First biomechanical analysis on the skull of the ornithosuchid Riojasuchus tenuisceps Bonaparte 1967 from the Los Colorados Formation, Late Triassic of Argentina

VON BACZKO, M.B.; TABORDA, J.R.A.; DESOJO, J.B.

Zapala, Neuquen

Jornada; XXVIII Jornadas Argentinas de Paleontologia de Vertebrados; 2014

Museo Provincial de Ciencias Naturales Prof. Juan Olsacher

Riojasuchus tenuisceps Bonaparte 1967 is a terrestrial quadrupedal archosaur from the Late Triassic. It has a triangular-shaped skull with a ventrally curved snout, and posteriorly curved serrated teeth. Although it has been assumed that ornithosuchids had animalivorous feeding habits based on morphological features, no functional study has been carried out to test its type of animalivory (carnivorous or scavenging). R. tenuisceps has a very well anteroventrally expanded and laterally constricted snout; the holotype (PVL 3827) comprises a complete skull that allowed us to study the problematic of its feeding habits. We developed a virtual 3D model of the skull of the holotype using CT scan, and generated a Finite Elements Model of it, applying anteroposterior and lateral forces on the weird snout of R. tenuisceps, simulating some basic efforts during its feeding. We tested the response of the modeled skull using Finite Elements Analysis, obtaining that the snout of R. tenuisceps had a high resistance to anteroposterior dragging (around 75kg), but when applying lateral forces to the snout it was much weaker and would endure approximately 25kg. Considering the resistance of this structure, we propose that R. tenuisceps could have been carnivorous, hunting small to medium size live preys, and even drag larger carcasses. We conclude that R. tenuisceps could have had both carnivore and scavenging habits depending on the size of the chosen prey, needing a different strategy to overthrow its larger victims avoiding strong lateral stresses that may occur when a prey tries to escape