What does the term crocodylian bring to mind? A big reptile with a chomping jaw?

Crocodylians are the 27 species of crocodiles, alligators, caimans and gharials that live all over Earth today, except for in Europe and Antarctica. There are some smaller species, but these top predators are usually big, at least 2 meters long. They also share a general shape and look – for instance, how easily can you tell an alligator and a crocodile apart?

The fossil record of crocodylians is much richer, though, with many different forms and body sizes and extraordinary ecological diversity.

Over their long evolutionary history of more than 200 million years, crocs experimented with different lifestyles, as well as various body lengths. But exactly which environmental factors might have influenced the body sizes of crocs throughout their evolution? And does the body size of crocs suggest something about past species’ extinction?

To investigate, my colleagues and I created a complete map of body sizes of crocs through time. Body size can reveal a lot about the biology of extinct animals. Our study was the first to apply some modern computational methods to understand body size evolution in crocs.