A (relatively) tiny set of teeth marks has cooked up a couple different theories about the Late Cretaceous dinosaur food chain. A new study by University of Alberta master’s student Joshua Doyon has uncovered evidence that dromaeosaurids, the group of small dinosaurs commonly called raptors, may have scavenged on the sizable apex predator Albertosaurus. Albertosaurus are related to Tyrannosaurus rex and roamed what is now Alberta from about 73 to 67 million years ago. According to the Royal Alberta Museum, the species was a large, powerful hunter that could reach up to nine metres long and weigh three tons. “This turns everything on its head, because you’re dealing with a very small dinosaur eating a very big, mean, nasty dinosaur like a tyrannosaur,” says Philip Currie, the university’s lead paleontologist and Doyon’s supervisor. The collection of skull fragments used in the study belong to an adolescent, estimated to be about eight years old, six metres long and about 530 kilograms. They were found by a member of the public in 2022 and given to the Royal Tyrrell Museum to process before being passed onto Doyon and the University of Alberta. “The specimen became really exciting as it was being prepared,” Doyon said. “Preparers and the researchers at the Tyrrell museum made that discovery of those tooth marks preserved on the lower jaw of the specimen, so that really pushed it to be a priority research.” Doyon studied the marks meticulously and found no sign of bone healing, suggesting the adolescent predator likely died of unknown causes and not a Jurassic Park raptor pack take-down. “The placement of the tooth marks is in a really awkward spot to be attacking it when the dinosaur was alive. They’re on the lower jaw, and some are on the inside of the lower jaw,” he explained. And it might not have been a raptor at all; while a more unlikely hypothesis, analysis of the size and spacing of the tooth marks suggest the diner might have been a family relation. “If it is a young Albertosaurus, this would be an event of cannibalism by a baby, about two metres long,” Currie said. “Finding meat eaters is number one rare. Finding meat eaters that ate meat eaters is even rarer, and it has been reported before that we have evidence of cannibalism even in some tyrannosaurs, but in all cases these are rare, and they don’t happen very often.” Currie said. The study was published in the Journal of Paleontology and offers another piece of insight into the complex food web in Alberta’s dinosaur past. “It’s also a really small Albertosaurus, and we don’t find very many of these younger and smaller individuals of this group of dinosaurs,” Doyon said. “So it can be helpful for understanding how they change as they grow up.” With files from CTV News Edmonton’s Nicole Weisberg
