The Triassic Transition: Analyzing niche replacement between major clades of fossil vertebrates

三叠纪(约252-200 Ma)古生代与现代动物群之间的转换是地球历史上最重要的生物转变之一。在这一转变过程中的分类周转是众所周知的，但其背后的进化过程仍然不清楚。关于主要陆生脊椎动物群体的这种转变的进化动力学，有两种相互竞争的假说：竞争与生态机会主义。我将首次通过对二叠纪、三叠纪和侏罗纪陆生脊椎动物下巴形状(已知与食物生态位相关的一种)的几何形态分析，直接定量检验这些假说。这项研究的结果将对了解恐龙和哺乳动物的起源具有重要意义。他们还将更全面地阐明大规模灭绝后的更替动态，这是对当前人类介导的脊椎动物灭绝的长期影响进行建模的重要信息。

The shift between Paleozoic and modern faunas during the Triassic Period (c. 252-200 Ma) was one of the most important biological transitions in Earth history. Taxonomic turnover during this transition is well known, but the evolutionary processes underlying it remain obscure. There are two competing hypotheses of the evolutionary dynamics of this transition in major terrestrial vertebrate groups: competition vs. ecological opportunism. I will quantitatively test these hypotheses directly for the first time, using geometric morphometric analysis of lower jaw shape (a known correlate of dietary niche) in terrestrial vertebrates from the Permian, Triassic, and Jurassic periods. The results of this research will have important implications for understanding the origins of dinosaurs and mammals. They will also more generally elucidate the dynamics of replacement following mass extinctions, vital information for modelling the long-term effects of current human-mediated vertebrate extinctions.