Raptor may have scavenged on tyrannosaur in Alberta, researchers say
The bite marks on an Albertosaurus jawbone suggest a smaller carnivorous dinosaur fed on the larger predator after it died.
EDMONTON — 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.
The discovery centres 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 roughly 70 million years ago.
"This is one of those rare occasions where we actually have information on a carnivore eating a carnivore," said Philip Currie, a University of Alberta professor of dinosaur paleobiology.
READ MORE: Researchers hunt for deadly amphibian fungus in Manitoba wetlands
READ MORE: Canadian scientists find natural hydrogen flowing underground
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.
"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.
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.
Researchers narrowed the possibilities to two potential culprits.
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.
Currie said evidence of one carnivorous dinosaur feeding on another is rare.
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.
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.
Currie said the discovery highlights how paleontologists can learn more about dinosaur biology by examining details on fossils, rather than focusing only on identifying and describing the animals.
Albertosaurus was an apex predator in its ecosystem, while the suspected raptor would have been much smaller, roughly comparable in size to a German shepherd, Currie said.
Doyon said the raptors that lived around Drumheller belonged to a group called dromaeosaurs. The local species, Atrociraptor, was about two metres long.
Doyon said he hopes paleontologists and members of the public who find dinosaur bones will pay closer attention to small tooth marks that may otherwise go unnoticed.
With files from The Canadian Press, Global News and CBC News