COMPARING PROXIES IN BITE-FORCE ESTIMATES BASED ON EXPERIMENTALLY REPLICATED BITE MARKS

Bone surface modification by carnivores and scavengers on animal remains can provide key insights into the trophic relationships and behavior of extinct organisms. Carnivores and scavengers exhibit wide variations in dentition, which are visible in feeding damage on bone surfaces. Bone modulus is pleisiomorphic for tetrapods and microstructural features are shared among widely divergent groups such as artiodactyls and ornithischian dinosaurs. As a result, some tooth traces can be used to estimate ancient bite forces using living bone. These estimates can, in turn, offer insights about the anatomy and performance of the predators themselves as well as on trophic interactions in the fossil record. To explore the relationship between bite marks and bite force, we tested the effects of a simulated Deinonychus antirrhopus bite on white-tail deer femora, a proxy for Tenontosaurus long bones. Femora are composed of trabecular and cortical bone, which varies predictably from articular surface to diaphysis. Using a mechanical loading frame, a nickel-alloy replica of a large adult D. antirrhopus maxillary tooth, and fresh deer bone, we tested: (1) how much force was necessary to puncture a femur at various points along its length, (2) if indentation force varied predictably by location, and (3) whether the thickness of the cortical bone influenced the required force. The results of this analysis then would be compared to a similar set of simulations using cow bone as a proxy. In general, our results show that the force needed to indent deer bone correlated positively with cortical thickness across indentation locations, we also found that indentation force was lower for cortical bone at the proximal than distal ends of long bones. Overall, these results were largely consistent with the results of previous indentation simulations of cow bone, given expected variation related to cortical bone thickness. This analysis quantitatively characterizes previously recognized taphonomic patterns related to density mediated attrition and density-linked bone surface modifications. In the future, we plan to compare these results to simulations performed on avian and crocodylian bones, in order to further explore the effects of proxy selection on indentation simulation estimates.