VAN VALKENBURGH, B; SACCO, T; WANG, X; Univ. of California, Los Angeles; Univ. of California, Los Angeles; Natural History Museum of Los Angeles County: Recognizing Pack Hunters in the Fossil Record: Evidence from Craniodental Morphology and Body Size

The Borophaginae is the largest of the three subfamilies of the dog family Canidae, including some 66 species that span approximately 34 million years (Orellan to Blancan). Here we examine possible foraging modes within the Borophaginae using morphometrics and two new approaches to estimating the typical prey size of extinct carnivores. Prey size is estimated for the borophagines based on the positive correlation between dentary height and typical prey size in living canids. These results are compared with those produced using a published energetic model that predicts that all carnivores larger than about 21 kg feed on prey as large or larger than themselves. Both methods produce similar predictions, resulting in a list of 11 species of Borophaginae that probably consumed prey as large or larger than themselves. Moreover, we suggest that five of these species probably hunted in groups frequently because of the need to act together to pull down very large prey. Previous workers have argued that most or all borophagines were scavengers rather than hunters based on heavy dental wear and robust skeletal morphology. Neither of these precludes hunting in our view. Sharp teeth are not a requirement for making a kill, as the well worn and broken teeth of many extant carnivorans demonstrates. Although the limb morphology and skeletal proportions of most or all borophagines do not appear to have adapted for long distance chases, high speed pursuits over shorter distances would have been possible. The recognition of large borophagines as hunters rather than scavengers increases their relevance for studies of predator-prey coevolution.