MAMMALIAN RESPONSES TO CLIMATE CHANGE DURING THE LATE PLEISTOCENE IN SOUTHERN CALIFORNIA: LESSONS LEARNED FROM THE SURVIVORS OF THE LATE PLEISTOCENE MEGAFAUNAL EXTINCTION

The La Brea Tar Pits in southern California contains more fossil carnivorans than anywhere else on the globe with most fossils deposited approximately 40,000 to 11,000 years before present. Understanding if and how smaller surviving canids and felids responded to the megafaunal extinction is important to testing mesopredator release hypotheses and assessing biotic responses to the loss of apex predators, today. The degree to which carnivans consumed flesh (tougher food) or bone (harder food) and the habitats occupied by prey (closed verse more open) were assessed using dental microwear texture analysis (DMTA) and stable isotope analyses, respectively. While isotopic differences between pits and among felids or canids were largely not significantly different through time or as compared to like taxonomic groups (e.g., felids compared to one another), dental microwear texture analysis revealed distinct dietary differences. Coyotes consume softer foods during the Late Pleistocene, yet have nearly identical and indistinguishable dental microwear to dire wolves when occurring in southern California, today - suggesting a shift towards increased carcass utilization with the local absence of wolves. In contrast, cougars had highly opportunistic diets both today and in the past and engaged in some scavenging during both the Pleistocene and today - with "less picky" eating as a potential key to success. Further, all felids specialized on prey largely consuming C₃ resources, likely in forested environments; this is in contrast to the dire wolf which largely ate prey in more open environments. While both coyotes and cougars are highly adaptable today and may have been more resilient to changing climates and biotic communities due to their consumption of smaller prey, their dietary ecology was disparate in regards to scavenging and prey-resources consumed during the Pleistocene.