Meeting Abstract

75.2  Friday, Jan. 6  Assessing biomechanical performance in extinct crocodylians: a neontological model of bite-force generation and tooth pressures in fossil forms GIGNAC, P.M.*; ERICKSON, G.M.; Stony Brook University; Florida State University paul.gignac@stonybrook.edu

Crocodylians have dominated predatory niches at the water-land interface for over 85 million years. Like their ancestors, living species show substantial variation in their body sizes, jaw proportions, and dental forms, the latter of which stand in contrast to their strongly conserved post-cranial anatomy. As a result, it is thought that variation in crocodylian dental, cranial, and musculoskeletal characters has tracked available niche space within a narrow range of ecomorphology and has been the driving engine of their diversification. One critical aspect to understanding the evolution of this feeding system is its biomechanical performance in living and fossil forms. However, the ecological and evolutionary import of feeding capacities such as bite forces and tooth pressures has remained elusive. Two recent studies focusing on the development and diversification of bite forces and tooth pressures in living taxa have shed new light on this issue. Here we add to these advancements with a recently developed mathematical model of the crocodylian jaw-adductor system, which can be used to assess biomechanical performance in the crocodylian fossil record. We validated the bite-force model by testing it against a diversity of known-bite-force, adult crocodylians and showed that we can accurately predict these values. We then derived jaw-muscle reconstructions for extinct crocodylian taxa and, along with measurements of their dental form, produced bite-force and tooth-pressure estimates. These were also successfully tested against our performance data from extant taxa. Together insights from these developmental, evolutionary, and paleontological analyses now make it possible to address further questions about crocodylian evolutionary niche transitions and the mechanisms of their subsequent diversification.