Earth and Environmental Science Transactions of the Royal Society of Edinburgh

Research Article

Cranial anatomy of a new genus of hyperodapedontine rhynchosaur (Diapsida, Archosauromorpha) from the Upper Triassic of southern Brazil

Felipe Chinaglia Montefeltroa1, Max Cardoso Langera1 and Cesar Leandro Schultza2

a1 Laboratório de Paleontologia, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 14040-901, Ribeirão Preto SP, Brazil Email: felipecm@pg.ffclrp.usp.br; mclanger@ffclrp.usp.br

a2 Departamento de Paleontologia e Estratigrafia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91540-000 Porto Alegre RS, Brazil Email: cesar.schultz@ufrgs.br

ABSTRACT

Detailed description of the cranial anatomy of the rhynchosaur previously known as Scaphonyx sulcognathus allows its assignment to a new genus Teyumbaita. Two nearly complete skulls and a partial skull have been referred to the taxon, all of which come from the lower part of the Caturrita Formation, Upper Triassic of Rio Grande do Sul, southern Brazil. Cranial autapomorphies of Teyumbaita sulcognathus include anterior margin of nasal concave at midline, prefrontal separated from the ascending process of the maxilla, palatal ramus of pterygoid expanded laterally within palatines, dorsal surface of exoccipital markedly depressed, a single tooth lingually displaced from the main medial tooth-bearing area of the maxilla, and a number of other characters (such as skull broader than long; a protruding orbital anterior margin; anguli oris extending to anterior ramus of the jugal; bar between the orbit and the lower temporal fenestra wider than 0·4 of the total orbital opening; mandibular depth reaching more than 25 of the total length) support its inclusion in Hyperodapedontinae. T. sulcognathus is the only potential Norian rhynchosaur, suggesting that the group survived the end-Carnian extinction event.

Key Words:

  • Caturrita Formation;
  • Norian;
  • Rhynchosauria;
  • skull anatomy;
  • Teyumbaita sulcognathus