The skull anatomy and cranial endocast of Prestosuchus chiniquensis (Archosauria: Pseudosuchia) from Brazil.

MASTRANTONIO, B; VON BACZKO, M. BELEN; DESOJO, JULIA BRENDA; CESAR LEANDRO SCHULTZE

ACTA PALAEONTOLOGICA POLONICA

INST PALEOBIOLOGII PAN

Lugar: Varsovia; Año: 2018 vol. 64

0567-7920

Prestosuchus chiniquensis is the most famous ?rauisuchian? described by Friedrich von Huene, eight decadesago, and several specimens have been assigned to this taxon since then. In the present contribution, we providethe first detailed description of a complete and very well preserved skull (including the braincase, preliminarlydescribed in Mastrantonio et al., 2013) assigned to Prestosuchus chiniquensis from the DinodontosaurusAssemblage Zone of the Santa Maria Supersequence of southern Brazil. The detailed description of the skull ofPrestosuchus chiniquensis, besides increasing the knowledge about this taxon, may help elucidate thetaxonomic relationships of pseudosuchians even further, since most of the characters used in phylogeneticanalyzes are cranial. The presence of the subnarial fenestra, a controvertial extra opening on the skull of?rauisuchians?, is thoroughly discussed considering the evidence provided by this new specimen. We considerthat the small slit-opening between the premaxilla and the maxilla in Prestosuchus chiniquensis, can not safelybe considered a true fenestra, but indicates more likely the existence of some degree of cranial kinesis betweenthese elements which can result in different relative positions of the bones after definitive burial andfossilization, so that the size and shape of this opening is taphonomically controlled. Complementarily, thedigital reconstruction of its cranial endocast was developed both from the observation of the preservedbraincase and from CT scan images, which resulted in obtaining the first endocast known for a ?rauisuchian?.The endocast of Prestosuchus chiniquensis exhibited some remarkable convergences with that of theropoddinosaurs, which could be a reflection of the similar niches they occupied, since ?rauisuchians? were the toppredators at the end of the Late Triassic, before the extinction of all non-crocodylomorph pseudosuchians.