SKULL PERFORMANCE DIFFERENCES BETWEEN NOTOSUCHIANS AND CROCODYLIDS

MAURO NICOLAS NIETO; FEDERICO JAVIER DEGRANGE; KALEB C. SELLERS; DIEGO POL; CASEY M. HOLLIDAY

Mendoza

Jornada; 34 Jornadas Argentinas de Paleontología de Vertebrados; 2021

In this work, we present a comparative analysis between Araripesuchus gomesii, a small notosuchian from the Early Cretaceous of Brazil, and Alligator mississippiensis, a living representative of the crocodyliform lineage considered as a model species for herpetological and functional studies. A finite element analysis (FEA), comparing the skull performance of both species, was carried out based on 3D models reconstructed from CT scans and using published bone properties for crocodiles. The adductor musculature attachments areas were reconstructed using extant phylogenetic bracket (EPB), and muscle forces were calculated. The two taxa were scaled to the same volume. Different biting scenarios were tested for both species: unilateral bite, bilateral bite, pullback, head-shake and head-twist. In the different simulations, the skull and lower jaws of Araripesuchus suffers more stress in the head-shake movement, followed by the unilateral and pullback bites with the stress focalized in the premaxillary region, whereas the head-twist is the simulation with smaller stress values recorded. A. mississippiensis shows superficially a similar stress distribution pattern, but with higher values, being the most anterior unilateral bite the simulation with higher stress recorded. Araripesuchus provides an interesting intermediate stage in the crocodyliform lineage, in which the antorbital fenestra is still present, but the secondary palate is incipiently developed. Similar to what was concluded in different studies, the oreinirostral snout of Araripesuchus seems to provide greater resistance during feeding than the platyrostral snout of A. mississippiensis, despite presenting an antorbital fenestra, which would represent a zone of ?weakness? in the skull.