PhD: Neuroanatomical insights into the evolution and biogeography of alligatoroid crocodylians

Alligators and caimans are remnants of a diverse crocodylian radiation known as alligatoroids. These first appeared in the Late Cretaceous of North America, expanding into Asia, Europe, and South America. Our understanding of their biogeographic history is obscured by uncertainty in reconstructions of their evolutionary relationships. It is difficult to reconcile their distribution without allowing for transoceanic dispersal, yet living species are salt intolerant. One aspect of alligatoroid anatomy has yet to be incorporated into phylogenetic analyses, but has the potential to shed new light. The PhD student will reconstruct the neuroanatomy of several alligatoroid fossil species based on CT scan data. They will use this to understand the evolution of the brain and inner ear of extinct alligatoroids, with implications for their ecology. One of these early alligatoroids represents a new, undescribed species, and thus the external anatomy of its skeleton will also be described. The PhD student will also formulate new phylogenetic characters based on neuroanatomical data. These will be incorporated into an existing crocodylian data matrix, with the aim to increase resolution in alligatoroid interrelationships, including resolving the evolutionary relationships of the new species. This new evolutionary tree will then be used as the basis for a biogeographic analysis, including testing for the role of transoceanic dispersal in the distribution of alligatoroid diversity.