Thalattosuchia: neurosensory development during a land-to-water evolutionary transition

Dr Julia Schwab successfully defended her thesis in 2022 after working as a PhD student at the University of Edinburgh and co-supervised by National Museums Scotland.

Last updated: 30 May 2023

About the research

This Leverhulme Trust-funded PhD project focused on a group of long-snouted marine reptiles called thalattosuchians. These extinct animals were distant relatives of living crocodiles, and they evolved from an ancestor that was fully adapted to life on land. What makes them particularly interesting from an evolutionary perspective is that they show varying degrees of adaptation to life in the water. One lineage, the teleosauroids, were notably more crocodile-like in appearance, while the metriorhynchoids possessed a shark-like tail and had paddle-like limbs. This variation in adaptation is similar in many respects to what we see today in seals and dolphins.

Thalattosuchian marine adaptations related to the body are easy to see, but land animals that have re-adapted to life in water also have to undergo changes to their senses. For instance, an animal that lives surrounded by air has different balance requirements to one that lives in denser and more supportive water. Little was known about how thalattosuchian senses differed depending on their degree of adaptation to life in the sea, but using micro X-ray CT techniques, this research uncovered how sensory structures within the skulls of these crocodylians varied. Results have been published in Proceedings of the National Academy of Science and The Journal of Vertebrate Paleontology.

Lead image: A fossil skull of the thalattosuchian Metriorhynchus (NMS G.1901.67.15-16) held in the collections of National Museums Scotland