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

点击翻译按钮获取中文摘要

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.