Meeting Abstract
Reconstructing feeding behavior for extinct taxa typically relies on comparisons to living relatives. However, this is problematic when studying fossils with ambiguous phylogenetic affinities. In the early Paleogene, several faunivores with unclear evolutionary relationships exploited prey with different physical properties. Here we use a biomechanical approach and apply beam theory to determine the cross-sectional properties of dentaries, assessing the capacity of these taxa to process tougher versus more ductile foods. Micro-CT scans were prepared for 20 dentaries comprising four orders of early Paleogene taxa from North America. For each specimen, the dimensions of the dentary were measured at homologous slices along the tooth row to calculate section moduli (geometric properties of beams) using the BoneJ plugin to ImageJ. Some fossil carnivorans and creodonts were found to overlap in range for mean dorsoventral section moduli with small extant canids, suggesting that they are equally resistant to dorsoventral bending during prey capture and processing. In addition, different genera within the Pantolestidae are differentially resistant to bending stresses, supporting previous hypotheses of pantolestid feeding behavior based on comparative tooth morphology. The biomechanical properties of the dentary are independent of phylogeny and reflect bone remodelling in response to forces encountered during life. Thus, they can be used in conjunction with other lines of evidence to develop more explicitly testable hypotheses about behavior in extinct organisms and create more informed reconstructions of feeding behavior.
