COMPARING CONSISTENCY OF PROXIES FOR BITE-FORCE ESTIMATES ACROSS MULTIPLE TAXA

Feeding traces on bones can be used to determine information about the morphology and trophic interactions of extinct animals. By simulating these feeding traces, further information on feeding strategy and even estimations of bite force can be quantified. However, modern analogs for experimentally replicating such fossilized traces are limited. Using readily available fresh bone samples as analogs is efficient, but it is unknown if the relationship between cortical bone thickness and bite force required for indentation is consistent across tetrapods or differs systematically due to variations in bone microstructure. By comparing the forces required to indent samples replicated across bones with distinct histological organizations but using the same indenter, we tested the effect of modern analog selection on load variation and trace reproducibility. Controlling a nickel alloy model of a maxillary tooth from a known bone-indenting taxon, namely adult Deinonychus antirrhopus, within a mechanical loading frame, we performed experimental indentations into femora from three disparate modern exemplars: Odocoileus virginianus, Alligator mississippiensis, and Dromaius novaehollandiae. After recording the force needed to indent multiples of each, the bones were sawed across indentation sites, allowing measurements of cortical bone thickness at the point of each simulation. The relationship between average cortical bone thickness of the indented area and indentation force (i.e., simulated bite force) was then compared across taxa. Individual regressions within each taxon yielded only moderate r² values, but an ANCOVA, comparing them yields insignificant results. Notably, a sample including larger exemplars of A. mississippiensis may help clarify patterns within this taxon in particular. Nonetheless, our results suggest that, after taking cortical bone thickness into account, analogs of disparate taxa accurately report comparable bite forces. This suggests that differences in bone microstructure do not meaningfully impact the resistance to indentation on a macro-anatomical scale using engineering simulations.