Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae) from the Early Late Triassic Ischigualasto Formation of Northwestern Argentina

TROTTEYN, M. J.; EZCURRA, M. D.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2014 vol. 9

1932-6203

Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedalarchosauriforms characterized by an elongated and dorsoventrally low skull. Thegroup is endemic from the Middle-Late Triassic of South America. The mostrecently erected proterochampsid species is ??Chanaresuchus ischigualastensis??,based on a single, fairly complete skeleton from the early Late TriassicIschigualasto Formation of northwestern Argentina. We describe here in detail thenon-braincase cranial and postcranial anatomy of this species and revisit itstaxonomy and phylogenetic relationships. The phylogenetic analysis recovered?Chanaresuchus ischigualastensis? as part of a trichotomy together withGualosuchus reigi and Chanaresuchus bonapartei. Accordingly, ??Chanaresuchusischigualastensis?? can be potentially more closely related to Gualosuchus reigi, oreven Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, afterdiscussing previously claimed synapomorphies of Chanaresuchus, we could notfind unambiguous support for the monophyly of the genus. As a result, we proposehere the erection of the new genus Pseudochampsa for ?Chanaresuchusischigualastensis?, which results in the new combination Pseudochampsaischigualastensis. The information provided here about the anatomy and taxonomyof Pseudochampsa ischiguaslastensis will be useful for future quantitative analysesfocused on the biogeography and macroevolutionary history of proterochampsids.