Academic literature on the topic 'Dicynodontes'
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Journal articles on the topic "Dicynodontes"
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Fröbisch, Jörg. "Locomotion in derived dicynodonts (Synapsida, Anomodontia): a functional analysis of the pelvic girdle and hind limb of Tetragonias njalilus." Canadian Journal of Earth Sciences 43, no. 9 (September 1, 2006): 1297–308. http://dx.doi.org/10.1139/e06-031.
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A general locomotor model for derived dicynodont anomodonts is proposed on the basis of a functional analysis of the pelvic girdle and entire hind limb of the medium-sized Middle Triassic dicynodont Tetragonias njalilus. The joint mobility of the hind limb is examined, and a hind limb step cycle is reconstructed. The data provided in this case study indicate that Tetragonias adopted a highly adducted (upright) hind limb posture during stance and most of its stride. Nevertheless, lateral undulation of the vertebral column must also have contributed to the locomotion of dicynodonts. Character optimization of the traits associated with an upright posture of the hind limb shows a gradual evolution of dicynodont locomotion. The evolution of an upright hind limb posture has occurred several times independently in a number of amniote clades. Within synapsids, the Anomodontia, Dinocephalia, and Theriodontia acquired a parasagittal hind limb gait already as early as the late Paleozoic and early Mesozoic, prior to its evolution in mammals. This phenomenon has previously been explained as being related to an increase in body size as a response to increased biomechanical stress on the limb. This scenario appears plausible with respect to dicynodonts because of the occurrence of megaherbivore-sized taxa in the Triassic, but this study shows that a parasagittal gait had already evolved in the medium-sized basal kannemeyeriiform Tetragonias. Therefore, the vertical support of the body by the hind limbs in medium-sized dicynodonts could have allowed the evolution of the large Triassic taxa in the first place.
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Lucas, Spencer G. "Barysoma lenzii (Synapsida: Dicynodontia) from the Middle Triassic of Brazil, a synonym of Stahleckeria potens." Journal of Paleontology 67, no. 2 (March 1993): 318–21. http://dx.doi.org/10.1017/s0022336000032285.
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Huene (1935) first reported dicynodonts from the Triassic Santa Maria Formation of southern Brazil. Most common are specimens of Dinodontosaurus from localities near Chiniquà (Chiniquà local fauna) and near Candelaria (Candelaria local fauna) in the state of Rio Grande do Sul. The other Middle Triassic dicynodont found near Chiniquà is the huge (about 3 m body length) Stahleckeria potens, and an equally large Middle Triassic dicynodont, Barysoma lenzii, is known from near Candelaria. A fourth, supposed Santa Maria Formation dicynodont, Jachaleria candelariensis (Araújo and Gonzaga, 1990), is actually from a younger, Upper Triassic, horizon of the Caturrita Formation near Candelaria (Bonaparte, 1982). Here, I argue that Barysoma lenzii is a junior subjective synonym of Stahleckeria potens and discuss the biochronological significance of this synonymy.
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Griffin, Christopher T., and Kenneth D. Angielczyk. "The evolution of the dicynodont sacrum: constraint and innovation in the synapsid axial column." Paleobiology 45, no. 1 (February 2019): 201–20. http://dx.doi.org/10.1017/pab.2018.49.
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AbstractConstraint is a universal feature of morphological evolution. The vertebral column of synapsids (mammals and their close relatives) is a classic example of this phenotypic restriction, with greatly reduced variation in the number of vertebrae compared with the sauropsid lineage. Synapsids generally possess only three sacral vertebrae, which articulate with the ilium and play a key role in locomotion. Dicynodont anomodonts are the exception to this rule, possessing seven or more sacral vertebrae while reaching a range of body sizes rivaled among synapsids only by therian mammals. Here we explore the evolution of this unusual sacral morphology in dicynodonts by (1) hypothesizing homologies of the additional sacral vertebrae, (2) using ancestral state reconstruction and phylogenetic regressions (e.g., logistic regression, Poisson regression) to track the coevolution of sacral count and body size, and (3) proposing mechanisms by which additional sacral vertebrae were incorporated during dicynodont evolution. We find that sacral vertebral morphology covaries with sacral count in consistent ways across dicynodonts, implying that sacra with a given number of vertebrae are composed of homologous elements. There is a correlation between increased sacral count and larger body size, especially at the shift from four to five sacrals near the origin of Bidentalia. Based on position, morphology, and the consistent number of presacral vertebrae among dicynodonts, we hypothesize that the additional sacrals anterior to the plesiomorphic three are duplications of the first sacral, and that a single caudosacral was incorporated by a shift in the identity of the anteriormost caudal vertebra. Although changes in sacral count appear to be correlated with shifts in body size in dicynodonts, the evolution of general morphological conservativism in the synapsid sacrum remains to be further explored.
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Sulej, Tomasz, Robert Bronowicz, Mateusz Tałanda, and Grzegorz Niedźwiedzki. "A new dicynodont–archosaur assemblage from the Late Triassic (Carnian) of Poland." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101, no. 3-4 (September 2010): 261–69. http://dx.doi.org/10.1017/s1755691011020123.
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ABSTRACTThis paper reports a new assemblage from the Late Triassic (mid–late Carnian) at Woźniki near Częstochowa (Poland). The Woźniki vertebrate assemblage is similar to that of Lisowice–Lipie Śląskie, a new locality bearing vertebrates from latest Triassic (latest Norian–early Rhaetian) strata of southern Poland, in the presence of dicynodonts, shark spines, plagiosaurs and a cyclotosaur, but conchostracans and bivalves are similar to those from the Krasiejów site (late Carnian). The most complete specimen from Woźniki belongs to a dicynodont, and consists of cranial and postcranial bones of a single individual. It demonstrates that large dicynodonts were part of the Late Triassic vertebrate assemblage in Central Europe. Numerous tetrapod tracks and traces are associated with skeletal fossils at Woźniki.
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Modesto, Sean P., Bruce S. Rubidge, and Johann Welman. "A new dicynodont therapsid from the lowermost Beaufort Group, Upper Permian of South Africa." Canadian Journal of Earth Sciences 39, no. 12 (December 1, 2002): 1755–65. http://dx.doi.org/10.1139/e02-091.
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Two fragmentary skulls from the Upper Permian Tapinocephalus Assemblage Zone (Abrahamskraal Formation, Beaufort Group) in Eastern Cape Province, South Africa, represent a new dicynodont taxon. Lanthanocephalus mohoii gen. et sp. nov. is distinguished from other dicynodonts by the presence of a conspicuous laterally facing excavation on the dorsal surface of the postfrontal, by dorsal expansions of the supraoccipital that contact the parietals, and by extensive ossification of the lateral wall of the braincase. Lanthanocephalus features several characters that are suggestive of a close relationship with Endothiodon. These include a transversely narrow intertemporal region, the presence of a pineal boss, and the presence of a distinct boss on the ventral margin of the jugal. Cladistic analysis of a modified data matrix from the literature supports the hypothesis of a sister-group relationship between Lanthanocephalus and Endothiodon. However, this grouping and most others found in the analysis collapse with one extra step, weaknesses that underscore the need for further research on dicynodonts and other non-mammalian synapsids.
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Kammerer, Christian F., and Roger M. H. Smith. "An early geikiid dicynodont from theTropidostomaAssemblage Zone (late Permian) of South Africa." PeerJ 5 (January 31, 2017): e2913. http://dx.doi.org/10.7717/peerj.2913.
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Based on specimens previously identified asTropidostoma, a new taxon of dicynodont (Bulbasaurus phylloxyrongen. et sp. nov.) from the Karoo Basin of South Africa is described.Bulbasaurusis a medium-sized dicynodont (maximum dorsal skull length 16.0 cm) restricted to theTropidostomaAssemblage Zone (early Lopingian) of the Beaufort Group.Bulbasauruscan be distinguished fromTropidostomaby 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 ofBulbasaurusin a phylogenetic analysis of anomodont therapsids recovers it as a member of Geikiidae, a clade of otherwise later Permian dicynodonts such asAulacephalodonandPelanomodon.Bulbasaurusexhibits many of the characters typical of adultAulacephalodon, but at substantially smaller skull size (these characters are absent in comparably-sizedAulacephalodonjuveniles), suggesting that the evolution of typical geikiid morphology preceded gigantism in the clade.Bulbasaurusis the earliest known geikiid and the only member of the group known from theTropidostomaAssemblage 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.
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Angielczyk, Kenneth D. "Redescription, phylogenetic position, and stratigraphic significance of the dicynodont genus Odontocyclops (Synapsida: Anomodontia)." Journal of Paleontology 76, no. 6 (November 2002): 1047–59. http://dx.doi.org/10.1017/s0022336000057863.
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The dicynodont anomodont Odontocyclops whaitsi, from the Late Permian Madumabisa Mudstone of Zambia, is redescribed and its phylogenetic relationships are considered. The genus is characterized by a two autapomorphies, elongate nasal bosses and a concave dorsal surface of the snout; it also possesses wide exposure of the parietals on the intertemporal skull roof, the presence of a postcaniniform crest, the absence of a labial fossa, and the presence of a dorsal process on the anterior ramus of the epipterygoid footplate. In addition, newly recognized specimens collected in South Africa extend the known geographic range of the genus and allow description of the humerus and scapula for the first time. Cladistic analysis of a data set including Odontocyclops and 18 other well-known South African dicynodont genera does not support the hypothesis that Odontocyclops is a close relative of Dicynodon or of Triassic dicynodonts such as Kannemeyeria. Instead, a close relationship with Oudenodon and Rhachiocephalus is proposed. The presence of Odontocyclops in South Africa and Zambia makes it potentially valuable for more precise biostratigraphic correlation between the sediments of the Karoo Basin and the Luangwa Valley.
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Shi, Yu-Tai, and Jun Liu. "The tetrapod fauna of the upper Permian Naobaogou Formation of China: 10. Jimusaria monanensis sp. nov. (Dicynodontia) shows a unique epipterygoid." PeerJ 11 (July 31, 2023): e15783. http://dx.doi.org/10.7717/peerj.15783.
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Jimusaria is the first reported Chinese dicynodont, previously only known from Xinjiang. Here we refer two specimens from the Naobaogou Formation, Nei Mongol, China to Jimusaria based on the following features: squamosal separated from supraoccipital by tabular, tabular contacting opisthotic, sharp and thin lateral dentary shelf expanding anteriorly into a thick swelling, nasals fused as single element, rod-like medial bar formed by footplate of epipterygoid connecting to the parabasisphenoid and periotic medially. A new species, J. monanensis, is named based on the diagnostic characters on these two specimens such as distinct caniniform buttress lacking posteroventral furrow, naso-frontal suture forming an anterior directed sharp angle, and converging ventral ridges on posterior portion of anterior pterygoid rami. In Jimusaria, the epipterygoid posteromedially contacts the parabasisphenoid and the periotic as a rod-like bar, a unique morphology unknown in any other dicynodonts. This structure probably increases the stability of the palatal complex. A similar structure might also appear in other dicynodonts as a cartilage connection. The new occurrence of Jimusaria increases the diversity of the tetrapod assemblage from the Naobaogou Formation, and further strengthens the connection between the tetrapod faunas from Nei Mongol and Xinjiang. Based on the current record, Jimusaria is one of the few tetrapod genera which survived in the end-Permian mass extinction.
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Day, M. O., and R. M. H. Smith. "Biostratigraphy of the Endothiodon Assemblage Zone (Beaufort Group, Karoo Supergroup), South Africa." South African Journal of Geology 123, no. 2 (June 1, 2020): 165–80. http://dx.doi.org/10.25131/sajg.123.0011.
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Abstract The Endothiodon Assemblage Zone is the third oldest tetrapod biozone of the Beaufort Group (Adelaide Subgroup, Karoo Supergroup). It is situated between the underlying Tapinocephalus and overlying Cistecephalus assemblage zones and in the southwestern part of the basin corresponds to the majority of the Poortjie and Hoedemaker members of the Teekloof Formation. It is characterised by the dicynodont genus Endothiodon, especially in the lower part of assemblage zone, and records early ecosystem recovery from the Capitanian mass extinction. It also contains the lowest occurrence in the Karoo Basin of cynodont therapsids, eutherocephalians, bidentalian dicynodonts, and diapsids. The biozone reaches a maximum thickness of around 250 m in the southwestern part of the basin. We propose a two-fold subdivision into a lower Lycosuchus - Eunotosaurus Subzone (equivalent to the upper two-thirds of the former Pristerognathus Assemblage Zone) and an upper Tropidostoma - Gorgonops Subzone (equivalent to the former Tropidostoma Assemblage Zone), with the contact defined by the first appearance of Tropidostoma dubium. The Endothiodon Assemblage Zone is terminated by the first appearance of Aulacephalodon bainii.
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Kammerer, Christian F. "Revision of the Tanzanian dicynodont Dicynodon huenei (Therapsida: Anomodontia) from the Permian Usili Formation." PeerJ 7 (August 22, 2019): e7420. http://dx.doi.org/10.7717/peerj.7420.
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A single species of the dicynodontoid dicynodont Dicynodon is currently recognized from the late Permian Usili Formation of Tanzania: Dicynodon huenei Haughton, 1932. Restudy of the known Tanzanian materials of D. huenei demonstrates that they represent two distinct morphotypes, here considered separate taxa. The holotype of D. huenei is not referable to Dicynodon and instead is transferred to the genus Daptocephalus (but retained as a valid species, Daptocephalus huenei comb. nov.). A number of published dicynodontoid specimens from the Usili Formation, however, are referable to Dicynodon, and are here recognized as a new species (Dicynodon angielczyki sp. nov.) Dicynodon angielczyki can be distinguished from its South African congener Dicynodon lacerticeps by the presence of an expansion of the squamosal and jugal beneath the postorbital bar and a curved, posterolateral expansion of the squamosal behind the temporal fenestra. Inclusion of Dicynodon angielczyki and D. huenei in a phylogenetic analysis supports their referral to Dicynodon and Daptocephalus (respectively). These results indicate higher basinal endemism in large late Permian dicynodonts than previously thought, a sharp contrast to the cosmopolitanism in the group in the earliest Triassic.
Dissertations / Theses on the topic "Dicynodontes"
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Olivier, Chloé. "Phylogeny, paleobiogeography, and paleophysiology of the Triassic dicynodonts (Therapsida, Anomodontia) : contributions of the Laotian and Moroccan forms." Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS399.pdf.
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Les dicynodontes sont emblématiques de la période du Permien-Trias (P-Tr), du fait de leur survie à la grande crise P-Tr. Cependant, les conditions de leur résilience et leur évolution au cours du Trias restent peu connues. Ce travail s'est concentré sur les formes laotiennes et marocaines. La résilience des dicynodontes apparait plus précoce, de par l’ajout de deux nouvelles espèces laotiennes (Counillonia superoculis et Repelinosaurus robustus) datée du Trias inférieur. Malgré leurs relations phylogénétiques non consensuelles, elles confirment la survie de plusieurs lignées de dicynodontes à la crise. Les modèles paléophysiologiques ont conclu à une endothermie chez tous les dicynodontes permiens et triasiques étudiés, réfutant l’hypothèse d’un métabolisme élevé pour expliquer un différentiel de survie. Ils ont également montré une acquisition unique de l'endothermie mammalienne au moins au Permien moyen, chez les Neotherapsida. Du fait de l'âge et du mode de vie terrestre des dicynodontes, une connexion terrestre entre le bloc indochinois et la Pangée a donc été supposée au moins dès la fin Permien-début Trias. Du matériel post-crânien marocain inédit de dicynodonte a été étudié et une révision taxonomique des formes marocaines a été effectuée. Moghreberia nmachouensis a été considérée valide et distincte du genre Placerias. L’étude du matériel crânien d'Azarifeneria n'a pas permis de le distinguer des autres genres triasiques. Outre Moghreberia, un second morphotype plus robuste a été remarqué dans le matériel postcrânien. La grande taille de Moghreberia et de ce deuxième morphotype ont confirmé une augmentation de la taille corporelle des dicynodontes au cours du TriasDicynodonts represent an emblematic Permian-Triassic (P-Tr) taxa to survive the big crisis at the end of Permian. The evolution of Triassic dicynodonts and their recovery conditions are still unclear. This work focused on the Laotian and Moroccan forms. The post-crisis recovery of dicynodonts would appear to be earlier as supported by the description of two new Laotian species (Counillonia superoculis and Repelinosaurus robustus) in Early Triassic. Despite their non-consensual phylogenetic relationships, they support the survivorship of multiple lineages across the P-Tr boundary. Paleophysiological models inferred high metabolism in Permian and Triassic studied dicynodonts, refuting the hypothesis of a high metabolism to mainly explain differential survival beyond the crisis. They also highlighted a unique acquisition of the endothermy in Synapsida occurring at least in middle Permian at the Neotherapsida node. Considering the age and the terrestrial lifestyle of dicynodonts, a terrestrial connection between the Indochina Block and Pangea could thus be interpreted at least in late Permian-Early Triassic. A new dicynodont postcranial material discovered in Morocco was studied and a taxonomic revision of the Moroccan forms was made. Moghreberia nmachouensis was considered as valid and clearly distinguished from Placerias. The restudy of the cranial material of Azarifeneria did not allow distinguishing it from other Triassic genera. In addition to Moghreberia, a second morphotype, more robust, could be noticed in the postcranial material. The large size of Moghreberia and of the second big morphotype confirmed an increase of the body size in dicynodonts during the Triassic
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Morato, Duarte Leonardo. "Dinodontosaurus (Synapsida, Dicynodontia) reconstituições morfológicas e aspectos biomecânicos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/6217.
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Dicinodontes possuem um mosaico de características, que incluem, por exemplo, extrema redução dentária, movimento propalinal da mandíbula, e o desenvolvimento de uma postura diferenciada em alguns gêneros. Nesses, enquanto os membros anteriores permanecem abduzidos, em uma postura primitiva, os posteriores se tornam totalmente aduzidos. Para discutir aspectos paleobiológicos, foram efetuadas análises morfofuncionais e biomecânicas em espécimes do gênero Dinodontosaurus Romer, 1943, um dicinodonte de porte médio do Mesotriássico do estado do Rio Grande do Sul, Brasil. É endossada a sinonímia da maioria das espécies do gênero com Dinodontosaurus turpior, excetuando-se Dinodontosaurus platygnathus, cujos materiais apresentam características conflitantes, e é tratado aqui como nomen dubium. É apresentada uma sucinta descrição osteológica para as formas juvenis do gênero, nos quais se observa a presença de seis vértebras sacrais, além de um mínimo de 17 caudais, adicionando informações que permitem novas reconstruções esqueletais. Enfoque é dado na miologia facial e dos membros, com base na comparação de modelos para diferentes taxa, seguindo a abordagem de suporte filogenético de animais viventes. Apenas músculos de presença inequívoca são reconstituídos, a menos quando há argumentos morfológicos convincentes. A partir de observações morfofuncionais, é eliminada a possibilidade de Dinodontosaurus utilizar suas presas com a mandíbula aberta, seja para alimentação ou defesa, e é reforçado seu caráter como ornamentação Na falta de análogos posturais modernos, comparações com preguiças terrícolas extintas levaram alguns autores a propostas de uma postura bípede para os dicinodontes, ao menos facultativa, para se erguerem nas patas traseiras e alcançarem níveis mais elevados de vegetação. Para testar essa hipótese, foram abordados vários aspectos biomecânicos envolvidos na postura bípede, em Dinodontosaurus. Seu centro de massa foi localizado a partir da suspensão de modelos em argila, estando posicionado em um ponto, no plano sagital, aproximadamente na metade da distância entre os estilopódios anteriores e posteriores, um pouco mais próximo dos primeiros; para os indivíduos juvenis, um modelo digital obtido através de scanner 3D a laser também corroborou esse posicionamento, o que sugere que a postura bípede não poderia ser facilmente mantida sem apoio, e um caminhar bípede seria totalmente impraticável. Foram estimados os momentos de resistência da coluna vertebral, a partir de medidas da largura e altura dos centros vertebrais em sua borda posterior, sendo que os resultados foram compatíveis com um animal de postura quadrúpede. Foram também calculados os índices de capacidade atlética para os ossos longos dos membros anteriores e posteriores; para isso, foram estimadas as massas, com os indivíduos juvenis atingindo entre 23 e 32kg, enquanto o adulto não ultrapassaria 300kg. As massas foram obtidas baseando-se em estimativas de volume a partir de silhuetas e de modelos tridimensionais em computação Os valores obtidos para os índices de capacidade atlética são muito superiores aos de outros animais descritos na literatura, embora sejam compatíveis com outros terápsidos não-mamalianos julgados quadrúpedes, e estão na mesma ordem de grandeza entre os ossos dos membros anteriores e posteriores, o que também alude à postura quadrúpede. Através de observações morfológicas gerais, localização do centro de massa, estimativa de momentos de resistência da coluna vertebral e cálculo de índices de capacidade atlética para os membros, conclui-se que, ao menos no que concerne a Dinodontosaurus, não há evidências que suportem as analogias morfofuncionais com as preguiças terrícolas, animais que apresentam diversas adaptações para o bipedalismo. Os resultados para os índices de capacidade atlética também lançam dúvidas sobre sua aplicabilidade generalizada em comparações paleobiológicas.
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Camp, Jessica Amber. "Morphological variation and disparity in Lystrosaurus (Therapsida: Dicynodontia)." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/650.
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The dicynodont genus Lystrosaurus, a relative of the Kannemeyerids, is one of few terrestrial vertebrate genera which can be found on both sides of the Permian-Triassic (P-T) boundary (Botha and Smith, 2006); indeed, a single species, Lystrosaurus curvatus, is known from both periods. In the Permian, Lystrosaurus was of average abundance relative to other genera. Shortly following the P-T extinction, it drastically increased in abundance until it dominated the faunas it was present in (Botha and Smith, 2006). To date, Lystrosaurus fossils have been found in South Africa, India, Antarctica, China, and Russia (Grine et al., 2006). Abundance, survivorship, and expansive geographic presence give Lystrosaurus extreme potential as a model organism for multiple questions involving ideas such as extinction survivorship, biogeography, and ecology; however, Lystrosaurus has been subject to the practice of an extreme version of "splitter" taxonomy in the past. Here I quantify Lystrosaurus morphology using geometric morphometrics. Chinese Lystrosaurus taxonomy has not been analyzed in light of this. My results show that they are different from Gondwanan Lystrosaurus and represent at least one if not two unique species.
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Gay, Susan Anne. "A Dicynodont fauna from the Permian of Tanzania." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330250.
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Jasinoski, Sandra Christine. "Comparative cranial biomechanics of lystrosaurus and the generalised dicynodont oudenodon." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492469.
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Dicynodonts were a diverse group of herbivorous therapsids from the PermoTriassic. Differences in cranial morphology among the Dicynodontia have been correlated with changes in masticatory function, and hence, dietary preference. Cranial specialisations of Lystrosaurus were hypothesised to have increased the efficiency of its masticatory system relative to generalised Permian dicynodonts. To test this hypothesis, the cranial function of Lystrosaurus is compared with the generalised dicynodont Oudenodon using finite element analysis (FEA), a computational analysis of structural form, in combination with investigations of cranial sutural morphology and bone histology.
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Francischini, Filho Heitor Roberto. "Paleobiologia de Jachaleria Candelariensis Araújo & Gonzaga, 1980 e comentários sobre a termorregulação em dicynodontia." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/94688.
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Dicinodontes (Therapsida: Anomodontia) compreendem os principais herbívoros do intervalo Permiano Médio-Triássico Superior. Algumas de suas características morfofuncionais cranianas têm se mostrado boas adaptações à herbivoria e ao eficiente processamento oral de materiais vegetais, bem como à termorregulação. Dentre estas, a aquisição da propalinia (movimentação ânteroposterior da mandíbula) e a substituição de um aparelho mastigatório com dentes por uma ranfoteca cobrindo boa parte da extremidade anterior do crânio são os mais característicos. Na anatomia corpórea como um todo, a aquisição de uma postura mais ereta (upright), o aumento do tamanho corpóreo e a presença de turbinais são indicativos de que o grupo evoluiu para um padrão de vida mais ativo e, consequentemente, com um maior gasto energético. Neste trabalho, é apresentada uma revisão bibliográfica sobre tais adaptações e uma discussão sobre sua origem e evolução no clado Anomodontia, focando a espécie Jachaleria candelariensis Araújo & Gonzaga, 1980 do Triássico Superior do Rio Grande do Sul, Brasil.Dicynodonts (Therapsida: Anomodontia) comprise the main herbivores of the Middle Permian - Upper Triassic interval. Some of their morphological and functional cranial characteristics revealed to be adaptations to herbivory and efficient oral processing of plant materials, as well thermoregulation. Among these, the acquisition of propaliny (anteroposterior movements of mandible) and the replacement of the teeth by a ramphoteca covering most of the snout are the most characteristic adaptations. Regarding to their overall shape, the acquisition of a more erect (upright) gait, the increase in body size and the presence of turbinals indicate that this group evolved toward a more active lifestyle and, consequently with a most energetic cost. In this dissertation, is presented a bibliographic revision about such adaptations and a discussion about its origin and evolution within Anomodontia, focusing the Upper Triassic Jachaleria candelariensis Araújo & Gonzaga, 1980, from Rio Grande do Sul State, southern Brazil.
Los dicinodontes (Therapsida: Anomodontia) fueron los principales herbívoros durante el intervalo Pérmico Medio - Triásico Tardío. Presentaban varios caracteres morfofuncionales que reflejan adaptaciones al hábito herbívoro, así como a la termoregulación. Entre las más comunes están la adquisición de la propalinía (movimentación antero-posterior de la mandíbula) y la sustitución de un aparato masticatorio con dientes post-caninos por uno con forma de pico cubierto por una ranfoteca. Otros caracteres como la adquisición de una posición mas erecta (upright), aumento de la talla corporal y la presencia de turbinales son indicativos de que el clado evolucionó hacia un patrón de vida mas activo, y consecuentemente, de un mayor consumo de energía. En este trabajo se realizó una revisión bibliográfica de dichas adaptaciones y se discutió sobre su origen y evolución dentro del grupo Anomodontia, con un enfoque en el taxon Jachaleria candelariensis Araújo & Gonzaga, 1980 del Triásico Tardío de Rio Grande do Sul, Brasil.
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Renaut, Alain Joseph. "A re-evaluation of the cranial morphology and taxonomy of the Triassic dicynodont genus Kannemeyeria." Thesis, University of the Witwatersrand, 2000. http://hdl.handle.net/10539/19499.
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The genus Kannemeyeria is one of the most important and distinctive taxa of the Triassic
dicynodonts. It became the first Triassic dicynodont known to science, and thus forms the
benchmark for the comparison of the evolution and morphology of other Triassic
dicynodonts. An understanding of this genus forms an integral part of the biozonation of
the Beaufort Group, and is pivotal in influencing the interpretation of the evolution,
physiology and phylogenetic relationships of the Triassic dicynodonts. This study focuses
on the detailed cranial morphology and relationships of the Kannemeyeria, and uses a
rigorous morphological investigation as the basis for a meaningful elucidation of the
functional and thus physiological aspects of this dicynodont.
The descriptions demonstrate that variations related to the skull size, distortion or naturally
occurring variation within the genus allow for the synonymy of the formerly recognised
species K. latifrons Broom (1898; 1913), K. erithrea Haughton (1915) and K. wilsoni
Broom (1937). This conclusion is further supported by the allometric analysis which
cannot distinguish the variation observed in the holotypes with that occurring naturally
within a growth series. Apart from the large specimen, the other smaller individuals are
accommodated in the genus as different ontogenetic stages of the growth series
represented by K. simocephalus Weithofer (1888). Several allometric variables show
unusual patterns of development, indicating that Kannemeyeria can be subdivided into
ontological classes, as juvenile and adult forms, separated from each other by a particular
level of development. An age-related threshold level is suggested, and considered to
represent an animal reaching sexual maturity. It is consequently proposed that the
Kannemeyeria population was, at an age-related level, subdivided into sexually mature and immature groups but remained ecologically homogeneous.
Both the descriptions and the allometric analysis of the species K. cristarhynchus Keyser
& Cruickshank (1979) clearly indicate that it does not conform to the growth series of K.
simocephalus and thus the differences observed between these two taxa are not constrained to size increases. Consequently, the recognition of the species K. cristarhynchus is considered valid. From the observations of the cranial morphology, tested using an allometric analysis, generic and specific diagnoses are constructed for Kannemeyeria and its two African species. Several features of Kannemeyeria are discussed in a functional context. A corrugated hom-covered snout and large caniniform processes are considered to be associated with defence and posturing behaviour. Several features of the braincase also suggest herding behaviour. Kannemeyeria also has a slightly different occipital musculature arrangement than that proposed for many other dicynodonts. Most Kannemeyeria cranial features are related to its masticatory function. From the analysis of masticatory cycle it is clear that the jaw action is described via a single pivot-point, which in Kannemeyeria approached the original, primitive position of the jaw hinge. The vertical orientation of the articulation and this pivot-point ensured that the muscle action during second phase of mastication produced an upward crushing and grinding action instead of the typical fore-and-aft motion of many other dicynodonts. It also meant that the muscle force was at their maximum, and little or no energy was lost to translation of the moment arm at the jaw articulation. Consequently, the Kannemeyeria masticatory cycle was both highly effective and extremely efficient. The morphology, and resultant physiology, of Kannemeyeria skull is considered to represent the innovative foundation for much of the success of many of the later Triassic dicynodonts.
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Fordyce, Nicholas. "Cold case files : palaeoforensic and taphonomic study of the Mamafura dicynodont from the end permian." Bachelor's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/25794.
Full textAbstract:
Dicynodonts were non-mammalian herbivorous therapsids (mammal-like reptiles) that flourished world-wide during the Permian and Triassic Periods. They are nowhere more abundant than in the rock strata of the Karoo basin in South Afiica. Taphonomy, the transition from biosphere to lithosphere, is of great geological and biological significance and has provided remarkable insight into palaeoenvironments. A partially articulated dicynodont that has been fossilised alongside an unidentified predator tooth shows evidence of predation and is analysed here. The dicynodont is possibly Oudenodon grandis and was most likely drowned after which it was scavenged from by a gorgonopsian predator, Aelurognathus. The fossil is important as it provides further insight into the ecology of the Late Permian and it enhances our taphonomic understanding.
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Bueno, Ana de Oliveira. "Descrição osteo-histológica de elementos fósseis de Dinodontosaurus turpior (Therapsida, Dicynodontia), Mesotriássico do Rio Grande do Sul, Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/142703.
Full textAbstract:
Estudos relacionados à microestrutura óssea de elementos fósseis surgiram no século XVIII, porém começaram a desenvolver-se mais profundamente somente nas últimas décadas. Hoje, a Paleohistologia é uma das áreas mais promissoras dentro da Paleontologia, pois nos possibilita acessar uma série de características do espécime fóssil que complementam nosso conhecimento sobre o animal. Assim como outros clados, os Dicynodontia vêm sendo estudados por esse viés há muito tempo, e hoje conhecemos os padrões ósseos e de crescimento de um grande número de espécies. A presente dissertação traz a descrição ósteo-histológica de alguns elementos fósseis de Dinodontosaurus turpior, uma espécie de dicinodonte de grande porte do Mesotriássico, encontrada em afloramentos da Formação Santa Maria. Os ossos analisados apresentam majoritariamente uma matriz do tipo fibrolamelar, com alguns subtipos da matriz em dois fragmentos, ausência de linhas de crescimento nos espécimes juvenis e presença destas em fragmentos de espécimes adultos, possibilidade de EFS em um fragmento de adulto, reconstrução secundária surgindo apenas em estágios mais avançados e córtex razoavelmente espesso. Tais características não divergem do padrão já descrito para o grupo como um todo, cujas interpretações para a biologia do animal incluem um metabolismo mais acelerado e uma rápida osteogênese, quando comparada com a de terápsidos mais basais.Studies related to bone microstructure of fossil elements started about the 18th century, however, they began to significantly grow only in the past few decades. Today, paleohistology is one of the most promising areas inside paleontology, because permits to access several characteristics of the fossil specimen which complement our knowledge about the animal. As in other clades, Dicynodontia has been studied in this subject for long time, and now we know about bone growth and microstructure patterns in a variety of species. The present study shows a osteohistological description of some fossil elements of Dinodontosaurus turpior, a medium-to-large size dicynodont species from Middle Triassic of Rio Grande do Sul, Brazil, founded in outcrops of the Santa Maria Formation. The bones analyzed present a fibrolamelar type of bone tissue as major matrix, with some subtypes appearing in a couple of fragments. Growth lines are absent in all juvenile fragments, but appears in the adult ones. One of the adult fragments seems to have an EFS. Also, it was observed secondary reconstruction in adult sample and a thick cortex in all slides that RBT can be calculated. All these features were already been observed in the Dicynodontia clade, whose biological interpretations include an accelerated metabolism and rapid osteogenesis, when compared with basal therapsids.
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Boos, Alessandra Daniele da Silva. "Descrição osteológica de um exemplar de Endothiodon (Synapsida, Dicynodontia) proveniente da Serra do Cadeado (Formação Rio Do Rasto, Permiano Superior) e suas implicações bioestratigráficas e paleobiogeográficas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/56321.
Full textAbstract:
A presente dissertação de mestrado apresenta uma descrição detalhada do primeiro dicinodonte reportado para o Permiano da América do Sul. O material (PV 0226) é composto por um crânio parcial e mandíbulas associadas, proveniente da Serra do Cadeado, estado do Paraná, Formação Rio do Rasto. O espécime foi descrito preliminarmente na década de 70 e atribuído ao gênero Endothiodon. Tal classificação implicava em uma correlação direta com algumas das consagradas biozonas do Grupo Beaufort da África do Sul, já que este táxon é encontrado nesse depósito. Assim, o principal objetivo deste trabalho era verificar a identidade taxonômica do material brasileiro, e a partir da confirmação ou da proposição de outra identificação para o espécime, discutir brevemente as implicações bioestratigráficas e paleobiogeográficas da presença deste fóssil no Brasil. O exemplar em questão foi comparado com espécimes de Endothiodon da coleção do American Museum of Natural History, e uma extensa revisão bibliográfica foi realizada para obter informações sobre espécimes depositados em outras instituições. Por fim, o material brasileiro foi confirmado como pertencendo ao táxon Endothiodon, devido à presença de: forame pineal situado em uma bossa, protuberâncias em forma de bulbo localizadas na face antero-lateral dos dentários, bossa situada na margem ventral do jugal, grande número de dentes inseridos na superfície dorso-medial do dentário, sulco do dentário lateral à fileira de dentes na mandíbula, porção mais anterior da mandíbula em forma de um bico curvo e pontiagudo, entre outras características. Entretanto, não foi possível atribuir a este exemplar uma das quatro espécies do gênero, visto que a atual separação das espécies é dada basicamente por diferenças no comprimento do crânio. Esta feição pode refletir meramente o estágio ontogenético dos indivíduos e não diferenças em nível específico, exceto para E. mahalanobisi que aparenta ser uma forma de pequeno porte. Na realidade, outras características (região interorbital larga, presença de sínfise do dentário grácil ou robusta) apontadas como diagnósticas para o táxon são problemáticas e deveriam ser evitadas ou substituídas por outras mais informativas. Além disso, a forma de Endothiodon do Brasil apresenta uma estrutura denominada “dentary table”, recentemente identificada neste gênero. Em relação à bioestratigrafia, as correlações propostas para as faunas de tetrápodes da Formação Rio do Rasto ressaltam a semelhança dessas com associações faunísticas do Meso e Neopermiano da África do Sul e do Leste Europeu. Porém, até o momento, essas correlações são tentativas, pois poucos elementos dessas faunas são conhecidos para o Brasil e sobre estes, faltam informações relativas aos níveis estratigráficos em que foram coletados. Este último fator gera incertezas em relação à contemporaneidade dos fósseis encontrados em uma mesma localidade. Sobre a aparente escassez de vertebrados para esta formação, quando comparada a outros depósitos de mesma idade, esta parece advinda de um artifício de coleta, ou seja, o material conhecido até o momento não reflete a diversidade que essas localidades devem abrigar. O estudo detalhado de PV 0226 resultou em um artigo submetido para publicação em um periódico de cunho paleontológico.The present master´s thesis presents a detailed description of the first dicynodont reported for the Permian of South America. The material (PV 0226) comprises a partial skull and associated lower jaws, collected in the Serra do Cadeado locality, Paraná state, Rio do Rasto Formation. The specimen was described preliminary during the 1970´s and assigned to the genus Endothiodon. This identification implied a direct correlation with some of the well-established biozones of the Beaufort Group, South Africa, since this taxon is found in this deposit. Thus, the main objective of this work was to verify the taxonomic identity of the Brazilian material and based on the confirmation or proposition of another classification for the specimen, to discuss briefly the biostratigraphic and palaeobiogeogrpahic implications of the presence of this fossil in Brazil. The specimen studied herein was compared with Endothiodon material housed in the collections of the American Museum of Natural History, and an extensive review of the literature was carried out in order to collect information about specimens housed in other institutions. Finally, it was confirmed the material from Brazil belongs to Endothiodon, due to the presence of: pineal foramen situated on a boss, prominent bulbous swellings on the anterolateral sides of the dentary, boss situated on the ventral margin of the jugal, extensive number of teeth on the mid-dorsal surface of the dentary, dentary sulcus lateral to the lower teeth row, anterior portion of the lower jaw prolonged into upwardly curved and pointed beak, among other characteristics. However, it was not possible to assign the material to one of the four species of the genus, as the current distinction of them is based mainly on differences in the skull lenghth. This feature may reflect merely the ontogenetic stage of the specimens and not differences at species level (except from E. mahalanobisi, which seems to be a small form). In fact, other characters (wide interorbital region, slender or robust dentary symphysis) pointed as diagnostic for this taxon are problematic and should be avoided or substituted for others more informative. Besides, the Brazilian form of Endothiodon bears a dentary table, recently indentified in this genus. Regarding biostratigraphy, the correlations proposed for the tetrapod faunas of the Rio do Rasto Formation highlight the similarities between these associations and others from the Mid and Late Permian of South Africa and Eastern Europe. But, until now, these correlations are tentative because few elements of these faunas were recovered from Brazil and most of them lack data about the stratigraphic levels from where they were collected. The latter leads to uncertainty concerning the age of the fossils found in the same locality. About the apparent poverty of vertebrates for this formation when compared to other deposits of the same age, it seems to be a collecting artifact, i.e. the amount of material recovered from this formation until the present does not reflect the potential diversity of it. The detailed study of PV 0226 resulted in an article submitted to a palaeontological journal.
Books on the topic "Dicynodontes"
1
King, Gillian. The dicynodonts: A study in palaeobiology. London: Chapman and Hall, 1990.
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2
King, G. M. Life and death in the Permo-Triassic: The fortunes of the dicynodont mammal-like reptiles. Cape Town: Published by the South African Museum, Cape Town, in collaboration with the Royal Society of South Africa, 1990.
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3
King, Gillian. Life and death in the Permo-Triassic: The fortunes of the dicynodont mammal-like reptiles. Cape Town: South African Museum, in collaboration with the Royal Society of South Africa, 1990.
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4
Sullivan, Corwin. Cranial anatomy of the late permian dicynodont dllctodon, and its bearing on aspects of the taxonomy, palaeobiology and phylogenetic relationships of the genus. Ottawa: National Library of Canada, 2000.
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5
King, G. M. Dicynodonts: A study in palaeobiology. Springer, 1989.
Find full textBook chapters on the topic "Dicynodontes"
1
Vega, Cristina Silveira, and Michael W. Maisch. "Pathological Features in Upper Permian and Middle Triassic Dicynodonts (Synapsida, Therapsida)." In Vertebrate Paleobiology and Paleoanthropology, 151–61. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6841-3_9.
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2
Ray, Sanghamitra, Saswati Bandyopadhyay, and Ravi Appana. "Bone Histology of a Kannemeyeriid Dicynodont Wadiasaurus: Palaeobiological Implications." In New Aspects of Mesozoic Biodiversity, 73–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10311-7_5.
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Angielczyk, Kenneth D., Jean-Sébastien Steyer, Christian A. Sidor, Roger M. H. Smith, Robin L. Whatley, and Stephen Tolan. "Permian and Triassic Dicynodont (Therapsida: Anomodontia) Faunas of the Luangwa Basin, Zambia: Taxonomic Update and Implications for Dicynodont Biogeography and Biostratigraphy." In Vertebrate Paleobiology and Paleoanthropology, 93–138. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6841-3_7.
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"dicynodont, n. & adj." In Oxford English Dictionary. 3rd ed. Oxford University Press, 2023. http://dx.doi.org/10.1093/oed/6130417586.
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Kemp, T. S. "3. The origin of mammals." In Mammals: A Very Short Introduction, 34–44. Oxford University Press, 2017. http://dx.doi.org/10.1093/actrade/9780198766940.003.0003.
Full textAbstract:
‘The origin of mammals’ considers the evolutionary history of mammals using the fossil record to chart their developmental progress. It looks at a group of ‘pre-mammals’, the Synapsids—mammal-like reptiles—including pelycosaurs from 320 mya in the Upper Carboniferous. Then came the therapsids from c.260 mya in the Middle Permian, when the world was increasingly arid. Then 250 mya a mass extinction event wiped out over 90 per cent of animals and plants. Miraculously, a few therapsids survived including the burrowing dicynodont called Lystrosaurus and cynodonts that evolved throughout the Triassic and gave rise to mammals. The earliest mammal was a mouse-sized animal called Morganucodon from 200 mya.