A MORPHOMETRIC AND KINETIC ANALYSIS OF THE DEVELOPMENT OF THE FEEDING APPARATUS OF MONODELPHIS DOMESTICA

by Thompson, Elicia N.

While juvenile and adult mammals must overcome similar challenges in order to survive, these must be accomplished with very different tools and strategies. Using Monodelphis domestica ontogeny of masticatory mechanics was examined. Under the framework of the constrained model of jaw biomechanics, linear measurements were used to describe age-dependent changes in shape and mechanical advantage of the jaws. Additionally, bite force data were collected from both juveniles and adults. Both age categories maintained similar numbers of molariform teeth within the jaw. However, because of improved mechanical advantage, adults produced absolutely greater bite forces with these teeth. By contrast, juveniles produced relatively greater bite forces, powered by relatively larger resultant muscle forces. Therefore, ontogenetically-determined size and shape differences between juveniles and adults have large affects on the biomechanical properties of opossum jaws. Juveniles can produce relatively high bite forces for their body size, but these bite forces require greater energy expenditures.