A fossilised cervical vertebra from a pterosaur preserves a bite mark from a crocodilian. The neck bone was discovered during an international field course in the famous Dinosaur Provincial Park Formation (Alberta, Canada), that took place in July 2023. The course was led by Dr Brian Pickles from the University of Reading. The fossil bone preserves a four-millimetre-wide puncture mark from a crocodilian tooth. The punctured vertebra probably represents a bone from a juvenile Cryodrakon boreas.
The juvenile Cryodrakon boreas neck bone (bottom right) with an adult neck bone (top). Picture credit: University of Reading.
Picture credit: University of Reading
The researchers estimate that this animal had a wingspan of around two metres. However, much larger pterosaur bones from the Dinosaur Park Formation suggest that a fully-grown Cryodrakon could have rivalled Quetzalcoatlus in size. Indeed, when azhdarchid pterosaur bones were first discovered in this formation, the material was tentatively assigned to Quetzalcoatlus spp.
To read Everything Dinosaur’s blog post from 2019 about the discovery of Cryodrakon boreas: The First Pterosaur Unique to Canada.
A Juvenile Cryodrakon boreas
The study was undertaken by researchers from the Royal Tyrrell Museum of Palaeontology (Alberta), the University of Reading (UK) and the University of New England (Australia). The paper has been published today. The circular nature of the bite mark and other aspects of its morphology indicate that it was made by a crocodilian tooth. It is not known whether this is evidence of predation or whether the crocodilian scavenged a pterosaur carcase. However, it is remarkable evidence of predator/prey dynamics dating from the Late Cretaceous.
Lead author of the paper, Dr Caleb Brown (Royal Tyrrell Museum of Palaeontology), commented:
“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.”
Research team members working at the quarry where the juvenile Cryodrakon boreas cervical vertebra was found. Picture credit: University of Reading.
Picture credit: University of Reading
Fossils from this strata date from the Campanian faunal stage of the Late Cretaceous. This young pterosaur lived approximately seventy-six million years ago.
Comparing Pterosaur Bones and Using Micro-CT Scans
The scientists compared the single vertebra with other pterosaur bones to confirm that the puncture did indeed represent pathology. Evidence of an actual bite into the bone. Micro-CT scans were employed to permit a much more detailed analysis of the puncture wound.
Co-author Dr Brian Pickles (University of Reading) explained:
“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.”
This is the first documented evidence from North America of ancient crocodilians opportunistically feeding on pterosaurs. Azhdarchid bones with possible crocodilian bites have previously been recorded in Romania.
A researcher carefully brushes away debris from a fossil bone at a quarry located in the Dinosaur Provincial Park Formation. Picture credit: University of Reading.
Picture credit: University of Reading
Everything Dinosaur acknowledges the assistance of a media release from the University of Reading in the compilation of this article.
The scientific paper: “A juvenile pterosaur vertebra with putative crocodilian bite from the Campanian of Alberta, Canada” by Caleb M. Brown, Phil R. Bell, Holly Owers and Brian J. Pickles published in the Journal of Palaeontology.
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