DISSERTATION RESEARCH: Carnivory in the Oligo-Miocene: Dietary community ecology and diversity dynamics of large mammalian predators

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Competition is a common explanation for why carnivorous mammals differ in ecology, structure, and function. Over long time scales, it may also explain how current carnivore communities assembled. Dogs (wolves, jackals, foxes, coyotes, domestic dogs) originated in North America 40 million years ago but initially comprised primarily small raccoon-like forms. Although dogs later grew into one of the most diverse carnivore groups, they became large and carnivorous only in the Oligocene and Miocene epochs, 20 million years into their history - why? As the smaller early dogs lived alongside potentially large carnivore competitors - bears, bear-dogs, false saber-toothed cats, and weasels and allies - the North American Oligo-Miocene presents an ideal system to investigate how competition may have shaped, even suppressed, the initial diversification of a group. Inferring competition in the fossil record is difficult and depends on reconstructing body size and diet from dental and skeletal remains. To do so, this project will use both linear measurements and dental complexity analysis, a new technique that quantifies tooth surfaces using geographic information systems measures. Dental complexity captures the texture of teeth adapted for different diets, ranging from herbivory to carnivory. Combined, these approaches allow the classification of extinct species into body size and dietary types. This can then be used to quantify the potential for competition between dogs and other carnivorous mammals throughout their early evolutionary history. Studying early dogs and their potential competitors will aid understanding of current carnivore communities at this time of accelerated global change.