Postcranial anatomy of Prestosuchus chiniquensis (Archosauria: Loricata) from the Triassic of Brazil

Abstract

Prestosuchus chiniquensis is the best represented pseudosuchian archosaur fromthe Pinheiros-Chiniqua Sequence, Middle-Late Triassic (Ladinian/Carnian) of theSanta Maria Supersequence, Southern Brazil. Several incomplete specimens attributedto this species have been described, but the morphology of the postcranialskeleton of P. chiniquensis is poorly known. In this contribution we present thepostcranial material of the UFRGS-PV-0629-T specimen, concluding its description,as its skull and endocast have already been described. Additionally, histologicaldata provided new information on the poorly known ontogenetic series ofP. chiniquensis, and on its growth patterns suggesting a longer period of slowgrowth when compared to other basal Loricata species. A phylogenetic analysisplaced UFRGS-PV-0629-T in a group composed by the lectotype, paralectotype,and other described P. chiniquensis specimens, further corroborating our taxonomichypothesis, that specimens of basal Loricata collected in Brazil are closelyrelated to each other. Due to the association of characters found in the phylogeneticanalysis, the specimen UFRGS-PV-0629-T is attributed as the most completematerial ever found for P. chiniquensis. As such, it is clear that the material presentedhere provides important new information on P. chiniquensis. Based on theresults presented here, we revised the diagnosis for P. chiniquensis. However, italso evidences the need for new discoveries and studies of other specimens seekingto understand this and other closely related species, which were important componentsof worldwide trophic webs of the Triassic biotas.