USING DENTAL MICROWEAR TEXTURES TO RECONSTRUCT FEEDING ECOLOGY OF BEARS

Dramatic environmental changes associated with Pliocene cooling and the onset of glacial-interglacial cycles in the Pleistocene served as a backdrop to the evolutionary radiation of modern bears. These environmental changes likely triggered changing food availabilities, and adaptations to new diets that become an important underlying mechanism in ursid evolution. Here, we report how dental microwear textures relate to diet for extant ursids and apply results to extinct Arctodus pristinus and Tremarctos floridanus from Florida, and Agriotherium africanum from South Africa. Lower first and second molars (m1 and m2, respectively) were analyzed for the carnivorous/omnivorous polar bear (Ursus maritimus), omnivorous American black bear (Ursus americanus), herbivorous/omnivorous spectacled bear (Tremarctos ornatus), specialist bamboo consuming giant panda (Ailuropoda melanoleuca), and the three fossil taxa. Significant variation along the tooth row is consistent with functional differentiation wherein the m2 processes harder objects than the m1. Results evince significant variation among species: carnivorous/omnivorous taxa (U. maritimus, U. americanus) have significantly higher complexity (Asfc) than more herbivorous ones (T. ornatus, A. melanoleuca), and A. melanoleuca has higher anisotropy (epLsar) as expected given the fracture properties of their reported diets. Further, A. pristinus, T. floridanus and A. africanum exhibit significantly higher complexity and texture fill volume (Tfv) than extant taxa, suggesting more hard-object consumption in these fossil species.