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New information on Riograndia guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) from the Late Triassic of southern Brazil: anatomical and biostratigraphic implications.
An Acad Bras Cienc. 2011 Mar; 83(1):329-54.AA

Abstract

The tritheledontid Riograndia guaibensis was the first cynodont described for the "Caturrita Formation" fauna from the Late Triassic of southern Brazil (Santa Maria 2 Sequence). The type materials did not preserve anatomical information regarding braincase, occiput, basicranium, zygomatic arch, postdentary bones and craniomandibular joint. Here new materials are described and supply the missing information. Riograndia shows a suite of important anatomical features quite derived among the non-mammaliaform eucynodonts, such as the partial closure of the medial orbital wall and braincase, extensive secondary osseous palate, wide primary palate, basicranium with jugular foramen separated from the periphery of fenestra rotunda, narrow zygomatic arch and much reduced postdentary bones. Many of these features constitute synapomorphies shared only with the other members of mammaliamorpha. Thus, the almost complete cranial, mandibular and dental information from the new fossils of Riograndia can bring a significant improve in the understanding of the anatomy and phylogenetic relationships of the tritheledontids and help to elucidate the transformational steps involved in the cynodont-mammal transition. Additionally, Riograndia is a key taxon in refining the "Caturrita Formation" biostratigraphy, enabling the connection of several fossiliferous outcrops that have a rich tetrapod fauna that can be correlated with other Triassic faunas from Gondwana and Laurasia.

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Authors+Show Affiliations

Soares MB
Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS, Brazil. marina.soares@ufrgs.br
Schultz CL
No affiliation info available
Horn BL
No affiliation info available

MeSH

AnimalsBiological EvolutionBrazilDinosaursFossilsPhylogeny

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21437390

Citation

Soares, Marina B., et al. "New Information On Riograndia Guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) From the Late Triassic of Southern Brazil: Anatomical and Biostratigraphic Implications." Anais Da Academia Brasileira De Ciencias, vol. 83, no. 1, 2011, pp. 329-54.
Soares MB, Schultz CL, Horn BL. New information on Riograndia guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) from the Late Triassic of southern Brazil: anatomical and biostratigraphic implications. An Acad Bras Cienc. 2011;83(1):329-54.
Soares, M. B., Schultz, C. L., & Horn, B. L. (2011). New information on Riograndia guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) from the Late Triassic of southern Brazil: anatomical and biostratigraphic implications. Anais Da Academia Brasileira De Ciencias, 83(1), 329-54.
Soares MB, Schultz CL, Horn BL. New Information On Riograndia Guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) From the Late Triassic of Southern Brazil: Anatomical and Biostratigraphic Implications. An Acad Bras Cienc. 2011;83(1):329-54. PubMed PMID: 21437390.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - New information on Riograndia guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) from the Late Triassic of southern Brazil: anatomical and biostratigraphic implications. AU - Soares,Marina B, AU - Schultz,Cesar L, AU - Horn,Bruno L D, PY - 2010/12/20/received PY - 2010/01/24/accepted PY - 2011/3/26/entrez PY - 2011/3/26/pubmed PY - 2011/10/1/medline SP - 329 EP - 54 JF - Anais da Academia Brasileira de Ciencias JO - An Acad Bras Cienc VL - 83 IS - 1 N2 - The tritheledontid Riograndia guaibensis was the first cynodont described for the "Caturrita Formation" fauna from the Late Triassic of southern Brazil (Santa Maria 2 Sequence). The type materials did not preserve anatomical information regarding braincase, occiput, basicranium, zygomatic arch, postdentary bones and craniomandibular joint. Here new materials are described and supply the missing information. Riograndia shows a suite of important anatomical features quite derived among the non-mammaliaform eucynodonts, such as the partial closure of the medial orbital wall and braincase, extensive secondary osseous palate, wide primary palate, basicranium with jugular foramen separated from the periphery of fenestra rotunda, narrow zygomatic arch and much reduced postdentary bones. Many of these features constitute synapomorphies shared only with the other members of mammaliamorpha. Thus, the almost complete cranial, mandibular and dental information from the new fossils of Riograndia can bring a significant improve in the understanding of the anatomy and phylogenetic relationships of the tritheledontids and help to elucidate the transformational steps involved in the cynodont-mammal transition. Additionally, Riograndia is a key taxon in refining the "Caturrita Formation" biostratigraphy, enabling the connection of several fossiliferous outcrops that have a rich tetrapod fauna that can be correlated with other Triassic faunas from Gondwana and Laurasia. SN - 1678-2690 UR - https://www.unboundmedicine.com/medline/citation/21437390/New_information_on_Riograndia_guaibensis_Bonaparte_Ferigolo_&_Ribeiro_2001__Eucynodontia_Tritheledontidae__from_the_Late_Triassic_of_southern_Brazil:_anatomical_and_biostratigraphic_implications_ L2 - https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000100021&lng=en&nrm=iso&tlng=en DB - PRIME DP - Unbound Medicine ER -