Researchers at the University of Alberta say they have discovered what could be the first evidence of a small raptor feeding on a much larger tyrannosaur — offering a glimpse into the feeding habits of dinosaurs millions of years ago.
The discovery centers on unusual bite marks found on the jawbone of an Albertosaurus — an apex predator related to Tyrannosaurus rex that lived in what is now Alberta during the Late Cretaceous period.
A study by U of A paleontology master’s student Joshua Doyon found the most likely explanation is that an eight-year-old Albertosaurus died of unknown causes and was fed on shortly afterward by a dromaeosaurid, or raptor.
The study describes the marks as the first evidence of a raptor feeding or scavenging on a tyrannosaur.
“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 told Global News on Friday.
Doyon said he began studying the specimen as an undergraduate in 2023, comparing the spacing between the bite marks with the spacing between the teeth of carnivorous dinosaurs that lived alongside Albertosaurus.
“We figure that out by measuring the spacing between each tooth mark on our fossil and comparing it to the spacing between the teeth of other carnivorous dinosaurs that coexisted with our Albertosaurus,” he said.
University of Alberta researchers say bite marks on an Albertosaurus found near Drumheller in the Alberta badlands could be the first evidence of a small raptor feeding on a tyrannosaur.
Joshua Doyon via University of Alberta
Researchers narrowed the possibilities to two potential culprits.
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Doyon said the more likely explanation is a raptor. The other, less likely possibility is a young Albertosaurus, which would mean the dinosaur cannibalized another member of its species.
“If it is a young Albertosaurus, this would be an event of cannibalism by a baby, about two metres long, eating a larger sub-adult,” Doyon said.
The larger Albertosaurus is estimated to have been about six metres long and weighed roughly 530 kilograms.
Philip Currie, a University of Alberta professor of dinosaur paleobiology and Doyon’s supervisor, said evidence of one carnivorous dinosaur feeding on another is rare.
“This is one of those rare occasions where we actually have information on carnivore eating a carnivore,” Currie said.
The Albertosaurus specimen, consisting of scattered skull fragments, was found north of Drumheller in Alberta’s badlands and reported by a member of the public in 2022.
It was collected and prepared by the Royal Tyrrell Museum, where technicians discovered what they suspected were tooth marks. The specimen was then forwarded to the University of Alberta for further analysis.
Researchers found no signs of healing around the marks, suggesting they were made around the time the Albertosaurus died or shortly afterward and were the result of feeding or scavenging.
University of Alberta researchers say bite marks on an Albertosaurus could be the first evidence of a small raptor feeding on a tyrannosaur.
Joshua Doyon via University of Alberta
Albertosaurus, whose name means “Alberta lizard,” was an apex predator that lived in what is now Alberta, roughly 73 to 67 million years ago.
Currie said examining details such as the marks found on the specimen can help researchers learn more about dinosaur biology, while Doyon said the discovery could provide a better understanding of feeding interactions in the prehistoric ecosystem.
“That might lead us to a better understanding of the interactions and who was eating who in that ecosystem,” Doyon said.
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