See you later... crocodile? The ecological diversity of the crocodylians and their relatives

Abstract

Can you tell the difference between a crocodile and an alligator? It is a tricky task for most people. Although they come in different sizes and have other slight differences, most modern crocodylians look pretty much the same to a non-specialist eye. However, the picture is very different when we consider the 200-million-year evolution of the crocodylian lineage. Many fossil species of Crocodyliformes, the group that includes crocodylians and their relatives, are completely different from the semi-aquatic forms we have today. These extinct crocodyliform species include fully sea-going forms with flippers, giant dinosaur-eating terrestrial predators, greyhound-like fast-running small omnivores, bizarre filter-feeders, and even plant-eaters with complex mammal-like dentitions. Accordingly, my PhD research project aims to investigate and understand which environmental and biological factors drove the evolution of this huge diversity, as well as its decline towards the low ecological diversity seen today. To do this I am collecting anatomical data and information on body size and mass from hundreds of fossil specimens worldwide. I will use this data to quantify changes in ecological diversity through time, and will compare the results with environmental (climate and geographical) data and major evolutionary changes (e.g. origins of major lineages).