differences among the Dmanisi specimens, the hominids do not clearly represent more than one taxon. We assign the new skull provisionally to Homo erectus (=ergaster). The Dmanisi specimens are the most primitive and small-brained fossils to be grouped with this species or any taxon linked unequivocally with genus Homo and also the ones most similar to the presumed habilis-like stem. We suggest that the ancestors of the Dmanisi population dispersed from Africa before the emergence of humans identified broadly with the H. erectus grade. PMID:12098694

  13. What Is the Hobbit?

    Powledge, Tabitha M.


    The tiny hominid bones, which a joint Australian-Indonesian team unearthed in 2003 on the Indonesian island of Flores, have quickly become as celebrated (and derided) as any find in the tempestuous history of human paleontology.

  14. Osteometrical and functional analysis and evolution of autopodia in the genus Homo

    Nývltová Fišáková, Miriam


    Roč. 49, - (2003), s. 107-109. ISSN 1210-048X Institutional research plan: CEZ:AV0Z8001916 Keywords : Pleistocene * Fossil Hominids * Palaeolithic Subject RIV: AC - Archeology, Anthropology, Ethnology

  15. Beginsels en metodes vir die bepaling van die ouderdom van hominied fossiele en hulle vindplekke

    W.J. van Aardt


    Full Text Available Principles and methods used for the determination of the age of hominid fossils and their discovery sites Paleoanthropologists have an array of physical dating methods developed by researchers in the physical sciences. These techniques permit students of hominid evolution and associated culture to have increasing confidence that the evidence of past hominid morphology as expressed by the fossil finds is being placed in the correct chronological order. This article explains in a simple and straightforward way the evidence and logic that have led scientists to conclude that hominid fossils are not a few thousand years but at least several million years old. The main focus is on the 40Ar/ 39Ar technique, but other absolute dating techniques such as carbon-14, uranium-thorium-lead and radiocalcium are also reviewed. Relative dating methods are briefly discussed together with paleomagnetism (geomagnetism, optic stimulated luminescence and amino acids.

  16. Thermoluminescence and 234U/230Th dating investigations of hellenic materials

    Thermoluminescence dating has been applied to pottery and kiln materials from Neolithic and Bronze age sites, using the quartz inclusion method. Uranium disequilibrium dating techniques were used to resolve the age of a skull of an early hominid. (author)

  17. Facial Orientation and Facial Shape in Extant Great Apes: A Geometric Morphometric Analysis of Covariation

    Dimitri Neaux; Franck Guy; Emmanuel Gilissen; Walter Coudyzer; Patrick Vignaud; Stéphane Ducrocq


    The organization of the bony face is complex, its morphology being influenced in part by the rest of the cranium. Characterizing the facial morphological variation and craniofacial covariation patterns in extant hominids is fundamental to the understanding of their evolutionary history. Numerous studies on hominid facial shape have proposed hypotheses concerning the relationship between the anterior facial shape, facial block orientation and basicranial flexion. In this study we test these hy...

  18. Significance of some previously unrecognized apomorphies in the nasal region of Homo neanderthalensis.

    Schwartz, J. H.; Tattersall, I.


    For many years, the Neanderthals have been recognized as a distinctive extinct hominid group that occupied Europe and western Asia between about 200,000 and 30,000 years ago. It is still debated, however, whether these hominids belong in their own species, Homo neanderthalensis, or represent an extinct variant of Homo sapiens. Our ongoing studies indicate that the Neanderthals differ from modern humans in their skeletal anatomy in more ways than have been recognized up to now. The purpose of ...

  19. Clavicles, scapulae and humeri from the Sima de los Huesos site (Sierra de Atapuerca, Spain).

    Carretero, J M; Arsuaga, J L; Lorenzo, C


    The scapulae, clavicles and humeri recovered from the Sima de los Huesos (SH) site between 1976 and 1994 are studied. All elements are briefly described anatomically with metrics and compared with other fossil hominids in order to establish the morphological pattern of the SH hominids. A minimum of 13 individuals are represented by the humeri in the SH sample. Almost all of them can be classified as adolescents and young adults. The morphology of the SH hominid shoulder girdle and humeri indicates that much of the shoulder morphology recognized in the later true Neandertal was present in Europe long before they appeared. Thus, this morphological pattern is not exclusive to Neandertals alone. The SH clavicles, scapulae and humeri share with the Neandertals many traits usually considered to be Neandertal specializations. The comparative analysis of the SH evidence suggests that most of the SH and Neandertal shared traits are either primitive features within the genus Homo or even for all hominids, or display high variability within different hominid samples. These traits must be used with caution, or not used at all, in phylogenetic analysis. There are, however, traits that to date have only been detected in the SH hominids and the Neanderials, which could be exclusive to the European phyletic lineage (clade) of Homo. PMID:9300347

  20. From apes to humans: locomotion as a key feature for phylogeny.

    Senut, Brigitte


    If bipedalism has often been considered to be of a crucial interest for understanding hominid evolution, the acceptance of locomotor features to build phylogenies is still far from being a reality in the field. Especially for hominid evolution, it still seems to be difficult to accept that traits, other than craniodental ones, can be useful for defining the major dichotomies. The recent discovery of Australopithecus anamensis suggests a challenging view of the major dichotomy between apes and humans. Whilst it is widely accepted that Ardipithecus ramidus is ancestral to Australopithecus anamensis, which in its turn is ancestral to Australopithecus afarensis and then to later hominids, the postcranial adaptations, which should be taken into account, suggest another branching pattern. Based on the fact that by 4.0 million years two different locomotor patterns can be identified in hominids, two lineages would appear to be present: the "Australopithecine" lineage (with Australopithecus afarensis or Ardipithecus ramidus if the latter is really a hominid sensu stricto) and the "Hominine" lineage (with Australopithecus anamensis = Praeanthropus africanus). PMID:12050904

  1. Age of an Indonesian Fossil Tooth Determined by Electron Paramagnetic Resonance

    Bogard, JS


    The first fossil hominid tooth recovered during 1999 excavations from the Cisanca River region in West Java, Indonesia, was associated with a series of bovid teeth from a single individual that was recovered 190 cm beneath the hominid tooth. The age of the fossil bovid teeth was determined using electron paramagnetic resonance (EPR) analysis as part of an effort to bracket the age of the hominid tooth. The EPR-derived age of the bovid teeth is (5.16 {+-} 2.01) x 10{sup 5} years. However, the age estimate reported here is likely an underestimate of the actual age of deposition since evidence of heating was detected in the EPR spectra of the bovid teeth, and the heating may have caused a decrease in the intensity of EPR components on which the age calculation is based.

  2. Examining time trends in the Oldowan technology at Beds I and II, Olduvai Gorge.

    Kimura, Yuki


    The lithic analysis of the Bed I and II assemblages from Olduvai Gorge reveals both static and dynamic time trends in early hominids' technology from 1.8 to 1.2 m.y.a. The Bed I Oldowan (1.87-1.75 m.y.a.) is characterized by the least effort strategy in terms of raw material exploitation and tool production. The inclusion of new raw material, chert, for toolmaking in the following Developed Oldowan A (DOA, 1.65-1.53 m.y.a.) facilitated more distinctive and variable flaking strategies depending on the kind of raw materials. The unique characters of DOA are explainable by this raw material factor, rather than technological development of hominids. The disappearance of chert in the subsequent Developed Oldowan B and Acheulian (1.53-1.2 m.y.a.) necessitated a shift in tool production strategy more similar to that of Bed I Oldowan than DOA. However, the evidence suggests that Bed II hominids might have been more skillful toolmakers, intensive tool-users, and engaged in more active transport of stone tools than the Bed I predecessors. Koobi Fora hominids maintained a more static tool-using behavior than their Olduvai counterparts due mainly to a stable supply of raw materials. They differed from Olduvai hominids in terms of less battering of cores, consistent transport behavior, and few productions of side-struck flakes, indicating a regional variation of toolmaking and using practice. However, they shared with Olduvai hominids a temporal trend toward the production of larger flakes from larger cores after 1.6 m.y.a. Increased intake of animal resources and the expansion of ranging area of Homo ergaster would have led to the development of technological organization. Technological changes in the Oldowan industry are attested at Olduvai Gorge, Koobi Fora, and Sterkfontein, suggesting that it was a pan-African synchronous phenomenon, beginning at 1.5 m.y.a. PMID:12234546

  3. Dental metric assessment of the omo fossils: implications for the phylogenetic position of Australopithecus africanus.

    Hunt, K; Vitzthum, V J


    The discovery of Australopithecus afarensis has led to new interpretations of hominid phylogeny, some of which reject A. africanus as an ancestor of Homo. Analysis of buccolingual tooth crown dimensions in australopithecines and Homo species by Johanson and White (Science 202:321-330, 1979) revealed that the South African gracile australopithecines are intermediate in size between Laetoli/hadar hominids and South African robust hominids. Homo, on the other hand, displays dimensions similar to those of A. afarensis and smaller than those of other australopithecines. These authors conclude, therefore, that A. africanus is derived in the direction of A. robustus and is not an ancestor of the Homo clade. However, there is a considerable time gap (ca. 800,000 years) between the Laetoli/Hadar specimens and the earliest Homo specimens; "gracile" hominids from Omo fit into this chronological gap and are from the same geographic area. Because the early specimens at Omo have been designated A. afarensis and the later specimens classified as Homo habilis, Omo offers a unique opportunity to test hypotheses concerning hominid evolution, especially regarding the phylogenetic status of A. africanus. Comparisons of mean cheek teeth breadths disclosed the significant (P less than or equal to 0.05) differences between the Omo sample and the Laetoli/Hadar fossils (P4, M2, and M3), the Homo fossils (P3, P4, M1, M2, and M1), and A. africanus (M3). Of the several possible interpretations of these data, it appears that the high degree of similarity between the Omo sample and the South African gracile australopithecine material warrants considering the two as geographical variants of A. africanus. The geographic, chronologic, and metric attributes of the Omo sample argue for its lineal affinity with A. afarensis and Homo. In conclusion, a consideration of hominid postcanine dental metrics provides no basis for removing A. africanus from the ancestry of the Homo lineage. PMID:3099582

  4. Analyse quantitative du réseau hydrographique du bassin versant du Slănic (Roumanie

    Florina Grecu


    Full Text Available L'étude porte sur le bassin versant du Slănic, un affluent du Buzău. Ce bassin de taille relativement réduite (433 km2 est situé dans la région des Carpates et des Subcarpates de la Courbure, région très active sur le plan sismique. Du point de vue lithologique, le bassin du Slănic correspond à des flyschs paléogènes et à des molasses mio-pliocènes. Ces roches peu résistantes ont facilité une forte érosion du relief. Actuellement, les précipitations présentent souvent une forte intensité, et elles se produisent fréquemment après des périodes de sécheresse. Elles sont ainsi très agressives et déclenchent une érosion intense. L'analyse de quelques paramètres morphométriques [grand nombre de segments de cours d'eau d'ordres 1 (5230 et 2 (944 ; densité élevée des segments par rapport à la superficie du bassin (environ 15 segments / km2 ; longueur moyenne réduite des segments d'ordre 1 (260 m par rapport à ceux d'ordre 2 (530 m] s'accorde avec des temps de concentration des eaux courts et une forte énergie des écoulements. La vitesse de réaction aux précipitations des segments d'ordres inférieurs est en outre favorisée par la répartition spatiale des pluies et par les conditions lithologiques.The study is focused on the Slănic basin which has a small size (433 km2. The hydrographical basin of Slănic, situated in the Carpathian and Subcarpathian Curvature, a very active from neotectonical viewpoint area, is a part of the Buzău basin. From a petrographic point of view, the Slănic hydrographic basin belongs to the paleogen flysch deposits (within the Carpathian sector and to the mio-pliocen molasse (within the Subcarpathian area latter formed by predominantely friable rocks which have encouraged deep fragmentation of the relief. Actual rainfalls are often very intensive, and they frequently occur after dry seasons. The analysis of morphometric parameters shows many elementary segments of first

  5. New Constraints on the Timing and Magnitude of Deformation and Basin Exhumation in the Eastern Cordillera of NW Argentina.

    Trimble, J. D.; Carrapa, B.; Stockli, D. F.; Stutz, J.


    could be potentially related to the reactivation of Cretaceous relay-zone structures. Flexural-slip folding is the dominant mechanism of folding within the basin, with centimeter to meter scale fracture-rich and slickenside-rich beds of fine silts acting as primary slip-surfaces between thicker, more competent beds of coarse sand and conglomerate. A newly discovered intra-formational angular unconformity near the base of the Angastaco Fm. documents growth during the early stages of deposition. However, there is no clear evidence of continuous growth up section, implying at least two pulses of significant deformation during syn- and post- Miocene time. New apatite (U-Th)/He thermochronology (AHe) from six samples from the Eocene-Oligocene(?) Quebrada de los Colorados Fm and the Miocene Angastaco Fm (~18 Ma) in the Angastaco and surrounding Pucara and Tin Tin basins yields youngest ages between ca. 13.2 Ma (to the west) and ca. 10.3 Ma (to the east), and correlate with low Uranium content. We interpret these ages as representative of cooling following basin exhumation in the Miocene. The younging of those ages towards the east, together with structural data indicating young Mio-Pliocene deformation, suggests that those ages may be the result of eastward propagation of deformation into the foreland driving basin exhumation.

  6. New insights into the evolution of central Tyrrhenian margin of Italy (northern Latium off-shore area): evidences and constraints from seismic data interpretation

    Buttinelli, M.; Vico, G.; Scrocca, D.; Petracchini, L.; de Rita, D.


    the formation of several small and narrow graben and half-graben basins with NW-SE and NE-SW direction of elongation, filled with up to 600m of conglomeratic, sandy and clayish sediments and a regional unconformity surface on top of the deformed basement. The sedimentation continued with the trasgressive deposition of the Plio-Pleitocene clayish units, separated by a Middle Pliocene unconformity; iii) a final stage of deformation, strictly localized around the Late Pliocene volcanic intrusions of the Tolfa and Ceriti dome complexes. This is associated with local uplift (up to 200m), normal faulting, and radial tilting of the sedimentary units strata of the Mio-Pliocene sedimentary units in the on-shore graben and half-graben filled basins, analogous to the geological setting of the basins recognised in the off-shore part of this area. Gravimetric and Magnetic anomaly data also suggest the possible presence of an off-shore intrusion just in front of the coastline of Civitavecchia city. Seismic reflection data analysis show in the same place a local perturbation of the sedimentation regime of the Plio-Pleistocene units due to the local change of basin morphology.

  7. Extreme extension across Seram and Ambon, eastern Indonesia: Evidence for Banda slab rollback

    J. M. Pownall


    Full Text Available The island of Seram, which lies in the northern part of the 180°-curved Banda Arc, has previously been interpreted as a fold-and-thrust belt formed during arc-continent collision, which incorporates ophiolites intruded by granites thought to have been produced by anatexis within a metamorphic "sole". However, new geological mapping and a re-examination of the field relations cause us to question this model. We instead propose that there is evidence for recent N–S extension that has caused the high-temperature exhumation of hot mantle peridotites, granites, and granulites (the "Kobipoto Complex" beneath low-angle lithospheric detachment faults. Greenschist- to lower-amphibolite facies metapelites and amphibolites of the Tehoru Formation, which comprise the hanging wall above the detachment faults, were overprinted by sillimanite-grade metamorphism, migmatisation and limited localised diatexis to form the Taunusa Complex. Highly aluminous metapelitic garnet + cordierite + sillimanite + spinel + corundum + quartz granulites exposed in the Kobipoto Mountains (central Seram are intimately associated with the peridotites. Spinel + quartz inclusions in garnet, which indicate that peak metamorphic temperatures for the granulites likely approached 900 °C, confirm that peridotite was juxtaposed against the crust at typical lithospheric mantle temperatures and could not have been part of a cooled ophiolite. Some granulites experienced slight metatexis, but the majority underwent more advanced in situ anatexis to produce widespread granitic diatexites characterised by abundant cordierite and garnet xenocrysts and numerous restitic sillimanite + spinel "clots". These Mio-Pliocene "cordierite granites", which are present throughout Ambon, western Seram, and the Kobipoto Mountains in direct association with peridotites, demonstrate that the extreme extension required to have driven Kobipoto Complex exhumation must have occurred along much of the northern

  8. Parametric study of the impact of waste pollutants on groundwater: the case of Abidjan District (Ivory Coast)

    Agnès Kouamé, Amenan; Jaboyedoff, Michel; Tacher, Laurent; Derron, Marc-Henri; Franz, Martin


    Abidjan like numerous African cities is experiencing a significant and uncontrolled population growth. The annual growth rate is estimated at 3.99% by the National Institute of Statistics. This rapid population growth also generates growing needs in general and especially for drinking water and economic activities. In the District of Abidjan, groundwater comes from the Mio-Pliocene age aquifer called "Continental Terminal". This unconfined aquifer is the main source of water supply. Its lithology consists of four levels. Actually only the two upper levels outcrop and constitute the main part of the Continental Terminal aquifer. Some recent studies report a potential overexploitation and pollution of Abidjan groundwater (Jourda, 1986, Kouame 2007, Deh, 2013). This deterioration in water quality could be due to the release of domestic and industrial waste water, pesticide and fertilizer from crops and toxic waste sites containing high doses of organochlorines, of hydrogen sulfide and sulfides. This risk is also linked to the economic activities such as car workshops, gas stations and the sand exploitation in the lagoon. To observe the likely evolution of such contaminants in the subsurface and we developed hydrogeological models that couple groundwater flow and transport with FEFLOW software. The model is composed of a sandy layer where two constant hydraulic heads of 55 m and 0.2 m are imposed on the north and the south respectively. We carried out grain size analysis of some samples (E2, E3, E4, E5, and E6) which shows particle size ranging between 0.0001 mm and 8 mm. This grain size analysis performed by sieving underwater and laser indicates that these five soils are: loamy sand with traces of clay and gravel for E2 and E5; Sandy loam with traces of clay for E3; Sand with traces of clay and gravel for E4 and Sand with traces of silt and clay for E6. Their porosity and average values of permeability coefficient K measured in the laboratory range from 0.2 to 0

  9. The promotion of geomorphosites on salt from Sovata - Praid and Turda using cultural and scientific tourism

    Toma, B.; Irimus, I.; Petrea, D.


    The paper highlights the role of geomorphosites on salt, in experts and specialists training, in geography of tourism and planning, namely, the involvement of educational factor in defining managerial and marketing skills of future specialists in training. Geographical area of investigation belongs to the Transylvanian tectonic basin, overlapped to saliferous tectonic area from eastern Transylvania, represented by Praid - Sovata - Corund anticline and Sic -Cojocna - Turda anticline, analysis is focused on the Praid - Sovata and Turda diapirs. Saliferous area Praid - Sovata - Corund is situated on the contact area of the Transylvanian Basin with neo-eruptiv mountain chain of Eastern Carpathians, Calimani - Gurghiu - Harghita, and at the contact of Târnavelor Plateau with the orogen alignment of Gurghiu - Harghita Mountains. The salt body, in the horizontal plane, has a quasi-circular shape, slightly ellipsoidal, with diameters of 1.2 and 1.4 km, and is estimated to have a burial depth of 2.6 to 2.8 km. The salt massif from Praid, pierce the Mio-Pliocene blanket around and appears at the surface as diapir, flanked by sedimentary rocks that are partially covered by extrusive post-Pliocene volcanic formations and Quaternary deposits. Evaporitic deposits presents a varied lithology represented by gypsum, anhydrite, salt rock, potassium salt and celestine. The salt massif from Turda develops on the anticline Sic -Cojocna - Turda, oriented NE - SW, 2 km NE of Turda's downtown. It has an elongated shape, about 4 km, with widths ranging from 700 m to 200 m and also with a thickness ranging from 750 m to over 1000 m. In terms of stratigraphy, the salt massif is surrounded by deposits belonging to Badenian, Sarmatian and Quaternary. Due to salt dissolution by meteoric waters, carsto-saline lakes were formed, and due to ceiling collapse, because of an intensive exploitation, and infiltrations of rainwater and rivers, antropo-salted lakes were formed. The water and mud of

  10. Geomorpho-pédogenèse dans des accumulations alluviales d'un piémont andin: Étude du contact Andes-Llanos Occidentaux au Venezuela (Région de Guanare-Barinas

    Pouyllau, Daniel


    Full Text Available The piémont in the South-East region of the Andes In Venezuela we study, lying between the towns of Guanare and Barinas, spreads over 150.000 ha of a zone where a dry tropical forest constitutes the climatic vegetation. During the erogenic period of the Andes -i.e. mio-pliocene and quaternary-, a strong erosion produced at the same time a removal of material belonging to the high basins, its transportation towards the depressed areas of the Llanos, and the breaking up of the widespread sheet structures thus constituted, and finally created the present topography with terraces. The study of this piémont thus allows the formulation of a series of hypotheses concerning the géomorphologic evolution of this region.

    [fr] Le piémont sud-oriental des Andes vénézuéliennes étudié et située entre les villes de Guanare et de Barinas, s'étend sur 150.000 ha dans une zone où la forêt sèche tropicale est la végétation climacique. Durant l'orogenèse andine mio-pliocène et quaternaire, une intense érosion a entraîné, en même temps, le déblaiement des matériaux des hauts-bassins, leur transport vers la dépression des Llanos et le dépôt en nappes généralisées; le démantèlement de celles-ci a conduit à la topographie actuelle des terrasses. L'étude de ce piémont permet d'émettre une série d'hypothèses sur l'évolution géomorphologique régionale.
    [es] El piedemonte suroriental de los Andes venezolanos, ubicado entre las ciudades de Guanare y de Barinas, cubre 150.000 has. y su vegetación climácica es el bosque seco tropical. Durante la orogénesis andina, mio-pliocena y cuaternaria, una intensa erosión originó al mismo tiempo el arrastre de los materiales de las cuencas altas, su transporte hacia la depresión de loa Llanos, su deposición en mantos generalizados y el desmantelamiento de los mismos, formando la topografía actual de las terrazas. El estudio de este piedemonte permite emitir una serle de hip

  11. Modeling along-axis variations in fault architecture in the Main Ethiopian Rift: implications for Nubia-Somalia kinematics

    Erbello, Asfaw; Corti, Giacomo; Sani, Federico; Kidane, Tesfaye


    The Main Ethiopian Rift (MER), at the northern termination of the East African Rift, is an ideal locale where to get insights into the long-term motion between Nubia and Somalia. The rift is indeed one of the few places along the plate boundary where the deformation is narrow: its evolution is thus strictly related to the kinematics of the two major plates, whereas south of the Turkana depression a two-plate model for the EARS is too simplistic as extension occurs both along the Western and Eastern branches and different microplates are present between the two major plates. Despite its importance, the kinematics responsible for development and evolution of the MER is still a matter of debate: indeed, whereas the Quaternary-present kinematics of rifting is rather well constrained, the plate kinematics driving the initial, Mio-Pliocene stages of extension is still not clear, and different hypothesis have been put forward, including: polyphase rifting, with a change in direction of extension from NW-SE extension to E-W extension; constant Miocene-recent NW-SE extension; constant Miocene-recent NE-SW extension; constant, post-11 Ma extension consistent with the GPS-derived kinematics (i.e., roughly E-W to ESE-WNW). To shed additional light on this controversy and to test these different hypothesis, in this contribution we use new crustal-scale analogue models to analyze the along-strike variations in fault architecture in the MER and their relations with the rift trend, plate motion and the resulting Miocene-recent kinematics of rifting. The extension direction is indeed one of the most important parameters controlling the architecture of continental rifts and the relative abundance and orientation of different fault sets that develop during oblique rifting is typically a function of the angle between the extension direction and the orthogonal to the rift trend (i.e., the obliquity angle). Since the trend of the MER varies along strike, and consequently it is

  12. Fish as a proxy for African paleogeography: results from both extant and fossil taxa and prospects to constrain faunal exchange pathway through time

    Otero, Olga; Joordens, Josephine; Dettai, Agnès; Christ, Leemans; Pinton, Aurélie


    : relationships between Chad and neighbouring basins throughout the Mio-Pliocene. Pa

  13. La thèse de Paul DEMANGEON un demi-siècle après : une relecture actualisée dans le bassin de l'Orb (Languedoc, France

    Jean-Pierre Larue


    favourable to the elaboration of the Villespassans erosion surface. The Messinian regression of the Mediterranean Sea caused a deep valley incision up to Cessenon for the Orb River and to Montouliers for the Cesse tributary. However, an uplift of the basement with gentle distortions in the Languedocian piedmont seems necessary to explain the upstream erosion in the X micaschists. The Villespassans surface was distorted while the lower Fontcaude surface was not affected. These Mio-Pliocene tectonic movements are responsible of the size increase and of the mineralogical change in the Pliocene deposits.

  14. Effects of Caribbean oceanic plateau shallow subduction on topographic uplift and exhumation of the northwestern Maracaibo block, Colombia

    Sanchez, J.; Mann, P.


    central SP show several slope-break knickpoints and changes in steepness indices by factor of ~1.9, all indicative of fault control in this area; 3) perturbations in stream profiles with change in steepness indices by a factor of ~1.6 occur in the southern SP are interpreted as the expression of the active Santa-Marta Bucaramanga fault system, 4) although most of the knickpoints in SSM profiles seem to be associated with changes in bedrock lithology, the alignments, slope-breaking character, and change in steepness indices by factor of ~1.8-2.2 indicate active ENE-WSW fault control along the south-southeastern edge of the SSM, 5) generally undisturbed profiles at northern SSM suggest current quiescence in rock uplift in this area; and 6) basin modeling of the CRB constrain the most recent uplift event as Mio-Pliocene at rates of 0.15-0.18 mm/yr. We propose that the most likely tectonic mechanism to explain widespread active fault activity and uplift within the SSM and SP is oblique, low-angle (20 degrees), southeastward subduction of the Caribbean plate beneath the area. The present rate of subduction and length of slab would have initiated uplift and fault activity at Early Miocene.

  15. Integrative geomorphological mapping approach for reconstructing meso-scale alluvial fan palaeoenvironments at Alborz southern foothill, Damghan basin, Iran

    Büdel, Christian; Majid Padashi, Seyed; Baumhauer, Roland


    Alluvial fans and aprons are common depositional features in general Iranian geomorphology. The countries major cities as well as settlements and surrounding area have often been developed and been built up on this Quaternary sediment covers. Hence they periodically face the effects of varying fluvial and slope-fluvial activity occurring as part of this geosystem. The Geological Survey of Iran therefore supports considerable efforts in Quaternary studies yielding to a selection of detailed mapped Quaternary landscapes. The studied geomorphologic structures which are settled up around an endorheic basin in Semnan Province represent a typical type of landform configuration in the area. A 12-km-transect was laid across this basin and range formation. It is oriented in north-south direction from the southern saltpan, called "Kavir-e-Haj Aligholi"/"Chah-e-Jam" ("Damghan Kavir"), across a vast sandy braided river plain, which is entering from the north east direction of the city of Shahroud. At its northern rim it covers alluvial sediment bodies, which are mainly constituted by broad alluvial aprons, fed by watersheds in Alborz Mountains and having their genetic origins in Mio-/Pliocene times. During this study a fully analytical mapping system was used for developing a geodatabase capable of integrating geomorphological analyses. Therefore the system must provide proper differentiation of form, material and process elements as well as geometric separation. Hence the German GMK25 system was set up and slightly modified to fit to the specific project demands. Due to its structure it offers most sophisticated standards and scale independent hierarchies, which fit very well to the software-determinated possibilities of advanced geodatabase applications. One of the main aspects of mapping Quaternary sediments and structures is to acquire a proper description and systematic correlation and categorization of the belonging mapping-objects. Therefore the team from GSI and

  16. Evolution de la morphologie claviculaire au sein du genre Homo. Conséquences architecturales et fonctionnelles
    sur la ceinture scapulaire

    Voisin, Jean-Luc


    La clavicule est un os qui a été peu étudié en anthropologie et paléoanthropologie malgré son importance fonctionnelle. Le travail présenté ici est une étude des courbures claviculaires chez les hominidés actuels et chez quelques hominidés fossiles (Homo habilis, Homo ergaster, Homo antecessor et néandertaliens). La morphologie claviculaire en vue supérieure traduit essentiellement les capacités d'élévation du bras de l'individu, alors que la morphologie claviculaire en vue postérieure inform...

  17. The geological, isotopic, botanical, invertebrate, and lower vertebrate contexts for aripithecus ramidus

    Woldegabriel, Giday [Los Alamos National Laboratory; Ambrose, Stanley H [UNIV OF ILLINOIS; Barboni, Doris [CEREGE, FRANCE; Bonneffille, Raymond [CEREGE, FRANCE; Bremond, Laurent [MONTPELLIER, FRANCE; Currie, Brian [MIAMI UNIV, OXFORD, OHIO; Degusta, David [STANFORD UNIV.; Hart, William K [MIAMI UNIV, OXFORD, OHIO; Murray, Alison M [UNIV OF ALBERTA; Renne, Paul R [UC/BERKELEY; Jolly - Saad, M C [NANTERRE, FRANCE; Stewart, Kathlyn M [CANADA; White, Tim D [UC/BERKELEY


    Sediments containing Ardipithecus ramidus were deposited 4.4 million years ago on an alluvial floodplain in Ethiopia's western Afar rift. The Lower Aramis Member hominid-bearing unit, now exposed across a >9-kilometer structural arc, is sandwiched between two volcanic tuffs that have nearly identical {sup 40}Ar/{sup 39}Ar ages. Geological data presented here, along with floral, invertebrate, and vertebrate paleontological and taphonomic evidence associated with the hominids, suggest that they occupied a wooded biotope over the western three-fourths of the paleotransect. Phytoliths and oxygen and carbon stable isotopes of pedogenic carbonates provide evidence of humid cool woodlands with a grassy substrate.

  18. L'outillage lithique du site de dépeçage à Elephas recki ileretensis de Barogali (république de Djibouti)Stone tools from the butchery site with Elephas recki ileretensis of Barogali (Republic of Djibouti)

    Berthelet, Arlette


    Three seasons of excavations (1985-1987) in the Gobaad region of the Republic of Djibouti have unearthed the fossilized skeletal remains of an Elephas recki (1.3-1.6 million years old). Numerous stone artefacts discovered among the bones indicates that the excavation is a butchery site where hominids cut up and perhaps consumed the elephant meat. The discovery of cores and small flakes near the elephant carcass indicates that the hominids knapped choppers and polyhedrons and retouched flakes during the scavenging operation.

  19. The Power of Natural Selection: A Guided Investigation of Three Case Studies

    Beachly, William


    I describe a quantitative approach to three case studies in evolution that can be used to challenge college freshmen to explore the power of natural selection and ask questions that foster a deeper understanding of its operation and relevance. Hemochromatosis, the peppered moth, and hominid cranial capacity are investigated with a common algebraic…

  20. Evolution of Humans: Understanding the Nature and Methods of Science through Cooperative Learning

    Lee, Yeung Chung


    This article describes the use of an enquiry-based approach to the study of human evolution in a practical context, integrating role-playing, jigsaw cooperative learning and scientific argumentation. The activity seeks to unravel the evolutionary relationships of five hominids and one ape from rather "messy" evidence. This approach enhanced the…

  1. Beyond the Pleistocene: Using Phylogeny and Constraint to Inform the Evolutionary Psychology of Human Mating

    Eastwick, Paul W.


    Evolutionary psychologists explore the adaptive function of traits and behaviors that characterize modern Homo sapiens. However, evolutionary psychologists have yet to incorporate the phylogenetic relationship between modern Homo sapiens and humans' hominid and pongid relatives (both living and extinct) into their theorizing. By considering the…

  2. Chromosome Connections: Compelling Clues to Common Ancestry

    Flammer, Larry


    Students compare banding patterns on hominid chromosomes and see striking evidence of their common ancestry. To test this, human chromosome no. 2 is matched with two shorter chimpanzee chromosomes, leading to the hypothesis that human chromosome 2 resulted from the fusion of the two shorter chromosomes. Students test that hypothesis by looking for…

  3. Evolution & Phylogenetic Analysis: Classroom Activities for Investigating Molecular & Morphological Concepts

    Franklin, Wilfred A.


    In a flexible multisession laboratory, students investigate concepts of phylogenetic analysis at both the molecular and the morphological level. Students finish by conducting their own analysis on a collection of skeletons representing the major phyla of vertebrates, a collection of primate skulls, or a collection of hominid skulls.

  4. Blood, bulbs, and bunodonts: on evolutionary ecology and the diets of Ardipithecus, Australopithecus, and early Homo.

    Sayers, Ken; Lovejoy, C Owen


    Beginning with Darwin, some have argued that predation on other vertebrates dates to the earliest stages of hominid evolution, and can explain many uniquely human anatomical and behavioral characters. Other recent workers have focused instead on scavenging, or particular plant foods. Foraging theory suggests that inclusion of any food is influenced by its profitability and distribution within the consumer's habitat. The morphology and likely cognitive abilities of Ardipithecus, Australopithecus, and early Homo suggest that while hunting and scavenging occurred, their profitability generally would have been considerably lower than in extant primates and/or modern human hunter-gatherers. On the other hand, early hominid diet modelers should not focus solely on plant foods, as this overlooks standard functional interpretations of the early hominid dentition, their remarkable demographic success, and the wide range of available food types within their likely day ranges. Any dietary model focusing too narrowly on any one food type or foraging strategy must be viewed with caution. We argue that early hominid diet can best be elucidated by consideration of their entire habitat-specific resource base, and by quantifying the potential profitability and abundance of likely available foods. PMID:25510078

  5. Chimpanzee food preferences, associative learning, and the origins of cooking.

    Beran, Michael J; Hopper, Lydia M; de Waal, Frans B M; Sayers, Ken; Brosnan, Sarah F


    A recent report suggested that chimpanzees demonstrate the cognitive capacities necessary to understand cooking (Warneken & Rosati, 2015). We offer alternate explanations and mechanisms that could account for the behavioral responses of those chimpanzees, without invoking the understanding of cooking as a process. We discuss broader issues surrounding the use of chimpanzees in modeling hominid behavior and understanding aspects of human evolution. PMID:26659967

  6. The evolutionary significance of the Wajak skulls

    Storm, P.


    Ever since their description by Dubois (1920, 1922) the Wajak skulls Java) have played an important role in the discussions on the evolution of modern humans in Australasia. Because of the robust morphology of the skull, Wajak Man was seen as a link between Pleistocene hominids from Java (Solo) and

  7. "Mitochondrial Eve", "Y Chromosome Adam", testosterone, and human evolution.

    Howard, James Michael


    I suggest primate evolution began as a consequence of increased testosterone in males which increased aggression and sexuality, therefore, reproduction and success. With time, negative effects of excessive testosterone reduced spermatogenesis and started a decline of the group. Approximately 30-40 million years ago, the gene DAZ (Deleted in AZoospermia) appeared on the Y chromosome, increased spermatogenesis, and rescued the early primates from extinction. (Note: DAZ is considered by some to specifically, positively affect spermatogenesis; others suggest it has no effect on spermatogenesis.) Hominid evolution continued with increasing testosterone. The advent of increased testosterone in females of Homo erectus (or Homo ergaster) increased the female-to-male body size ratio, and eventually produced another era of excessive testosterone. Excessive testosterone caused a reduction in population size (bottleneck) that produced the "Mitochondrial Eve" (ME) mechanism. (Only certain females continued during the bottleneck to transmit their mitochondrial DNA.) That is, the ME mechanism culminated, again, in excessive testosterone and reduced spermatogenesis in the hominid line. Approximately 50,000 to 200,000 years ago, a "doubling" of the DAZ gene occurred on the Y chromosome in hominid males which rescued the hominid line with increased spermatogenesis in certain males. This produced the "Y Chromosome Adam" event. The doubling of DAZ allowed further increases in testosterone in hominids that resulted in the increased size and development of the brain. Modern humans periodically fluctuate between the positive and negative consequences of increased levels of testosterone, currently identifiable as the secular trend, increased infections, and reduced spermatogenesis. PMID:12449688

  8. Development and progress: advancing towards environmental crisis

    Physical, biological and social evolution is doubtless. One of its first manifestations is the arrival of technique when hominids emerge from pre-hominids. Those first technical developments implied a new relation man/environment that was expressed in three components that appeared successively and pushed each other in time and space like this: dominion over nature, population concentration (urbanism), and population growth. Techniques are to generate three notorious effects on the relation man/nature: 1. Deep intervention on the physical environment: mining and industrial transformation processes; 2. Deep intervention on the biological environment: development of agriculture with a decrease in biodiversity; and 3. Deep intervention on the social environment: going from a pre-modern communitarian world, to the individualism of modernity; and from the agrarian field to the big city. All these technical developments boosted dominion of the technosphere over the ecosphere, which led to the appearance of the Environmental Crisis, whose most notable manifestation is Climatic Change.

  9. Numerical description of selected endo- and ectocranial dimensions in Homo sapiens and the three Homo heidelbergensis: Kabwe, Atapuerca and Petralona.

    Bernhard, M; Schäfer, K; Seidler, H


    Investigation of hominid cranial morphology is of particular importance for those dealing with questions concerning both ontogenetic and phylogenetic aspects in the genus Homo. The present study provides a numerical description of several regions of extant human crania and, in addition, mid-Pleistocene crania, given in distances and angles. This study is seen as a basic preparatory work that is most useful for further investigation on cranial development in hominids. The sample used consisted of 60 recent adult human crania as well as stereolithographic models of three H. heidelbergensis crania: Kabwe, Atapuerca and Petralona. 12 ecto- and 20 endocranial landmarks were selected and 3D-coordinates taken on each cranium using a 3D Polhemus 3Space FASTRAK tracking system. From the resulting data set, 21 ectocranial and 17 endocranial distances were calculated, in addition to 41 angles of the ectocranium and 21 angles of the endocranium; the measurements are presented in tables, serving as a reference database. PMID:12529956

  10. Dental development of the Taung skull from computerized tomography.

    Conroy, G C; Vannier, M W

    Just over 60 years ago, Dart's description and analysis of the Taung child's skull triggered an intellectual revolution about human origins. Recently, several authors have suggested that one of the most significant hominid-like traits of australopithecines, delayed maturation, may not after all be valid. This is a radical departure from Mann's classic study of australopithecine maturation and palaeodemography based on dental eruption patterns. The resolution of this debate has important implications for the history of the biological and social evolution of the human species. In view of the controversies generated by recent studies, and particularly because the Taung skull is the type specimen of Australopithecus africanus, we have investigated the relevant anatomy of the Taung 'child' using computerized tomography. We conclude that the Taung 'child' shows some important dental maturational affinities with great apes, although as Dart noted, other hominid-like features are clearly present. PMID:3116435

  11. The relative cost of bent-hip bent-knee walking is reduced in water.

    Kuliukas, Algis V; Milne, Nick; Fournier, Paul


    The debate about how early hominids walked may be characterised as two competing hypotheses: They moved with a fully upright (FU) gait, like modern humans, or with a bent-hip, bent-knee (BK) gait, like apes. Both have assumed that this bipedalism was almost exclusively on land, in trees or a combination of the two. Recent findings favoured the FU hypothesis by showing that the BK gait is 50-60% more energetically costly than a FU human gait on land. We confirm these findings but show that in water this cost differential is markedly reduced, especially in deeper water, at slower speeds and with greater knee flexion. These data suggest that the controversy about australopithecine locomotion may be eased if it is assumed that wading was a component of their locomotor repertoire and supports the idea that shallow water might have been an environment favourable to the evolution of early forms of "non-optimal" hominid bipedalism. PMID:19853850

  12. Estimation of australopithecine stature from long bones: A.L.288-1 as a test case.

    Geissmann, T


    Regression equations for the estimation of stature from long bones, although derived from modern human populations, are frequently applied to early hominids. In fact, some of these equations have even been recommended or especially created to be applied to Australopithecus remains. In this study, 45 sets of regression and correlation formulae, recurrent in anthropological and medico-legal literature, are applied to long bones of the Pliocene hominid A.L.288-1 ('Lucy'), in order to assess which, if any, could be considered suitable for stature reconstruction in 'gracile' australopithecines. Virtually every method based on regression equations overestimates stature as compared with the estimate based on reconstruction of all the preserved skeletal parts. In addition, most methods failed to give consistent results with data from different limb segments. None of the sets of regression formulae tested here can be recommended as a reliable means of stature estimation in 'gracile' australopithecines. PMID:3108121

  13. A new pelvic fragment from Swartkrans and the relationship between the robust and gracile australopithecines.

    McHenry, H M


    A recently discovered hominid pelvic fragment from Swartkrans (SK 3155) is described in detail with particular reference to the relationship of the two presently recognized forms of australopithecines in South Africa. Results of this examination and metrical analysis indicate that the acetabulum and iliac blade of the early hominids are similar to Homo sapiens except for a unique pattern of traits: a relatively small sacral articular surface, a relatively small acetabulum, a relatively large iliac fossa, and wide lateral splaying of the iliac blades. The new Swartkrans fossil expresses these traits more strongly than does the gracile australopithecine (Sts 14) and is therefore somewhat less similar to Homo sapiens but it is very unlike any pongid. PMID:810037

  14. Primate facial allometry and interpretations of australopithecine variation.

    Corruccini, R S; Ciochon, R L


    Pilbeam and Gould have discussed African Plio-Pleistocene hominid evolution in the context of allometry (size-dependent morphological change). These authors demonstrate that some general aspects of australopithecine morphology (tooth, brain and body size) support the hypothesis that certain early African hominids were merely scaled variations of each other at different sizes. They also speculate that the methods applied to these very broad anatomical categories can be extended to more specific and detailed traits, especially in the face and cranium. Such traits underlie most taxonomic and phylogenetic discussions of the early African Hominidae, so it is useful to follow Pilbeam and Gould's lead, as we do here, and investigate the structural differences in the australopithecine face and cranimum in a quantificiable fashion. PMID:121762

  15. A new interdisciplinary approach to the study of the origins of traditional polyphony

    Jordania Joseph


    Full Text Available The article discusses a new model of the origins of choral singing in the context of human evolutionary history. Hominid interaction with predators is seen as a crucial force in the evolution of human morphology and behaviour. Group singing and dancing, with body painting and the use of masks, are perceived as critical elements of the strategy to deter predators and to put hominids into an altered state of consciousness. In this state, humans do not feel fear and pain and are ready to sacrifice their lives for the common goal. This psychological condition is still important to many human group activities, particularly in religion and the military. The mosaic distribution of polyphonic traditions is discussed in the context of the origins of language and articulated speech.

  16. Effective Population Size Is Positively Correlated with Levels of Adaptive Divergence among Annual Sunflowers

    Strasburg, Jared L.; Kane, Nolan C.; Raduski, Andrew R.; Bonin, Aurélie; Michelmore, Richard; Rieseberg, Loren H.


    The role of adaptation in the divergence of lineages has long been a central question in evolutionary biology, and as multilocus sequence data sets have become available for a wide range of taxa, empirical estimates of levels of adaptive molecular evolution are increasingly common. Estimates vary widely among taxa, with high levels of adaptive evolution in Drosophila, bacteria, and viruses but very little evidence of widespread adaptive evolution in hominids. Although estimates in plants are ...

  17. The evolution of shelter: ecology and ethology of chimpanzee nest building

    Stewart, Fiona Anne


    Human beings of all cultures build some form of shelter, and the global distribution of Homo sapiens depends on this basic trait. All great apes (chimpanzee, bonobo, gorilla, and orangutan) build analogous structures (called nests or beds) at least once a day throughout their adult lives, which suggests that this elementary technology was present before the hominid lines separated. This thesis investigates the variability and function of specifically wild chimpanzee shelters. I compared ch...

  18. The Modes of Evolutionary Emergence of Primal and Late Pandemic Influenza Virus Strains from Viral Reservoir in Animals: An Interdisciplinary Analysis


    Based on a wealth of recent findings, in conjunction with earliest chronologies pertaining to evolutionary emergences of ancestral RNA viruses, ducks, Influenzavirus A (assumingly within ducks), and hominids, as well as to the initial domestication of mallard duck (Anas platyrhynchos), jungle fowl (Gallus gallus), wild turkey (Meleagris gallopavo), wild boar (Sus scrofa), and wild horse (Equus ferus), presumed genesis modes of primordial pandemic influenza strains have multidisciplinarily bee...

  19. Le rôle écologique des bonobos : service écologique de dispersion de graine en forêt du Congo

    Beaune, David


    Bonobos (Pan paniscus) are threatened with extinction. They are the largest primates, and the only apes (except human), of the southern bank of the Congo Basin. Along with chimpanzees, they are our closest living relatives and are studied by anthropologists to include/understand our hominid origins; but what about their functional role in the forest? Would their disappearance have serious consequences for forest ecology? Answering this question is the aim of this new project, with several yea...

  20. Evolutionary History of a Brain Controlling Brain Size

    Natalay Kouprina; Adam Pavlicek; Mochida, Ganeshwaran H.; Gregory Solomon; William Gersch; Young-Ho Yoon; Randall Collura; Maryellen Ruvolo; J Carl Barrett; C Geoffrey Woods; Walsh, Christopher A.; Jerzy Jurka; Vladimir Larionov


    Primary microcephaly (MCPH) is a neurodevelopmental disorder characterized by global reduction in cerebral cortical volume. The microcephalic brain has a volume comparable to that of early hominids, raising the possibility that some MCPH genes may have been evolutionary targets in the expansion of the cerebral cortex in mammals and especially primates. Mutations in ASPM, which encodes the human homologue of a fly protein essential for spindle function, are the most common known cause of MCPH....

  1. Evolutionary Psychology, Adaptation, and the Evoltion of Lanaguage: Is there a Need for Comparsion?

    Krause, Mark A.


    A general assumption held by evolutionary psychologists is that a reference point for examining the origins and evolution of human psychological adaptations exists within a time range beginning roughly two million years ago. Scenarios for explaining the evolution of human psychological processes often allude to possible election pressures encountered by hominids during this time. unfortunately, comparative psychology and ethology are relatively absent from much current evolutionary psychologi...

  2. SP8 Sequencing Extinct Genomes

    Poinar, H.


    Nucleic acids, which hold clues to the evolution of various animal and hominid taxa, are comparatively weak molecules from other cellular debris, and thus evolutionary biologists are in essence time trapped. Fortunately, DNA and protein fragments do exist in fossil remains beyond what theoretical experimentation would suggest. Sequestering of DNA molecules in humic or Maillard-like complexes likely represents a rich source of DNA molecules from the past, which have yet to be tapped. These mol...

  3. The robust australopithecine face: a morphogenetic perspective.

    McCollum, M A


    The robust australopithecines were a side branch of human evolution. They share a number of unique craniodental features that suggest their monophyletic origin. However, virtually all of these traits appear to reflect a singular pattern of nasomaxillary modeling derived from their unusual dental proportions. Therefore, recent cladistic analyses have not resolved the phylogenetic history of these early hominids. Efforts to increase cladistic resolution by defining traits at greater levels of anatomical detail have instead introduced substantial phyletic error. PMID:10195892

  4. Australopithecine endocast (Taung specimen, 1924): a new volume determination.

    Holloway, R L


    A redetermination of endocranial volume of the original 1924 Taung australopithecine described by Dart indicates a volume of 405 cubic centimeters, rather than the 525 cubic centimeters published earlier. The adult volume is estimated to have been 440 cubic centimeters. This value, plus other redeterminations of australopithecine endocasts, lowers the average to 442 cubic centimeters, and increase the likelihood of statistically significant differences from both robust australopithecines and the Olduvai Gorge hominid No. 7. PMID:5441027


    Sayers, Ken; Lovejoy, C. Owen


    Beginning with Darwin, some have argued that predation on other vertebrates dates to the earliest stages of hominid evolution, and can explain many uniquely human anatomical and behavioral characters. Other recent workers have focused instead on scavenging, or particular plant foods. Foraging theory suggests that inclusion of any food is influenced by its profitability and distribution within the consumer’s habitat. The morphology and likely cognitive abilities of Ardipithecus, Australopithec...

  6. Phylogeny of early Australopithecus: new fossil evidence from the Woranso-Mille (central Afar, Ethiopia).

    Haile-Selassie, Yohannes


    The earliest evidence of Australopithecus goes back to ca 4.2 Ma with the first recorded appearance of Australopithecus 'anamensis' at Kanapoi, Kenya. Australopithecus afarensis is well documented between 3.6 and 3.0 Ma mainly from deposits at Laetoli (Tanzania) and Hadar (Ethiopia). The phylogenetic relationship of these two 'species' is hypothesized as ancestor-descendant. However, the lack of fossil evidence from the time between 3.6 and 3.9 Ma has been one of its weakest points. Recent fieldwork in the Woranso-Mille study area in the Afar region of Ethiopia has yielded fossil hominids dated between 3.6 and 3.8 Ma. These new fossils play a significant role in testing the proposed relationship between Au. anamensis and Au. afarensis. The Woranso-Mille hominids (3.6-3.8 Ma) show a mosaic of primitive, predominantly Au. anamensis-like, and some derived (Au. afarensis-like) dentognathic features. Furthermore, they show that, as currently known, there are no discrete and functionally significant anatomical differences between Au. anamensis and Au. afarensis. Based on the currently available evidence, it appears that there is no compelling evidence to falsify the hypothesis of 'chronospecies pair' or ancestor-descendant relationship between Au. anamensis and Au. afarensis. Most importantly, however, the temporally and morphologically intermediate Woranso-Mille hominids indicate that the species names Au. afarensis and Au. anamensis do not refer to two real species, but rather to earlier and later representatives of a single phyletically evolving lineage. However, if retaining these two names is necessary for communication purposes, the Woranso-Mille hominids are best referred to as Au. anamensis based on new dentognathic evidence. PMID:20855306

  7. Inference of Gorilla Demographic and Selective History from Whole-Genome Sequence Data

    McManus, Kimberly F; Kelley, Joanna L.; Song, Shiya; Veeramah, Krishna R; Woerner, August E.; Stevison, Laurie S.; Ryder, Oliver A.; Ape Genome Project, Great; Kidd, Jeffrey M.; Wall, Jeffrey D.; Bustamante, Carlos D.; Hammer, Michael F.


    Although population-level genomic sequence data have been gathered extensively for humans, similar data from our closest living relatives are just beginning to emerge. Examination of genomic variation within great apes offers many opportunities to increase our understanding of the forces that have differentially shaped the evolutionary history of hominid taxa. Here, we expand upon the work of the Great Ape Genome Project by analyzing medium to high coverage whole-genome sequences from 14 west...

  8. Culture, Urbanism and Changing Human Biology

    Schell, L M


    Anthropologists have long known that human activity driven by culture changes the environment. This is apparent in the archaeological record and through the study of the modern environment. Perhaps the largest change since the paleolithic era is the organization of human populations in cities. New environments can reshape human biology through evolution as shown by the evolution of the hominid lineage. Evolution is not the only process capable of reshaping our biology. Some changes in our hum...

  9. The expression of asymmetry in hand bones from the medieval cemetery at Écija, Spain

    Cashmore, Lisa; Zakrzewski, Sonia R.


    The unique nature of ‘handedness’ in modern humans poses questions about the development of this trait in both extinct hominid species and archaeological populations. An examination of the expression of hand preference in skeletal material is required to answer such questions. The main focus of previous research on asymmetry and hand preference has been on the bones of the upper limb, rather than those of the hand. This study addresses this issue by exploring the expression of asymmetry in th...

  10. Chimpanzee hand preference for throwing and infant cradling:implications for the origin of human handedness

    Hopkins, William D.; Bard, Kim A.; Jones, A.; Bales, S. L.


    Calvin (i983) has hypothesized that the neurophysiological, perceptual, and cognitive demands of throwing may have served as important evolutionary precursors to a variety of traits( e.g., handedness, tool use, and language processing) in early hominids. Eighty-eight percent of humans throw with their right hands (Healey, Liederman, and Geschwind I986), and Calvin has argued that this right-handed throwing evolved as a result of a left-hemisphere specialization for planned sequential movement...