DUMONT, E.R*; PICCIRILLO, J.; GROSSE, I.R.; University of Massachusetts at Amherst; University of Massachusetts at Amherst; University of Massachusetts at Amherst: Morphology meets engineering: Finite element analyses of biting behavior in bats

Field-based studies of feeding behavior in mammals demonstrate that mammals with similar ecological niches and craniofacial morphologies often use significantly different biting styles during feeding. These styles vary with respect to the magnitude and type of load (bending or twisting) applied to the skull. The mismatch between cranial morphology and loading regime raises the question, is there a relationship between biting behavior and skull shape? To answer this question we compared bone stress and strain during typical and atypical biting behaviors in two ecologically and morphologically convergent bats, Artibeus jamaicensis (F. Phyllostomidae) and Cynopterus brachyotis (F. Pteropodidae). To generate a global view of stress and strain during biting, we turned to finite element analysis – a numerical technique used routinely by engineers to predict the behavior of physical systems. We developed a detailed 3D finite element model of a skull from each species using 2D micro-CT scans. Initially, we applied estimates of the forces exerted by the temporalis and masseter muscles to the models. After this initial analysis, the muscle forces were adjusted such that known bite reaction forces were reproduced. Bite forces and joint reaction forces were solved automatically by constraining the models at the appropriate points. Comparisons indicate that atypical loading patterns often result in higher stress and strain than do routine loading regimes. Despite similarities in skull shape between the two species of bats we studied, the subtle morphological differences between them appear to minimize the biomechanical impact of their different biting styles.