New and old materiales of the Middle-Late Triassic Pseudosuchian Prestosuchus chiniquensis and the validity of ?Prestosuchusuchidae

M. BELÉN VON BACZKO; J.B. DESOJO; RAUHUT, O.W.

Bruselas

Congreso; 17th Conference of the European Association of Vertebrate Palaeontology, Bruselas.; 2019

The largest predators of Triassic continental ecosystems were represented by the ill-defined group?Rauisuchia?. One of the earliest described members of the group was Prestosuchus chiniquensis,from the Santa Maria Supersequence (Brazil), which thus became a reference taxon for ?Rauisuchia?for being one of the best preserved and more complete specimens at that time. Although newspecimens have recently been referred to this taxon, the original type material has received littleattention since its first description, and needs further scrutiny.The lectotype of Prestosuchus chiniquensis includes cranial fragments, partial articulated mandibles,some cervical, dorsal, sacral and caudal vertebrae and rib fragments, gastralia, complete andarticulated pectoral girdle, partial humeri, partial pelvic girdle, and hindlimb. The taxon can bediagnosed by two autapomorphies, the presence of an oval incision in the coracoid-scapula sutureand a small distal incision between the obturator plate and the ischial shaft, and a unique combinationof non-autapomorphic characters. Based on this diagnosis, several other specimens can beconfidently referred to Prestosuchus chiniquensis, including the paralectotype (BSPG-AS-XXV 7), theparalectotype of Prestosuchus loricatus (BSPG-AS-XXV 24, 25, 42, 4), the holotype of Procerosuchusceler (BSPG-AS-XXV 131-139), and several posteriorly referred specimens (UFRGS-PV-152, 156,629, CPEZ-239b, ULBRA-PVT-281), including complete crania and large parts of the postcranialskeleton. These materials make Prestosuchus chiniquensis one of the best-known ?rauisuchians? andprovide a wealth of anatomical information for phylogenetic analysis in order to clarify the affinities ofbasal loricatans, such as Prestosuchus, Luperosuchus, Saurosuchus, Stagonosuchus, andFasolasuchus, re-evaluating the validity of ?Prestosuchidae?.