Raptor may have scavenged on tyrannosaur in Alberta badlands, study finds

EDMONTON · A new study points to a raptor dinosaur as the likely source of bite marks found on the jawbone of a young Albertosaurus. The fossil, discovered north of Drumheller, Alta., in 2022, suggests a smaller predator scavenged the larger tyrannosaur after its death. University of Alberta master's student Joshua Doyon led the research, which compared the spacing of the tooth marks to known dinosaurs from the Late Cretaceous period. The findings offer a rare glimpse into feeding interactions between carnivorous dinosaurs roughly 70 million years ago.

Doyon said the most probable scenario is that a dromaeosaurid, commonly called a raptor, fed on the Albertosaurus carcass. "At that time, something happened to this dinosaur. It died. And right after it died, or soon after, something bit it and was feasting on the meat," Doyon said. The alternative, less likely explanation is that a very young Albertosaurus, about two metres long, cannibalized the larger sub-adult. The eight-year-old Albertosaurus was estimated to be six metres long and weigh 530 kilograms.

The fossil was reported by a member of the public and prepared by the Royal Tyrrell Museum, where technicians first noted the unusual marks. Researchers found no signs of bone healing, indicating the bites occurred around the time of death. By measuring the spacing between the marks, Doyon's analysis ruled out most contemporary carnivores. The study is described as the first evidence of a raptor feeding or scavenging on a tyrannosaur.

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Philip Currie, a University of Alberta professor of dinosaur paleobiology and Doyon's supervisor, said such evidence is uncommon. "This is one of those rare occasions where we actually have information on a carnivore eating a carnivore," Currie said. "It's a pretty big deal." He noted Albertosaurus was a dominant apex predator, while the suspected raptor would have been closer in size to a German shepherd. The local raptor species, Atrociraptor, was about two metres long.

The discovery could help researchers better understand the prehistoric food web and interactions between species. Currie said examining such details on fossils can reveal more about dinosaur biology beyond simple identification. Doyon said he hopes the find encourages closer examination of small marks on future fossil discoveries. The Albertosaurus specimen, described as a close relative of Tyrannosaurus rex, lived in what is now Alberta between 73 and 67 million years ago.

With files from The Canadian Press, Global News and CBC News