A new specimen provides insights into the anatomy of Irajatherium hernandezi, a poorly known probainognathian cynodont from the Late Triassic of southern Brazil.
Anat Rec (Hoboken). 2022 11; 305(11):3113-3132.AR

Abstract

Irajatherium hernandezi is a poorly known non-mammaliaform cynodont from the Late Triassic of southern Brazil. A new specimen of this cynodont was found in recent fieldwork to the type-locality, Sesmaria do Pinhal (Candelária), providing new insights into the anatomy of this mammalian forerunner. This specimen comprises a partial skull preserving the left canine, two left and three right postcanines, and an isolated exoccipital; the left dentary with the canine and postcanines; a fragment of the right dentary; the proximal portion of the left partial humerus; the right scapula; and indeterminate fragments. Based on new material, it is here suggested that I. hernandezi presents: a rostrum broad and short, possibly long as the temporal region; three foramina on the lateral surface of the maxilla, that could correspond to the external openings of the rostral alveolar, infraorbital, and zygomaticofacial canals; a slender zygomatic arch and an absent postorbital bar; a posteriorly wide temporal fossa; a long secondary palate, slightly surpassing the level of the last postcanine tooth; the cerebral hemispheres of the cranial endocast divided by a median sulcus; the scapular blade long and straight, and the postscapular fossa absent in lateral aspect. Finally, I. hernandezi and other tritheledontids were included in a phylogenetic analysis of Eucynodontia. The analysis recovered unresolved relationships for ictidosaurs/tritheledontids, nested within a polytomy with Tritylodontidae and a clade composed by Pseudotherium argentinus, Botucaraitherium belarminoi, Brasilodon quadrangularis, and Mammaliaformes.

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Authors+Show Affiliations

Kerber L

Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polêsine, Brazil. Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil. Museu Paraense Emílio Goeldi, Coordenação de Ciências da Terra e Ecologia, Belém, Brazil.

Martinelli AG

CONICET-Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia', Buenos Aires, Argentina.

Müller RT

Pretto FA

MeSH

AnimalsBrazilFossilsMammalsPhylogenySkull

Pub Type(s)

Journal Article

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

Language

eng

PubMed ID

34779131

Citation

Kerber, Leonardo, et al. "A New Specimen Provides Insights Into the Anatomy of Irajatherium Hernandezi, a Poorly Known Probainognathian Cynodont From the Late Triassic of Southern Brazil." Anatomical Record (Hoboken, N.J. : 2007), vol. 305, no. 11, 2022, pp. 3113-3132.

Kerber L, Martinelli AG, Müller RT, et al. A new specimen provides insights into the anatomy of Irajatherium hernandezi, a poorly known probainognathian cynodont from the Late Triassic of southern Brazil. Anat Rec (Hoboken). 2022;305(11):3113-3132.

Kerber, L., Martinelli, A. G., Müller, R. T., & Pretto, F. A. (2022). A new specimen provides insights into the anatomy of Irajatherium hernandezi, a poorly known probainognathian cynodont from the Late Triassic of southern Brazil. Anatomical Record (Hoboken, N.J. : 2007), 305(11), 3113-3132. https://doi.org/10.1002/ar.24830

Kerber L, et al. A New Specimen Provides Insights Into the Anatomy of Irajatherium Hernandezi, a Poorly Known Probainognathian Cynodont From the Late Triassic of Southern Brazil. Anat Rec (Hoboken). 2022;305(11):3113-3132. PubMed PMID: 34779131.

* Article titles in AMA citation format should be in sentence-case

TY - JOUR T1 - A new specimen provides insights into the anatomy of Irajatherium hernandezi, a poorly known probainognathian cynodont from the Late Triassic of southern Brazil. AU - Kerber,Leonardo, AU - Martinelli,Agustín G, AU - Müller,Rodrigo T, AU - Pretto,Flávio A, Y1 - 2021/12/10/ PY - 2021/10/11/revised PY - 2021/09/13/received PY - 2021/10/13/accepted PY - 2021/11/16/pubmed PY - 2022/10/15/medline PY - 2021/11/15/entrez KW - Candelária Sequence KW - Caturrita Formation KW - Ictidosauria KW - Norian KW - Probainognathia KW - Tritheledontidae KW - micro CT-scan SP - 3113 EP - 3132 JF - Anatomical record (Hoboken, N.J. : 2007) JO - Anat Rec (Hoboken) VL - 305 IS - 11 N2 - Irajatherium hernandezi is a poorly known non-mammaliaform cynodont from the Late Triassic of southern Brazil. A new specimen of this cynodont was found in recent fieldwork to the type-locality, Sesmaria do Pinhal (Candelária), providing new insights into the anatomy of this mammalian forerunner. This specimen comprises a partial skull preserving the left canine, two left and three right postcanines, and an isolated exoccipital; the left dentary with the canine and postcanines; a fragment of the right dentary; the proximal portion of the left partial humerus; the right scapula; and indeterminate fragments. Based on new material, it is here suggested that I. hernandezi presents: a rostrum broad and short, possibly long as the temporal region; three foramina on the lateral surface of the maxilla, that could correspond to the external openings of the rostral alveolar, infraorbital, and zygomaticofacial canals; a slender zygomatic arch and an absent postorbital bar; a posteriorly wide temporal fossa; a long secondary palate, slightly surpassing the level of the last postcanine tooth; the cerebral hemispheres of the cranial endocast divided by a median sulcus; the scapular blade long and straight, and the postscapular fossa absent in lateral aspect. Finally, I. hernandezi and other tritheledontids were included in a phylogenetic analysis of Eucynodontia. The analysis recovered unresolved relationships for ictidosaurs/tritheledontids, nested within a polytomy with Tritylodontidae and a clade composed by Pseudotherium argentinus, Botucaraitherium belarminoi, Brasilodon quadrangularis, and Mammaliaformes. SN - 1932-8494 UR - https://www.unboundmedicine.com/medline/citation/34779131/A_new_specimen_provides_insights_into_the_anatomy_of_Irajatherium_hernandezi_a_poorly_known_probainognathian_cynodont_from_the_Late_Triassic_of_southern_Brazil_ DB - PRIME DP - Unbound Medicine ER -

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A new specimen provides insights into the anatomy of Irajatherium hernandezi, a poorly known probainognathian cynodont from the Late Triassic of southern Brazil.Anat Rec (Hoboken). 2022 11; 305(11):3113-3132.AR