New and old materials of the Middle-Late Triassic pseudosuchian Prestosuchus chiniquensis and the validity of ?Prestosuchidae?

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

Bruselas

Congreso; XVII Conference of the European Association of Vertebrate Palaeontologists; 2019

Royal Belgian Institute of Natural Sciences

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 new specimens have recently been referred to this taxon, the original type material has received little attention 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 and articulated pectoral girdle, partial humeri, partial pelvic girdle, and hindlimb. The taxon can be diagnosed by two autapomorphies, the presence of an oval incision in the coracoid-scapula suture and a small distal incision between the obturator plate and the ischial shaft, and a unique combination of non-autapomorphic characters. Based on this diagnosis, several other specimens can be confidently referred to Prestosuchus chiniquensis, including the paralectotype (BSPG-AS-XXV 7), the paralectotype of Prestosuchus loricatus (BSPG-AS-XXV 24, 25, 42, 4), the holotype of Procerosuchus celer (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 postcranial skeleton. These materials make Prestosuchus chiniquensis one of the best-known ?rauisuchians? and provide a wealth of anatomical information for phylogenetic analysis in order to clarify the affinities of basal loricatans, such as Prestosuchus, Luperosuchus, Saurosuchus, Stagonosuchus, and Fasolasuchus, re-evaluating the validity of ?Prestosuchidae?.