76-Million-Year-Old Pterosaur Bone with Crocodilian Bite Found in Canada | Sci.News
Understanding food chains in ancient ecosystems is one of the goals of paleoecology. Direct evidence for these interactions is rare and includes fossils with stomach contents and bite/tooth marks. Paleontologists from the Royal Tyrrell Museum of Palaeontology, the University of Reading and the University of New England have documented a rare occurrence of a bite mark to the neck vertebra of a juvenile fossil specimen of a giant azhdarchid pterosaur from the Cretaceous of Alberta, Canada, around 76 million years ago. Based on the size and shape of the tooth mark, and comparison with modern animals, the authors suggest that a crocodylian bit the pterosaur, but they were unable to determine whether this was active predation or scavenging. Feeding traces on giant pterosaurs are rare, so this provides novel details on how they fit into this ancient ecosystem.
The fossilized neck bone of a juvenile of Cryodrakon boreas shows tell-tale signs (right part of the specimen in 2 and 8) of being bitten by a crocodile-like creature 76 million years ago. Image credit: Brown et al., doi: 10.1017/jpa.2024.12.
The 76-million-year-old neck vertebra was unearthed July 2023 in the Dinosaur Park Formation in Alberta, Canada.
The preserved (i.e., incomplete) length of the specimen is 5.8 cm; the estimated total length of the vertebra is 9.4 cm.
The specimen bears a circular 4-mm-wide puncture mark from a crocodilian tooth.
“Pterosaur bones are very delicate — so finding fossils where another animal has clearly taken a bite is exceptionally uncommon,” said Dr. Caleb Brown, a paleontologist at the Royal Tyrrell Museum of Palaeontology.
“This specimen being a juvenile makes it even more rare.”
The punctured vertebra belongs to a juvenile (estimated wingspan of 2 m) of Cryodrakon boreas, a species of giant azhdarchid pterosaur that lived during the Late Cretaceous epoch in what is now Canada.
Adults of this species would have been as tall as a giraffe with a wingspan in the region of 10 m.
“With an estimated wingspan equivalent to some of the largest azhdarchids, Cryodrakon and other large-bodied azhdarchids were probably substantial terrestrial foragers,” the paleontologists said
“Bite marks, embedded teeth, and stomach contents indicate that azhdarchid pterosaurs were fed upon by velociraptorine theropods and crocodylomorphs.”
Cryodrakon boreas. Image credit: David Maas.
In the study, they used micro-CT scans and comparisons with other pterosaur bones to confirm the puncture is not a result of damage during fossilization or excavation, but an actual crocodilian bite.
“Bite traces help to document species interactions from this period,” said Dr. Brian Pickles, a paleontologist at the University of Reading.
“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 study was published online today in the Journal of Paleontology.
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Caleb M. Brown et al. A juvenile pterosaur vertebra with putative crocodilian bite from the Campanian of Alberta, Canada. Journal of Paleontology, published online January 23, 2025; doi: 10.1017/jpa.2024.12
