Meeting Abstract

S9-2.4  Jan. 6  Evolution of Feeding Morphologies in the Carnivora VAN VALKENBURGH, Blaire; Univ. of California, Los Angeles

The fossil record of the order Carnivora extends back at least 56 million years, and documents a remarkable history of adaptive radiation, characterized by the repeated, independent evolution of similar feeding morphologies in distinct clades. Within the order, convergence is apparent in the iterative appearance of a variety of ecomorphs, including short-faced “cats” (felids, canids, mustelids, herpestids), bone-cracking hypercarnivores (canids, hyaenids), sabertooth “cats” (nimravids, felids) and frugivorous omnivores (procyonids, canids, viverrids). The iteration of similar forms has multiple causes. First, there are a limited number of ways to ecologically partition the predominant resource, vertebrate prey. Moreover, the material properties of animal tissues have not changed over the Cenozoic, and consequently, similar craniodental adaptations for processing skin, muscle, and bone evolve again and again. The extent of convergence in craniodental form can be striking, affecting skull proportions and overall shape, as well as dental morphology. This tendency to evolve highly convergent ecomorphs is most apparent among feeding extremes, such as sabertooths and bone-crackers where performance requirements tend to be more acute. Finally, the iterative evolution of large-bodied, highly carnivorous species in multiple families results from a combination of ecological (intra- and interspecific competition) and physiological (foraging energetics) constraints that ultimately lead to increased vulnerability to extinction of formerly successful clades. Thus, large hypercarnivores have evolved in rough succession with the decline of one clade followed by the rise of another, contributing to the overall pattern of repeated convergence within the order.