Rare pterosaur fossil reveals crocodilian bite 76m years ago

The juvenile pterosaur vertebra, discovered in Dinosaur Provincial Park, Alberta, bears a circular four-millimetre-wide puncture mark from a crocodilian tooth. Researchers from the Royal Tyrrell Museum of Palaeontology (Canada), the University of Reading (UK) and the University of New England (Australia) say this rare evidence provides insight into predator-prey dynamics in the region during the Cretaceous Period.

The discovery was made during an international field course that took place in July 2023, led by Dr Brian Pickles from the University of Reading.

Dr Caleb Brown from the Royal Tyrrell Museum of Palaeontology is the lead author of the paper. He said: "Pterosaur bones are very delicate -- so finding fossils where another animal has clearly taken a bite is exceptionally uncommon. This specimen being a juvenile makes it even more rare."

Dinosaur Provincial Park has produced some of the most important dinosaur fossil discoveries ever made.

The punctured vertebra belongs to a young Azhdarchid pterosaur (Cryodrakon boreas), with an estimated wingspan of two metres. Adults of this species would have been as tall as a giraffe with a wingspan in the region of 10m.

The researchers used micro-CT scans and comparisons with other pterosaur bones to confirm the puncture is not a result of damage during fossilisation or excavation, but an actual bite.

Dr Brian Pickles from the University of Reading and co-author of the paper said: "Bite traces help to document species interactions from this period. We can't say if the pterosaur was alive or dead when it was bitten but the specimen shows that crocodilians occasionally preyed on, or scavenged, juvenile pterosaurs in prehistoric Alberta over 70 million years ago."

The paper also shows that this new bone documents the first evidence in North America of ancient crocodilians opportunistically feeding on these giant prehistoric flying reptiles. Other examples of Azhdarchid bones with possible crocodilian bites have previously been found in Romania.