PhD: Phylogeny and biogeographic history of early Crocodylia

Representatives of Crocodylia, the group including modern-day alligators, caimans, crocodiles, and gharials, formed a major element of lowland ecosystems during the Paleogene and have an extensive fossil record accordingly. This makes them an excellent model clade for addressing a broad range of macroevolutionary questions such as the environmental drivers of biodiversity in deep time. Their evolutionary history during the Paleogene is of particular interest as diversity of crocodylians was considerably higher compared to modern days with usually several disparate species in a single ecosystem. During this time, intercontinental dispersals played a major role in diversification which was facilitated by the prevailing greenhouse conditions. The Paleogene evolutionary history of crocodylians remains largely uncertain because phylogenies including fossils are unstable due to limited sampling. The student will focus on the rich and often exquisitely preserved Laurasian Paleogene fossil record of Crocodylia. The aim is to improve phylogenetic resolution and divergence timing through increased sampling of Asian fossils, collecting of new material from the field, review of stratigraphy, CT-scanning, revision of key European and North American taxa, assessment of intraspecific variation and character correlation, and utilization of molecular data using various evolutionary models. This dataset will be then used to address the impact of environment, ecology, and biogeography on the rates of diversification and morphological evolution in Paleogene crocodylians.