New insights in “rauisuchian “taxa (Archosauria: Crurotarsi) from Brazil

DESOJO, J. B.; RAUHUT, O.W.

Dublind, Irlanda

Simposio; Symposium of Vertebrate Palaeontology and Comparative Anatomy Annual Meeting; 2008

National Museum of Irland

Rauisuchian archosaurs were some of the largest terrestrial carnivores during the Middle and Late Triassic in Europe, North Africa, India, Asia, and the Americas. However, despite their worldwide distribution, rauisuchian evolutionary history is poorly understood and their taxonomy remains problematic because many taxa were erected on fragmentary, undiagnostic remains. This is especially the case for the taxonomy of rauisuchian remains from Brazil (Santa Maria Supersecuence) described by Huene (1942). An anatomical revision of these materials confirms the rauisuchian nature and validity of Prestosuchus chiniquensis (diagnosable by eg. anterior notch between the scapula and coracoid, longitudinal ridge on the dorsal surface of the ischium). “P”. loricatus is also a valid species of rauisuchian, but differs in several characters from Prestosuchus (triangular neural spine of cervical vertebra in lateral view, accessory processes on caudal vertebrae, pit on the posterior head of the ischium), and thus represents a distinct genus. The Paralectotype of P. loricatus is referable to P. chiniquensis (eg. calcaneal tuber as height as wide and ventral surface with a depth pit), and we confirm the assignation of the paralectotype of P. chiniquensis to this species (contra Kirschlat, 2000). Procerosuchus is a juvenile specimen of P. chiniquensis and Rhadinosuchus is a juvenile specimen of Proterochampsidae, as was previously suggested by some authors. Hoplitosuchus is a nomen dubium, the type of which consists of unidentifiable bones, while the referred material includes remains of a rauisuchian and a dinosaur. These data confirm the presence of at least 3 genera (including Rauisuchus) of rauisuchian in the Middle Triassic of Brazil.