New research led by Dr. Caleb Brown, Curator of Dinosaur Systematics & Evolution at the Royal Tyrrell Museum, reveals a bite mark found in a fossil neck vertebra of a juvenile pterosaur from the Cretaceous of Alberta.
Pterosaurs were flying reptiles that lived from the Late Triassic (~220 million years ago) until the end of the Cretaceous Period (66 million years ago). Although pterosaurs had a nearly global distribution, pterosaur fossils are rare in many areas, including Alberta. The bones are incredibly thin and delicate, which means they do not fossilize easily.
The dinosaurs that lived in the Cretaceous of Alberta are well known, but only one species of pterosaur has been described. Cryodrakon boreas, named in 2019, belongs to the family Azhdarchidae. The species is one of the largest pterosaurs known, with a wingspan of up to 10 m. Despite its size, its fossilized bones are rare. While the newly discovered fossil is from this giant species, it is a juvenile specimen, with an estimated wingspan of only 2 m.
The specimen was discovered during excavation of a bonebed as part of an international palaeontology field school. University of Reading student Patrick Neuberger found the specimen at Alberta’s Dinosaur Provincial Park near the end of the field school’s 2023 season. The discovery of the bone itself was exciting due to the relative scarcity of pterosaur fossils. Once the specimen was catalogued at the Museum, a bite mark in the neck vertebra was identified, adding another layer of importance to the fossil. The specimen is now on display in the Museum’s “Fossils in Focus” exhibit, where visitors can view the bitemark in greater detail.
Given the limited record of bite marks on azhdarchid fossils, the field school team decided the specimen was worthy of a description. The Royal Tyrrell Museum’s Dr. Caleb Brown was joined by professors Dr. Phil Bell (University of New England) and Dr. Brian Pickles (University of Reading), as well as University of Reading student Holly Owers.
Dinosaur Provincial Park looked vastly different 76 million years ago. Cryodrakon boreas would have lived alongside both avian and non-avian dinosaurs, crocodiles, mammals, turtles, and other animals along a lush coastal plain. For a young pterosaur, there would have been multiple predators. The researchers had a question: could the type of animal that bit this young pterosaur be confidently identified?
Based on the size of the tooth mark and its round shape, the research team suggests the animal that bit the pterosaur was most likely a crocodylian. Crocodiles, both extinct and alive today, have been known to prey on flying creatures like birds, bats, and insects. However, it is possible that another carnivore could have caused the bite mark. Champsosaurus (an extinct crocodile-like reptile) and Eodelphis (a mammal) are other possible candidates.
The bite mark does not show signs of healing, indicating this was not a failed predation attempt. It is unclear whether the bite mark was the result of a successful predation event, or was caused during post-death scavenging. If the bite mark does represent active predation, the pterosaur might have been killed near the water surface while drinking or hunting for aquatic prey.
While large pterosaurs like Cryodrakon boreas were likely more terrestrial than other pterosaurs, their feeding strategy might still have relied on aquatic prey, putting them at risk from aquatic predators such as crocodiles. As this fossil is one of a few examples showing feeding interactions involving giant pterosaurs, it represents a chance to learn more about how animals interacted during the Cretaceous of Alberta.
Citation: Brown, C. M., Bell, P.R., Owers, H., Pickles, B.J. A juvenile pterosaur vertebra with putative crocodilian bite from the Campanian of Alberta, Canada. Journal of Paleontology. https://doi.org/10.1017/jpa.2024.12