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Sample records for anomodonts tetrapoda therapsida

  1. Global taxonomic diversity of anomodonts (tetrapoda, therapsida and the terrestrial rock record across the Permian-Triassic boundary.

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    Jörg Fröbisch

    Full Text Available The end-Permian biotic crisis (~252.5 Ma represents the most severe extinction event in Earth's history. This paper investigates diversity patterns in Anomodontia, an extinct group of therapsid synapsids ('mammal-like reptiles', through time and in particular across this event. As herbivores and the dominant terrestrial tetrapods of their time, anomodonts play a central role in assessing the impact of the end-Permian extinction on terrestrial ecosystems. Taxonomic diversity analysis reveals that anomodonts experienced three distinct phases of diversification interrupted by the same number of extinctions, i.e. an end-Guadalupian, an end-Permian, and a mid-Triassic extinction. A positive correlation between the number of taxa and the number of formations per time interval shows that anomodont diversity is biased by the Permian-Triassic terrestrial rock record. Normalized diversity curves indicate that anomodont richness continuously declines from the Middle Permian to the Late Triassic, but also reveals all three extinction events. Taxonomic rates (origination and extinction indicate that the end-Guadalupian and end-Permian extinctions were driven by increased rates of extinction as well as low origination rates. However, this pattern is not evident at the final decline of anomodont diversity during the Middle Triassic. Therefore, it remains unclear whether the Middle Triassic extinction represents a gradual or abrupt event that is unique to anomodonts or more common among terrestrial tetrapods. The end-Permian extinction represents the most distinct event in terms of decline in anomodont richness and turnover rates.

  2. Composition and similarity of global anomodont-bearing tetrapod faunas

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    Fröbisch, Jörg

    2009-08-01

    Anomodont synapsids represent the dominant herbivores of Permian and Triassic terrestrial vertebrate ecosystems. Their taxonomic diversity and morphological disparity in combination with their cosmopolitan distribution makes them an ideal study object for macroevolutionary patterns across the most devastating extinction event in earth history. This study provides a thorough review of anomodont-bearing tetrapod faunas to form the basis for a faunal similarity analysis and future studies of anomodont diversity. The stratigraphic correlation and composition of all known anomodont assemblages is revisited, including a discussion of the validity of the globally distributed anomodont species. The similarity analysis of anomodont faunas is performed on the basis of presence-absence data of anomodont taxa, using explorative methods such as cluster analysis (UPGMA) and non-metric multidimensional scaling (NMDS). The recovered faunal groupings indicate a common biostratigraphic age and furthermore reflect biogeographic patterns. Even though endemism and faunal provinciality was a constant element in anomodont faunas of the Permian and Triassic, the available evidence indicates that the end-Permian extinction resulted in a distinct uniformity that was unique to Early Triassic anomodont faunas. This is in particular characterized by the global distribution and overwhelming abundance of the disaster taxon Lystrosaurus. In contrast, cosmopolitan anomodonts also existed in the Late Permian (e.g., Diictodon) and Middle Triassic (e.g., Shansiodon), but those taxa coexisted with endemic faunal elements rather than dominated the fauna as Lystrosaurus did.

  3. One tree to link them all: a phylogenetic dataset for the European tetrapoda.

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    Roquet, Cristina; Lavergne, Sébastien; Thuiller, Wilfried

    2014-08-08

    Since the ever-increasing availability of phylogenetic informative data, the last decade has seen an upsurge of ecological studies incorporating information on evolutionary relationships among species. However, detailed species-level phylogenies are still lacking for many large groups and regions, which are necessary for comprehensive large-scale eco-phylogenetic analyses. Here, we provide a dataset of 100 dated phylogenetic trees for all European tetrapods based on a mixture of supermatrix and supertree approaches. Phylogenetic inference was performed separately for each of the main Tetrapoda groups of Europe except mammals (i.e. amphibians, birds, squamates and turtles) by means of maximum likelihood (ML) analyses of supermatrix applying a tree constraint at the family (amphibians and squamates) or order (birds and turtles) levels based on consensus knowledge. For each group, we inferred 100 ML trees to be able to provide a phylogenetic dataset that accounts for phylogenetic uncertainty, and assessed node support with bootstrap analyses. Each tree was dated using penalized-likelihood and fossil calibration. The trees obtained were well-supported by existing knowledge and previous phylogenetic studies. For mammals, we modified the most complete supertree dataset available on the literature to include a recent update of the Carnivora clade. As a final step, we merged the phylogenetic trees of all groups to obtain a set of 100 phylogenetic trees for all European Tetrapoda species for which data was available (91%). We provide this phylogenetic dataset (100 chronograms) for the purpose of comparative analyses, macro-ecological or community ecology studies aiming to incorporate phylogenetic information while accounting for phylogenetic uncertainty.

  4. Growth increments in teeth of Diictodon (Therapsida

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    J. Francis Thackeray

    1991-09-01

    Full Text Available Growth increments circa 0.02 mm in width have been observed in sectioned tusks of Diictodon from the Late Permian lower Beaufort succession of the South African Karoo, dated between about 260 and 245 million years ago. Mean growth increments show a decline from relatively high values in the Tropidostoma/Endothiodon Assemblage Zone, to lower values in the Aulacephalodon/Cistecephaluszone, declining still further in the Dicynodon lacerficeps/Whaitsia zone at the end of the Permian. These changes coincide with gradual changes in carbon isotope ratios measured from Diictodon tooth apatite. It is suggested that the decline in growth increments is related to environmental changes associated with a decline in primary production which contributed to the decline in abundance and ultimate extinction of Diictodon.

  5. Evolutionary development of the neurocranium in Dissorophoidea (Tetrapoda: Temnospondyli), an integrative approach.

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    Maddin, Hillary C; Reisz, Robert R; Anderson, Jason S

    2010-01-01

    Ontogenetic data can play a prominent role in addressing questions in tetrapod evolution, but such evidence from the fossil record is often incompletely considered because it is limited to initiation of ossification, or allometric changes with increasing size. In the present study, specimens of a new species of an archaic amphibian (280 Myr old), Acheloma n. sp., a member of the temnospondyl superfamily Dissorophoidea and the sister group to Amphibamidae, which is thought to include at least two of our modern amphibian clades, anurans and caudatans (Batrachia), provides us with new developmental data. We identify five ontogenetic events, enabling us to construct a partial ontogenetic trajectory (integration of developmental and transformation sequence data) related to the relative timing of completion of neurocranial structures. Comparison of the adult amphibamid morphology with this partial ontogeny identifies a heterochronic event that occurred within the neurocranium at some point in time between the two taxa, which is consistent with the predictions of miniaturization in amphibamids, providing the first insights into the influence of miniaturization on the neurocranium in a fossil tetrapod group. This study refines hypotheses of large-scale evolutionary trends within Dissorophoidea that may have facilitated the radiation of amphibamids and, projected forward, the origin of the generalized batrachian skull. Most importantly, this study highlights the importance of integrating developmental and transformation sequence data, instead of onset of ossification alone, into investigations of major events in tetrapod evolution using evidence provided by the fossil record, and highlights the value of even highly incomplete growth series comprised of relatively late-stage individuals.

  6. Evidências de Anomalias Ósseas em Stahleckeria potens Huene, 1935 (Therapsida, Anomodontia.

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    Cibele Schwanke

    2007-07-01

    Full Text Available Os dicinodontes representam um grupo de tetrápodes herbívoros amplamente registrado em rochas sedimentares do Permiano Superior eTriássico. Uma das espécies mais instigantes é Stahleckeria potens Huene 1935, uma forma de porte avantajado cujos fósseis, até o momento, foram registrados unicamente em sedimentos mesotriássicos da Formação Santa Maria (Bacia do Paraná, Brasil. Nos últimos anos, novos materiais atribuídos a S. potens têm sido identificadosaumentando consideravelmente o conhecimento da morfologia da espécie. A análise comparativa de dois fêmures esquerdos depositados no Museu de Ciências da Terra (DNPM/RJ evidenciam anormalidadesósseas significativas (DGM 155-R e DGM- 399-R, aqui apresentadas preliminarmente e sugestivamente associadas a patologias. O espécime DGM 399- R caracteriza-se por apresentar uma acentuada depressão na região da epífise distal. Esta depressão localiza-se na face anterior do osso, lateralmente posicionada e possui um formato grosseiramente circular, criando uma espécie de platô nesta região,acompanhada por um leve deslocamento ósseo. Em oposição, na face posterior do osso, há um pequeno sulco de formato claramente semicircular, onde são visualizadas cerca de sete pequenas perfurações rasas, que demonstram certa regularidade, porémsem formato definido. Tais feições sugerem que as alterações ósseas presentes no espécime possam estar associadas a lesões ou traumas decorrentes de diversos fatores. Embora não observado claramente,há evidências de cicatrização local, hipótese que vem sendo analisada mais detalhadamente a partir da utilização de técnicas de maior precisão e resolução, como tomografia computadorizada e microscopia eletrônica de varredura. A ocorrência de uma extensaregião marcada pela presença de estrutura óssea irregular, diferente do padrão normal linear, pode ser interpretada como decorrente de remodelação do periósteo, resultante de um processo inflamatório,provavelmente associado às depressões descritas, o que reforça a idéia de que tais anomalias ósseas tenham sido ocasionadas durante a vida do animal. O segundo espécime (DGM 155-R apresenta umaextensa área claramente desgastada, formando epífise proximal e se prolonga até o início da diáfise, aparentemente resultante da fossildiagênese. Uma análise mais detalhada desta depressão nos permite observar além das perdas tafonômicas, estruturasque sugerem a existência de um remodelamento ósseo, que pode ter atingindo grande parte da região cortical do osso. Em áreas associadas a esta egião, encontram-se indícios de remodelamento doperiósteo, caracterizado por estrutura óssea irregular, sugerindo a existência de algum processo traumático ou infeccioso. Dessa forma, é possível inferir que esta alteração esteja associada a um processo de inflamação óssea gerado por infecções, distensões musculares ou fraturas em outros membros ou ossos da mesma pata, que possam ter afetado a postura e a locomoção do animal. Assim, considera-se que odesgaste pós-morte local tenha sido facilitado pela presença de uma estrutura mais fragilizada do osso remodelado nesta região.

  7. Cranial Bosses of Choerosaurus dejageri (Therapsida, Therocephalia): Earliest Evidence of Cranial Display Structures in Eutheriodonts.

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    Benoit, Julien; Manger, Paul R; Fernandez, Vincent; Rubidge, Bruce S

    2016-01-01

    Choerosaurus dejageri, a non-mammalian eutheriodont therapsid from the South African late Permian (~259 Ma), has conspicuous hemispheric cranial bosses on the maxilla and the mandible. These bosses, the earliest of this nature in a eutheriodont, potentially make C. dejageri a key species for understanding the evolutionary origins of sexually selective behaviours (intraspecific competition, ritualized sexual and intimidation displays) associated with cranial outgrowths at the root of the clade that eventually led to extant mammals. Comparison with the tapinocephalid dinocephalian Moschops capensis, a therapsid in which head butting is strongly supported, shows that the delicate structure of the cranial bosses and the gracile structure of the skull of Choerosaurus would be more suitable for display and low energy combat than vigorous head butting. Thus, despite the fact that Choerosaurus is represented by only one skull (which makes it impossible to address the question of sexual dimorphism), its cranial bosses are better interpreted as structures involved in intraspecific selection, i.e. low-energy fighting or display. Display structures, such as enlarged canines and cranial bosses, are widespread among basal therapsid clades and are also present in the putative basal therapsid Tetraceratops insignis. This suggests that sexual selection may have played a more important role in the distant origin and evolution of mammals earlier than previously thought. Sexual selection may explain the subsequent independent evolution of cranial outgrowths and pachyostosis in different therapsid lineages (Biarmosuchia, Dinocephalia, Gorgonopsia and Dicynodontia).

  8. Cranial Bosses of Choerosaurus dejageri (Therapsida, Therocephalia: Earliest Evidence of Cranial Display Structures in Eutheriodonts.

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    Julien Benoit

    Full Text Available Choerosaurus dejageri, a non-mammalian eutheriodont therapsid from the South African late Permian (~259 Ma, has conspicuous hemispheric cranial bosses on the maxilla and the mandible. These bosses, the earliest of this nature in a eutheriodont, potentially make C. dejageri a key species for understanding the evolutionary origins of sexually selective behaviours (intraspecific competition, ritualized sexual and intimidation displays associated with cranial outgrowths at the root of the clade that eventually led to extant mammals. Comparison with the tapinocephalid dinocephalian Moschops capensis, a therapsid in which head butting is strongly supported, shows that the delicate structure of the cranial bosses and the gracile structure of the skull of Choerosaurus would be more suitable for display and low energy combat than vigorous head butting. Thus, despite the fact that Choerosaurus is represented by only one skull (which makes it impossible to address the question of sexual dimorphism, its cranial bosses are better interpreted as structures involved in intraspecific selection, i.e. low-energy fighting or display. Display structures, such as enlarged canines and cranial bosses, are widespread among basal therapsid clades and are also present in the putative basal therapsid Tetraceratops insignis. This suggests that sexual selection may have played a more important role in the distant origin and evolution of mammals earlier than previously thought. Sexual selection may explain the subsequent independent evolution of cranial outgrowths and pachyostosis in different therapsid lineages (Biarmosuchia, Dinocephalia, Gorgonopsia and Dicynodontia.

  9. Masticatory jaw movement of Exaeretodon argentinus (Therapsida: Cynodontia inferred from its dental microwear.

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    Tai Kubo

    Full Text Available Dental microwear of four postcanine teeth of Exaeretodon argentinus was analyzed using both two dimensional (2D and three dimensional (3D methods to infer their masticatory jaw movements. Results of both methods were congruent, showing that linear microwear features (scratches were well aligned and mostly directed to the antero-posterior direction in all four teeth examined. These findings support the palinal masticatory jaw movement, which was inferred in previous studies based on the observation of gross morphology of wear facets. In contrast, the lack of detection of lateral scratches confirmed the absence of the lateral jaw movement that was also proposed by a previous study. Considering previous microwear studies on cynodonts, palinal jaw movements observed in Exaeretodon evolved within cynognathian cynodonts from the fully orthal jaw movement of its basal member. Although there are currently only three studies of dental microwear of non-mammalian cynodonts including the present study, microwear analysis is a useful tool for the reconstruction of masticatory jaw movement and its future application to various cynodonts will shed light on the evolutionary process of jaw movement towards the mammalian condition in more detail.

  10. Synchrotron scanning reveals the palaeoneurology of the head-butting Moschops capensis (Therapsida, Dinocephalia

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    Julien Benoit

    2017-08-01

    Full Text Available Dinocephalian therapsids are renowned for their massive, pachyostotic and ornamented skulls adapted for head-to-head fighting during intraspecific combat. Synchrotron scanning of the tapinocephalid Moschops capensis reveals, for the first time, numerous anatomical adaptations of the central nervous system related to this combative behaviour. Many neural structures (such as the brain, inner ear and ophthalmic branch of the trigeminal nerve were completely enclosed and protected by bones, which is unusual for non-mammaliaform therapsids. The nearly complete ossification of the braincase enables precise determination of the brain cavity volume and encephalization quotient, which appears greater than expected for such a large and early herbivore. The practice of head butting is often associated with complex social behaviours and gregariousness in extant species, which are known to influence brain size evolution. Additionally, the plane of the lateral (horizontal semicircular canal of the bony labyrinth is oriented nearly vertically if the skull is held horizontally, which suggests that the natural position of the head was inclined about 60–65°to the horizontal. This is consistent with the fighting position inferred from osteology, as well as ground-level browsing. Finally, the unusually large parietal tube may have been filled with thick conjunctive tissue to protect the delicate pineal eye from injury sustained during head butting.

  11. Origin of secretin receptor precedes the advent of tetrapoda: evidence on the separated origins of secretin and orexin.

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    Janice K V Tam

    Full Text Available At present, secretin and its receptor have only been identified in mammals, and the origin of this ligand-receptor pair in early vertebrates is unclear. In addition, the elusive similarities of secretin and orexin in terms of both structures and functions suggest a common ancestral origin early in the vertebrate lineage. In this article, with the cloning and functional characterization of secretin receptors from lungfish and X. laevis as well as frog (X. laevis and Rana rugulosa secretins, we provide evidence that the secretin ligand-receptor pair has already diverged and become highly specific by the emergence of tetrapods. The secretin receptor-like sequence cloned from lungfish indicates that the secretin receptor was descended from a VPAC-like receptor prior the advent of sarcopterygians. To clarify the controversial relationship of secretin and orexin, orexin type-2 receptor was cloned from X. laevis. We demonstrated that, in frog, secretin and orexin could activate their mutual receptors, indicating their coordinated complementary role in mediating physiological processes in non-mammalian vertebrates. However, among the peptides in the secretin/glucagon superfamily, secretin was found to be the only peptide that could activate the orexin receptor. We therefore hypothesize that secretin and orexin are of different ancestral origins early in the vertebrate lineage.

  12. \\"Descrição morfológica e posição filogenética de um anuro novo (Lissamphibia, Tetrapoda) do Cretáceo Superior Continental do Brasil (Formação Adamantina, Bacia Bauru) do Município de Marília, (SP)\\"

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    Alberto Barbosa de Carvalho

    2006-01-01

    O registro fossilífero de anuros mesozóicos é raro na maioria das bacias sedimentares do mundo. Na América do Sul, esses registros são ainda mais escassos, principalmente no Brasil. Das ocorrências deste grupo nas bacias sedimentares brasileiras, são conhecidos Arariphrynus placidoi Leal e Brito 2006, do Cretáceo Inferior da Bacia do Araripe, e Baurubatrachus pricei Báez e Peri, 1989, Cretáceo Superior da Bacia Bauru. A Bacia Bauru (sensu Fernandes & Coimbra, 1996) teve o início de sua depos...

  13. Journal of Biosciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Laboratório de Zoologia de Vertebrados (Tetrapoda) (LAZOVERTE), DZ, IBRAG, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524 – Maracanã –CEP: 20550-013 –Rio de Janeiro, RJ, Brazil; Departament de Biologia Animal (Vertebrats), Universitat de Barcelona, Diagonal, 645( 08028 Barcelona, ...

  14. Phylogeny mandalas for illustrating the Tree of Life.

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    Hasegawa, Masami

    2017-12-01

    A circular phylogeny with photos or drawings of species is named a phylogeny mandala. This is one of the ways for illustrating the Tree of Life, and is suitable to show visually how the biodiversity has developed in the course of evolution as clarified by the molecular phylogenetics. To demonstrate the recent progress of molecular phylogenetics, six phylogeny mandalas for various taxonomic groups of life were presented; i.e., (1) Eukaryota, (2) Metazoa, (3) Hexapoda, (4) Tetrapoda, (5) Eutheria, and (6) Primates. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Prevalence and intensity of pentastomid infection in two species of snakes from northeastern Brazil

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    WO Almeida

    Full Text Available This study aimed to evaluate the infection rates of snakes by pentastomids in the semi-arid region of Brazil. Fifteen snakes (four Micrurus ibiboboca (Merrem, 1820 and eleven Philodryas nattereri Steindachner, 1870 were collected between January and April of 2005, in the municipality of Crato (07° 14' S and 39° 24' W, State of Ceará, Brazil. Laboratorial analysis of the respiratory tracts of the sampled snakes indicated differences in host infection rates: four individuals of P. nattereri (36.4% were infected by Cephalobaena tetrapoda Heymons, 1922 (mean infection intensity 1.5 ± 0.28, 1-2 and three specimens (27.3% by Raillietiella furcocerca (Diesing, 1863 (2.3 ± 1.32, 1-5. Only one individual of M. ibiboboca (25% was infected by a non-identified species of Raillietiella sp. These are the first data on pentastomid infection in snakes in Northeastern Brazil and both snake species comprise new host records for the pentastomids. The results also indicate that the generalist parasites C. tetrapoda and R. furcocerca share their definitive hosts.

  16. Heterochronical patterns of evolution in the transitional stages of vertebrate classes.

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    Schad, W

    1993-12-01

    Transitional forms of the recent classes of vertebrates are only known in paleontology. The well described examples are: Eusthenopteron foordi (Crossopterygii), Ichthyostega and Acanthostega (Labyrinthodontia) between Osteichthyes and Amphibia, Seymouria baylorensis (Amphibiosaria) between Amphibia and Reptilia, Archaeopteryx lithographica (Archaeornithes) between Reptilia and Aves, and the mammal-like reptiles Pelycosauria, Therapsida and Cynodontia between Reptilia and Aves, and the description of their phylogenetical heterochronies in terms of peramorphosis and paedomorphosis shows the progressive role of the motorial, especially the locomotorial organ systems and their functions in comparison with the retarded evolution of the axial system, especially the skull and central nervous system. The evolution of the Hominidae shows the same rule. The evaluation of these transitional forms in their fossil context reveals them as inhabitants of biotopes situated in the border areas of coastal and shore landscapes of marine, brackish or fresh water. These biotopes have obviously favoured the innovations on the high taxonimic level of macro-evolutionary characteristics.

  17. The origins of the cochlea and impedance matching hearing in synapsids

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    Michael Laass

    2016-06-01

    Full Text Available The origin of tympanic hearing in early synapsids is still controversial, because little is known about their inner ear and the function of their sound conducting apparatus. Here I describe the earliest known tympanic ear in the synapsid lineage, the ear of Pristerodon (Therapsida, Anomodontia from the Late Permian of South Africa, which was virtually reconstructed from neutron tomographic data. Although Pristerodon is not a direct ancestor of mammals, its inner ear with distinctive cochlear cavity represents a connecting link between the primitive therapsid inner ear and the mammalian inner ear. The anatomy of the sound conducting apparatus of Pristerodon and the increased sound pressure transformer ratio points to a sensitivity to airborne sound. Furthermore, the origins of the cochlea and impedance matching hearing in synapsids coincided with the loss of contact between head and substrate, which already took place at least in Late Permian therapsids even before the postdentary bones became detached from the mandible.

  18. The ultrastructure of the spermatozoon of the lizard Iguana iguana (Reptilia, Squamata, Iguanidae) and the variability of sperm morphology among iguanian lizards

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    Vieira, Gustavo H C; Colli, Guarino R; Báo, Sônia N

    2004-01-01

    The spermatozoon of Iguana iguana is filiform and resembles that of other iguanian lizards, being most similar to Tropidurus. All sperm synapomorphies of Tetrapoda, Amniota and Squamata are present in the sperm of Iguana iguana. By reconstructing the evolution of 30 sperm characters we identified a novel synapomorphy of Iguania: the presence of a well-developed acrosomal ridge at the level of the epinuclear lucent zone. Because of the poor topological resolution among iguanian clades we could not discount the possibility of convergence or neutral selection as determinant of the variability in characteristics of the sperm cell. In agreement with previous studies, we identified heterogeneous rates of evolution among the three main regions of the sperm cell, namely the head, midpiece and tail. PMID:15198687

  19. Nocturnality in synapsids predates the origin of mammals by over 100 million years.

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    Angielczyk, K D; Schmitz, L

    2014-10-22

    Nocturnality is widespread among extant mammals and often considered the ancestral behavioural pattern for all mammals. However, mammals are nested within a larger clade, Synapsida, and non-mammalian synapsids comprise a rich phylogenetic, morphological and ecological diversity. Even though non-mammalian synapsids potentially could elucidate the early evolution of diel activity patterns and enrich the understanding of synapsid palaeobiology, data on their diel activity are currently unavailable. Using scleral ring and orbit dimensions, we demonstrate that nocturnal activity was not an innovation unique to mammals but a character that appeared much earlier in synapsid history, possibly several times independently. The 24 Carboniferous to Jurassic non-mammalian synapsid species in our sample featured eye morphologies consistent with all major diel activity patterns, with examples of nocturnality as old as the Late Carboniferous (ca 300 Ma). Carnivores such as Sphenacodon ferox and Dimetrodon milleri, but also the herbivorous cynodont Tritylodon longaevus were likely nocturnal, whereas most of the anomodont herbivores are reconstructed as diurnal. Recognizing the complexity of diel activity patterns in non-mammalian synapsids is an important step towards a more nuanced picture of the evolutionary history of behaviour in the synapsid clade. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  20. An early geikiid dicynodont from the Tropidostoma Assemblage Zone (late Permian of South Africa

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    Christian F. Kammerer

    2017-01-01

    Full Text Available Based on specimens previously identified as Tropidostoma, a new taxon of dicynodont (Bulbasaurus phylloxyron gen. et sp. nov. from the Karoo Basin of South Africa is described. Bulbasaurus is a medium-sized dicynodont (maximum dorsal skull length 16.0 cm restricted to the Tropidostoma Assemblage Zone (early Lopingian of the Beaufort Group. Bulbasaurus can be distinguished from Tropidostoma by an array of characters including the presence of a tall, sharp premaxillary ridge, large, rugose, nearly-confluent nasal bosses, a nasofrontal ridge, massive tusks, robust pterygoids, prominently twisted subtemporal bar, and absence of a distinct postfrontal. Inclusion of Bulbasaurus in a phylogenetic analysis of anomodont therapsids recovers it as a member of Geikiidae, a clade of otherwise later Permian dicynodonts such as Aulacephalodon and Pelanomodon. Bulbasaurus exhibits many of the characters typical of adult Aulacephalodon, but at substantially smaller skull size (these characters are absent in comparably-sized Aulacephalodon juveniles, suggesting that the evolution of typical geikiid morphology preceded gigantism in the clade. Bulbasaurus is the earliest known geikiid and the only member of the group known from the Tropidostoma Assemblage Zone; discovery of this taxon shortens a perplexing ghost lineage and indicates that abundant clades from the later Permian of South Africa (e.g., Geikiidae, Dicynodontoidea may have originated as rare components of earlier Karoo assemblage zones.

  1. The sixth sense in mammalian forerunners: Variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids

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    Julien Benoit

    2016-12-01

    Full Text Available In some extant ectotherms, the third eye (or pineal eye is a photosensitive organ located in the parietal foramen on the midline of the skull roof. The pineal eye sends information regarding exposure to sunlight to the pineal complex, a region of the brain devoted to the regulation of body temperature, reproductive synchrony, and biological rhythms. The parietal foramen is absent in mammals but present in most of the closest extinct relatives of mammals, the Therapsida. A broad ranging survey of the occurrence and size of the parietal foramen in different South African therapsid taxa demonstrates that through time the parietal foramen tends, in a convergent manner, to become smaller and is absent more frequently in eutherocephalians (Akidnognathiidae, Whaitsiidae, and Baurioidea and non-mammaliaform eucynodonts. Among the latter, the Probainognathia, the lineage leading to mammaliaforms, are the only one to achieve the complete loss of the parietal foramen. These results suggest a gradual and convergent loss of the photoreceptive function of the pineal organ and degeneration of the third eye. Given the role of the pineal organ to achieve fine-tuned thermoregulation in ectotherms (i.e., “cold-blooded” vertebrates, the gradual loss of the parietal foramen through time in the Karoo stratigraphic succession may be correlated with the transition from a mesothermic metabolism to a high metabolic rate (endothermy in mammalian ancestry. The appearance in the eye of melanopsin-containing retinal ganglion cells replacing the photoreceptive role of the pineal eye could also have accompanied its loss.

  2. Endocranial Casts of Pre-Mammalian Therapsids Reveal an Unexpected Neurological Diversity at the Deep Evolutionary Root of Mammals.

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    Benoit, Julien; Fernandez, Vincent; Manger, Paul R; Rubidge, Bruce S

    2017-01-01

    The origin and evolution of the mammalian brain has long been the focus of scientific enquiry. Conversely, little research has focused on the palaeoneurology of the stem group of Mammaliaformes, the Permian and Triassic non-mammaliaform Therapsida (NMT). This is because the majority of the NMT have a non-ossified braincase, making the study of their endocranial cast (sometimes called the "fossil brain") problematic. Thus, descriptions of the morphology and size of NMT endocranial casts have been based largely on approximations rather than reliable determination. Accordingly, here we use micro-CT scans of the skulls of 1 Dinocephalia and 3 Biarmosuchia, which are NMT with a fully ossified braincase and thus a complete endocast. For the first time, our work enables the accurate determination of endocranial shape and size in NMT. This study suggests that NMT brain size falls in the upper range of the reptilian and amphibian variation. Brain size in the dicynodont Kawingasaurus is equivalent to that of early Mammaliaformes, whereas the Dinocephalia show evidence of a secondary reduction of brain size. In addition, unlike other NMT in which the endocast has a tubular shape and its parts are arranged in a linear manner, the biarmosuchian endocast is strongly flexed at the level of the midbrain, creating a near right angle between the fore- and hindbrain. These data highlight an unexpected diversity of endocranial size and morphology in NMT, features that are usually considered conservative in this group. © 2017 S. Karger AG, Basel.

  3. Genomic assessment of the evolution of the prion protein gene family in vertebrates.

    Science.gov (United States)

    Harrison, Paul M; Khachane, Amit; Kumar, Manish

    2010-05-01

    Prion diseases are devastating neurological disorders caused by the propagation of particles containing an alternative beta-sheet-rich form of the prion protein (PrP). Genes paralogous to PrP, called Doppel and Shadoo, have been identified, that also have neuropathological relevance. To aid in the further functional characterization of PrP and its relatives, we annotated completely the PrP gene family (PrP-GF), in the genomes of 42 vertebrates, through combined strategic application of gene prediction programs and advanced remote homology detection techniques (such as HMMs, PSI-TBLASTN and pGenThreader). We have uncovered several previously undescribed paralogous genes and pseudogenes. We find that current high-quality genomic evidence indicates that the PrP relative Doppel, was likely present in the last common ancestor of present-day Tetrapoda, but was lost in the bird lineage, since its divergence from reptiles. Using the new gene annotations, we have defined the consensus of structural features that are characteristic of the PrP and Doppel structures, across diverse Tetrapoda clades. Furthermore, we describe in detail a transcribed pseudogene derived from Shadoo that is conserved across primates, and that overlaps the meiosis gene, SYCE1, thus possibly regulating its expression. In addition, we analysed the locus of PRNP/PRND for significant conservation across the genomic DNA of eleven mammals, and determined the phylogenetic penetration of non-coding exons. The genomic evidence indicates that the second PRNP non-coding exon found in even-toed ungulates and rodents, is conserved in all high-coverage genome assemblies of primates (human, chimp, orang utan and macaque), and is, at least, likely to have fallen out of use during primate speciation. Furthermore, we have demonstrated that the PRNT gene (at the PRNP human locus) is conserved across at least sixteen mammals, and evolves like a long non-coding RNA, fashioned from fragments of ancient, long

  4. Extreme Modification of the Tetrapod Forelimb in a Triassic Diapsid Reptile.

    Science.gov (United States)

    Pritchard, Adam C; Turner, Alan H; Irmis, Randall B; Nesbitt, Sterling J; Smith, Nathan D

    2016-10-24

    The tetrapod forelimb is one of the most versatile structures in vertebrate evolution, having been co-opted for an enormous array of functions. However, the structural relationships between the bones of the forelimb have remained largely unchanged throughout the 375 million year history of Tetrapoda, with a radius and ulna made up of elongate, paralleling shafts contacting a series of shorter carpal bones. These features are consistent across nearly all known tetrapods, suggesting that the morphospace encompassed by these taxa is limited by some sort of constraint(s). Here, we report on a series of three-dimensionally preserved fossils of the small-bodied (reptile Drepanosaurus, from the Chinle Formation of New Mexico, USA, which dramatically diverge from this pattern. Along with the crushed type specimen from Italy, these specimens have a flattened, crescent-shaped ulna with a long axis perpendicular to that of the radius and hyperelongate, shaft-like carpal bones contacting the ulna that are proximodistally longer than the radius. The second digit supports a massive, hooked claw. This condition has similarities to living "hook-and-pull" digging mammals and demonstrates that specialized, modern ecological roles had developed during the Triassic Period, over 200 million years ago. The forelimb bones in Drepanosaurus represent previously unknown morphologies for a tetrapod and, thus, a dramatic expansion of known tetrapod forelimb morphospace. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Confusing dinosaurs with mammals: tetrapod phylogenetics and anatomical terminology in the world of homology.

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    Harris, Jerald D

    2004-12-01

    At present, three different systems of anatomical nomenclature are available to researchers describing new tetrapod taxa: a nonstandardized traditional system erected in part by Sir Richard Owen and subsequently elaborated by Alfred Romer; a standardized system created for avians, the Nomina Anatomica Avium (NAA); and a standardized system for extant (crown-group) mammals, the Nomina Anatomica Veterinaria (NAV). Conserved homologous structures widely distributed within the Tetrapoda are often granted different names in each system. The recent shift toward a phylogenetic system based on homology requires a concomitant shift toward a single nomenclatural system also based on both evolutionary and functional morphological homology. Standardized terms employed in the NAA and NAV should be perpetuated as far as possible basally in their respective phylogenies. Thus, NAA terms apply to nonavian archosaurs (or even all diapsids) and NAV terms apply to noncrown-group mammals and more basal synapsids. Taxa equally distant from both avians and crown-group mammals may maintain the traditional nonstandardized terminology until a universal anatomical nomenclature for all tetrapods is constructed. (c) 2004 Wiley-Liss, Inc.

  6. Bringing Dicynodonts Back to Life: Paleobiology and Anatomy of a New Emydopoid Genus from the Upper Permian of Mozambique

    Science.gov (United States)

    Júnior, Luís C.; Angielczyk, Kenneth D.; Martins, Gabriel G.; Martins, Rui M. S.; Chaouiya, Claudine; Beckmann, Felix; Wilde, Fabian

    2013-01-01

    Dicynodontia represent the most diverse tetrapod group during the Late Permian. They survived the Permo-Triassic extinction and are central to understanding Permo-Triassic terrestrial ecosystems. Although extensively studied, several aspects of dicynodont paleobiology such as, neuroanatomy, inner ear morphology and internal cranial anatomy remain obscure. Here we describe a new dicynodont (Therapsida, Anomodontia) from northern Mozambique: Niassodon mfumukasi gen. et sp. nov. The holotype ML1620 was collected from the Late Permian K5 formation, Metangula Graben, Niassa Province northern Mozambique, an almost completely unexplored basin and country for vertebrate paleontology. Synchrotron radiation based micro-computed tomography (SRµCT), combined with a phylogenetic analysis, demonstrates a set of characters shared with Emydopoidea. All individual bones were digitally segmented allowing a 3D visualization of each element. In addition, we reconstructed the osseous labyrinth, endocast, cranial nerves and vasculature. The brain is narrow and the cerebellum is broader than the forebrain, resembling the conservative, “reptilian-grade” morphology of other non-mammalian therapsids, but the enlarged paraflocculi occupy the same relative volume as in birds. The orientation of the horizontal semicircular canals indicates a slightly more dorsally tilted head posture than previously assumed in other dicynodonts. In addition, synchrotron data shows a secondary center of ossification in the femur. Thus ML1620 represents, to our knowledge, the oldest fossil evidence of a secondary center of ossification, pushing back the evolutionary origins of this feature. The fact that the specimen represents a new species indicates that the Late Permian tetrapod fauna of east Africa is still incompletely known. PMID:24324653

  7. Bringing dicynodonts back to life: paleobiology and anatomy of a new emydopoid genus from the Upper Permian of Mozambique.

    Directory of Open Access Journals (Sweden)

    Rui Castanhinha

    Full Text Available Dicynodontia represent the most diverse tetrapod group during the Late Permian. They survived the Permo-Triassic extinction and are central to understanding Permo-Triassic terrestrial ecosystems. Although extensively studied, several aspects of dicynodont paleobiology such as, neuroanatomy, inner ear morphology and internal cranial anatomy remain obscure. Here we describe a new dicynodont (Therapsida, Anomodontia from northern Mozambique: Niassodon mfumukasi gen. et sp. nov. The holotype ML1620 was collected from the Late Permian K5 formation, Metangula Graben, Niassa Province northern Mozambique, an almost completely unexplored basin and country for vertebrate paleontology. Synchrotron radiation based micro-computed tomography (SRµCT, combined with a phylogenetic analysis, demonstrates a set of characters shared with Emydopoidea. All individual bones were digitally segmented allowing a 3D visualization of each element. In addition, we reconstructed the osseous labyrinth, endocast, cranial nerves and vasculature. The brain is narrow and the cerebellum is broader than the forebrain, resembling the conservative, "reptilian-grade" morphology of other non-mammalian therapsids, but the enlarged paraflocculi occupy the same relative volume as in birds. The orientation of the horizontal semicircular canals indicates a slightly more dorsally tilted head posture than previously assumed in other dicynodonts. In addition, synchrotron data shows a secondary center of ossification in the femur. Thus ML1620 represents, to our knowledge, the oldest fossil evidence of a secondary center of ossification, pushing back the evolutionary origins of this feature. The fact that the specimen represents a new species indicates that the Late Permian tetrapod fauna of east Africa is still incompletely known.

  8. PRIMITIVISME IKAN POLYPTERUS SEBAGAI WARISAN MANUSIA MODERN

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    Media Fitri Isma Nugraha

    2010-12-01

    Full Text Available Tinjauan ini mensintesa historis dan diversitas ikan purba Polypterus yang berasal dari Afrika sebagai komoditi budidaya ikan hias. Sejarah evolusinya sangat unik, muncul sejak pertengahan Miocen (10 juta tahun, hubungan parentalnya berada pada posisi transisional sister-takson antara Teleostei dan Tetrapoda. Primitivismenya menyisakan divergensi momental sains hampir satu abad dalam determinasi dimorfisme seksualnya. Bersifat nokturnal, tahan terhadap kondisi habitat ekstrim tetapi mudah dibudidayakan. Polypterus jantan memiliki sirip anal tebal dan condong ke hipural konjungsi sirip ekor. Seekor betina mampu bertelur 100–300 butir dan menetas kurang dari 3 hari. Benih Polypterus sudah dapat beradaptasi dengan pakan tambahan sekitar 10 hari pasca menetas, dan dalam perkembangan gonad jantan dan betina akan terbentuk sempurna setelah berumur 10 bulan. Fosil hidup Polypterus telah menjadi warisan dunia, adopsi dan asuhan penggemarnya tersebar ke-5 benua, dapat dilaporkan bahwa harga per ekor dipatok variatif antara US$40–US$70. Kegemaran kita membudidayakannya, berarti telah menyelamatkan populasi ikan ini agar terhindar dari kepunahan. Atas dasar konsesi dan semangat terhadap warisan spesies dunia itu, BRBIH Depok telah mengoleksi dan sukses memproduksi satu sub spesies, satu varian intergenetik-albino dari populasi Polypterus senegalus senegalus dan 3 spesies intragenerik lainnya.

  9. Comparative anatomy, homologies and evolution of the pectoral and forelimb musculature of tetrapods with special attention to extant limbed amphibians and reptiles.

    Science.gov (United States)

    Abdala, Virginia; Diogo, Rui

    2010-11-01

    The main aim of the present work is to synthesize the information obtained from our dissections of the pectoral and forelimb muscles of representative members of the major extant taxa of limbed amphibians and reptiles and from our review of the literature, in order to provide an account of the comparative anatomy, homologies and evolution of these muscles in the Tetrapoda. The pectoral and forelimb musculature of all these major taxa conform to a general pattern that seems to have been acquired very early in the evolutionary history of tetrapods. Although some muscles are missing in certain taxa, and a clear departure from this general pattern is obviously present in derived groups such as birds, the same overall configuration is easily distinguishable in these taxa. Among the most notable anatomical differences between the groups, one that seems to have relevant evolutionary and functional implications, concerns the distal insertion points of the forearm musculature. In tetrapods, the muscles of the radial and ulnar complexes of the forearm are pleisomorphically mainly inserted onto the radius/ulna or onto the more proximal carpal bones, but in mammals some of these muscles insert more distally onto bones such as the metacarpals. Interestingly, a similar trend towards a more distal insertion of these muscles is also found in some non-mammalian tetrapod taxa, such as some anurans (e.g. Phyllomedusa). This may be correlated with the acquisition of more subtle digital movement abilities in these latter taxa. © 2010 The Authors. Journal of Anatomy © 2010 Anatomical Society of Great Britain and Ireland.

  10. Is evolutionary biology becoming too politically correct? A reflection on the scala naturae, phylogenetically basal clades, anatomically plesiomorphic taxa, and 'lower' animals.

    Science.gov (United States)

    Diogo, Rui; Ziermann, Janine M; Linde-Medina, Marta

    2015-05-01

    The notion of scala naturae dates back to thinkers such as Aristotle, who placed plants below animals and ranked the latter along a graded scale of complexity from 'lower' to 'higher' animals, such as humans. In the last decades, evolutionary biologists have tended to move from one extreme (i.e. the idea of scala naturae or the existence of a general evolutionary trend in complexity from 'lower' to "higher" taxa, with Homo sapiens as the end stage) to the other, opposite, extreme (i.e. to avoid using terms such as 'phylogenetically basal' and 'anatomically plesiomorphic' taxa, which are seen as the undesired vestige of old teleological theories). The latter view tries to avoid any possible connotations with the original anthropocentric idea of a scala naturae crowned by man and, in that sense, it can be regarded as a more politically correct view. In the past years and months there has been renewed interest in these topics, which have been discussed in various papers and monographs that tend to subscribe, in general, to the points defended in the more politically correct view. Importantly, most evolutionary and phylogenetic studies of tetrapods and other vertebrates, and therefore most discussions on the scala naturae and related issues have been based on hard tissue and, more recently, on molecular data. Here we provide the first discussion of these topics based on a comparative myological study of all the major vertebrate clades and of myological cladistic and Bayesian phylogenetic analyses of bony fish and tetrapods, including Primates. We specifically (i) contradict the notions of a scala naturae or evolutionary progressive trends leading to more complexity in 'higher' animals and culminating in Homo sapiens, and (ii) stress that the refutation of these old notions does not necessarily mean that one should not keep using the terms 'phylogenetically basal' and particularly 'anatomically plesiomorphic' to refer to groups such as the urodeles within the Tetrapoda

  11. Structural evolution and tissue-specific expression of tetrapod-specific second isoform of secretory pathway Ca{sup 2+}-ATPase

    Energy Technology Data Exchange (ETDEWEB)

    Pestov, Nikolay B., E-mail: korn@mail.ibch.ru [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117871 (Russian Federation); Dmitriev, Ruslan I.; Kostina, Maria B. [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117871 (Russian Federation); Korneenko, Tatyana V. [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117871 (Russian Federation); Department of Physiology and Pharmacology, University of Toledo College of Medicine, 3000 Arlington Ave., Toledo, OH 43614 (United States); Shakhparonov, Mikhail I. [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117871 (Russian Federation); Modyanov, Nikolai N., E-mail: nikolai.modyanov@utoledo.edu [Department of Physiology and Pharmacology, University of Toledo College of Medicine, 3000 Arlington Ave., Toledo, OH 43614 (United States)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Full-length secretory pathway Ca-ATPase (SPCA2) cloned from rat duodenum. Black-Right-Pointing-Pointer ATP2C2 gene (encoding SPCA2) exists only in genomes of Tetrapoda. Black-Right-Pointing-Pointer Rat and pig SPCA2 are expressed in intestines, lung and some secretory glands. Black-Right-Pointing-Pointer Subcellular localization of SPCA2 may depend on tissue type. Black-Right-Pointing-Pointer In rat duodenum, SPCA2 is localized in plasma membrane-associated compartments. -- Abstract: Secretory pathway Ca-ATPases are less characterized mammalian calcium pumps than plasma membrane Ca-ATPases and sarco-endoplasmic reticulum Ca-ATPases. Here we report analysis of molecular evolution, alternative splicing, tissue-specific expression and subcellular localization of the second isoform of the secretory pathway Ca-ATPase (SPCA2), the product of the ATP2C2 gene. The primary structure of SPCA2 from rat duodenum deduced from full-length transcript contains 944 amino acid residues, and exhibits 65% sequence identity with known SPCA1. The rat SPCA2 sequence is also highly homologous to putative human protein KIAA0703, however, the latter seems to have an aberrant N-terminus originating from intron 2. The tissue-specificity of SPCA2 expression is different from ubiquitous SPCA1. Rat SPCA2 transcripts were detected predominantly in gastrointestinal tract, lung, trachea, lactating mammary gland, skin and preputial gland. In the newborn pig, the expression profile is very similar with one remarkable exception: porcine bulbourethral gland gave the strongest signal. Upon overexpression in cultured cells, SPCA2 shows an intracellular distribution with remarkable enrichment in Golgi. However, in vivo SPCA2 may be localized in compartments that differ among various tissues: it is intracellular in epidermis, but enriched in plasma membranes of the intestinal epithelium. Analysis of SPCA2 sequences from various vertebrate species argue that ATP2C2

  12. Structural evolution and tissue-specific expression of tetrapod-specific second isoform of secretory pathway Ca2+-ATPase

    International Nuclear Information System (INIS)

    Pestov, Nikolay B.; Dmitriev, Ruslan I.; Kostina, Maria B.; Korneenko, Tatyana V.; Shakhparonov, Mikhail I.; Modyanov, Nikolai N.

    2012-01-01

    Highlights: ► Full-length secretory pathway Ca-ATPase (SPCA2) cloned from rat duodenum. ► ATP2C2 gene (encoding SPCA2) exists only in genomes of Tetrapoda. ► Rat and pig SPCA2 are expressed in intestines, lung and some secretory glands. ► Subcellular localization of SPCA2 may depend on tissue type. ► In rat duodenum, SPCA2 is localized in plasma membrane-associated compartments. -- Abstract: Secretory pathway Ca-ATPases are less characterized mammalian calcium pumps than plasma membrane Ca-ATPases and sarco-endoplasmic reticulum Ca-ATPases. Here we report analysis of molecular evolution, alternative splicing, tissue-specific expression and subcellular localization of the second isoform of the secretory pathway Ca-ATPase (SPCA2), the product of the ATP2C2 gene. The primary structure of SPCA2 from rat duodenum deduced from full-length transcript contains 944 amino acid residues, and exhibits 65% sequence identity with known SPCA1. The rat SPCA2 sequence is also highly homologous to putative human protein KIAA0703, however, the latter seems to have an aberrant N-terminus originating from intron 2. The tissue-specificity of SPCA2 expression is different from ubiquitous SPCA1. Rat SPCA2 transcripts were detected predominantly in gastrointestinal tract, lung, trachea, lactating mammary gland, skin and preputial gland. In the newborn pig, the expression profile is very similar with one remarkable exception: porcine bulbourethral gland gave the strongest signal. Upon overexpression in cultured cells, SPCA2 shows an intracellular distribution with remarkable enrichment in Golgi. However, in vivo SPCA2 may be localized in compartments that differ among various tissues: it is intracellular in epidermis, but enriched in plasma membranes of the intestinal epithelium. Analysis of SPCA2 sequences from various vertebrate species argue that ATP2C2 gene radiated from ATP2C1 (encoding SPCA1) during adaptation of tetrapod ancestors to terrestrial habitats.

  13. Early tetrapod relationships revisited.

    Science.gov (United States)

    Ruta, Marcello; Coates, Michael I; Quicke, Donald L J

    2003-05-01

    In an attempt to investigate differences between the most widely discussed hypotheses of early tetrapod relationships, we assembled a new data matrix including 90 taxa coded for 319 cranial and postcranial characters. We have incorporated, where possible, original observations of numerous taxa spread throughout the major tetrapod clades. A stem-based (total-group) definition of Tetrapoda is preferred over apomorphy- and node-based (crown-group) definitions. This definition is operational, since it is based on a formal character analysis. A PAUP* search using a recently implemented version of the parsimony ratchet method yields 64 shortest trees. Differences between these trees concern: (1) the internal relationships of aïstopods, the three selected species of which form a trichotomy; (2) the internal relationships of embolomeres, with Archeria crassidisca and Pholiderpeton scut collapsed in a trichotomy with a clade formed by Anthracosaurus russelli and Pholiderpeton attheyi; (3) the internal relationships of derived dissorophoids, with four amphibamid species forming an unresolved node with a clade consisting of micromelerpetontids and branchiosaurids and a clade consisting of albanerpetontids plus basal crown-group lissamphibians; (4) the position of albenerpetontids and Eocaecilia micropoda, which form an unresolved node with a trichotomy subtending Karaurus sharovi, Valdotriton gracilis and Triadobatrachus massinoti; (5) the branching pattern of derived diplocaulid nectrideans, with Batrachiderpeton reticulatum and Diceratosaurus brevirostris collapsed in a trichotomy with a clade formed by Diplocaulus magnicornis and Diploceraspis burkei. The results of the original parsimony run--as well as those retrieved from several other treatments of the data set (e.g. exclusion of postcranial and lower jaw data; character reweighting; reverse weighting)--indicate a deep split of early tetrapods between lissamphibian- and amniote-related taxa. Colosteids, Crassigyrinus

  14. Programa de Pós-Graduação em Geologia - Dissertações Defendidas 1998 - Mestrado - Instituto de Geociências - Universidade Federal do Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    1998-01-01

    Anuário do Instituto de Geociências - UFRJ Volume 21 / 1998 do Paraná, localizada na região de Pinheiros, pertencentes ao município de Candelária, Rio Grande do Sul. Os coprólitos estudados estão relacionados à paleoherpetofauna da cenozona Therapsida e permitem inferir sobre paleoecologia e o paleoclima da região durante este momento do Triássico. As 22 amostras são compostas por um conjunto de 50 massas aglomeradas ou isoladas, classificadas em tipos ovóides e cilíndricos. Os coprólitos foram coletados em quatro afloramentos, que pertencem ao conjunto de ravinas denominadas regionalmente de sangas. Nestes afloramentos os restos de répteis mamaliformes (dicinodontes e cinodontes e arcosssauros (tecodontes encontram-se fartamente distribuídos em vários níveis do perfil, sem qualquer zona preferencial de concentração. As amostras foram classificadas pelas formas e descritas pelos aspectos externos (cor, polaridade e textura da superfície e internos, através da utilização de diferentes análises de raios-x (emissão, difratometria e fluorescência e corte de lâmina. A avaliação dos aspectos quantitativos das amostras foram realizados através da aplicação estatística do cálculo da freqüência de classes e do coeficiente de variação, necessários na caracterização e investigação das afinidades dos grupamentos. Entre os aspectos apresentados em superfície, os resultados de agretamento e de coprofagia, informam sobre condições paleobiológicas e paleoclimáticas no momento em que os coprólitos foram produzidos. Os coprólitos de forma ovóide caracterizados pela maior variação do tamanho, gretas e estruturas vegetais, confirmam aspectos de afinidade com excrementos de dieta herbívora. As formas cilíndricas de peso e tamanho mais uniformes são caracterizadas pelo alto grau de compactação interna, relacionando estes excrementos como provenientes de dieta carnívora ou omnívora. A composição mineralógica apresentada na an