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

竞争是肉食哺乳动物在生态、结构和功能上差异的一个常见解释。在很长的时间尺度上，它也可以解释现在的食肉动物群落是如何聚集的。狗（狼、胡狼、狐狸、土狼、家犬）起源于4000万年前的北美，但最初主要是由像浣熊一样的小动物组成。虽然狗后来发展成为最多样化的食肉动物群体之一，但它们只是在渐新世和中新世才变成大型食肉动物，这是它们历史上的2000万年——为什么？由于早期较小的狗与潜在的大型食肉动物竞争对手——熊、熊狗、假剑齿虎、黄鼠狼及其盟友——生活在一起，北美渐近-中新世提供了一个理想的系统，可以用来研究竞争是如何塑造甚至抑制一个群体最初的多样化的。从化石记录中推断竞争是困难的，这取决于从牙齿和骨骼遗骸中重建体型和饮食。为此，该项目将使用线性测量和牙齿复杂性分析，这是一种使用地理信息系统测量来量化牙齿表面的新技术。牙齿的复杂性捕获了适应不同饮食的牙齿的纹理，从食草动物到食肉动物。综合起来，这些方法可以将灭绝物种分为体型和饮食类型。这可以用来量化狗和其他食肉哺乳动物在早期进化史上的竞争潜力。研究早期的狗和它们潜在的竞争对手将有助于了解在这个加速的全球变化时期当前的食肉动物群落。

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.