Proterochampsia: an endemic archosauriform clade from South America

Proterochampsia is a monophyletic group of crocodile-like archosauriforms currently endemic to the late Middle and early Late Triassic of South America considered as one of the potential successive sister-taxa of the crown group Archosauria. The proterochampsians come from the Ischigualasto-Villa Unión Basin in the west of Argentina and the Parana Basin in the south of Brazil. The traditional composition of the group includes the genera Cerritosaurus Price 1946 , Proterochampsa Reig 1959 (with two species: P . barrionuevoi in Argentina and P. nodosa Barberena 1982 in Brazil), Chanaresuchus Romer (with two species from Argentina: C. bonapartei Romer and C. ischigualastensis Trotteyn et al. 2012 ), Gualosuchus reigi Romer 1971 and Tropidosuchus romeri Arcucci 1990 . After a precladistic history of confusion about their relationships with crocodilians, in the last 20 years new discoveries of taxa, and more systematic and phylogenetic studies, have clarified their position as non-archosaurian archosauriforms and their relationships with other Triassic archosaurs.