Biomechanical skull performance in the meiolaniid Niolamia argentina (Testudinata: Meiolaniidae) using Finite Element Analysis

Abstract

The use of horns and frills for sexual display and attack has been proposed and demonstrated in extinct taxa on several occasions, with the ceratopsian dinosaurs as the most iconic example. Niolamia argentina is a large meiolaniid turtle from Patagonia, characterized by the presence of extensive frills and massive horns in the skull. Here, Finite Element Analysis (FEA) is applied in the only known adult skull of N. argentina to assess the cranial performance simulating defensive/aggressive movements. We tested five different scenarios: (1) hitting with the snout, (2) hitting with the forehead, (3) struggling with the notch between the frill and the horn, (4) stabbing with lateral horns, and (5) caudal torsion of the frills, the last two being the most damaging and stressful scenarios. Together with the lack of skull features related to head-hitting/fighting, we find that, although the cranial structures of Niolamia argentina studied here may indicate a priori that they were for engaging in combat between males, hitting each other with the caudal frills and trying to stab each other may represent highly stressful scenarios. In this sense, we propose that the presence of frills and horns in N. argentina seems to be more suitable for sexual display than for combat behavior.