Researchers from the University of Alberta have made an astonishing finding revealing that a raptor dinosaur might have fed on a considerably larger tyrannosaur.

The team discovered bite impressions on the jawbone of an Albertosaurus, a close relative of Tyrannosaurus rex, which is often referred to as its “teenage cousin.” This dinosaur inhabited Alberta approximately 70 million years ago.

The fossil in question belonged to an eight-year-old Albertosaurus, a sub-adult that had not yet reached its full size. The bite marks led researchers to consider two highly contrasting theories regarding the circumstances surrounding the dinosaur’s death near Drumheller, Alta., located around 130 kilometers northeast of Calgary.

The prevailing theory posits that a raptor— a smaller, bipedal, carnivorous dinosaur— consumed the larger Albertosaurus post-mortem, following its death from unknown causes.

Philip Currie, a professor of dinosaur paleobiology at the University of Alberta, remarked, “This is one of those rare instances where we actually have evidence of a carnivore preying on another carnivore.”

Currie emphasized the significance of the discovery, noting that the Albertosaurus was one of the leading predators of its era.

This finding could shed new light on the interactions among carnivorous dinosaurs and the intricacies of the ancient food chain.

Joshua Doyon, a master’s student in paleontology at the U of A, spearheaded the investigation into the bite marks.

By analyzing the spacing between the marks and comparing them with the teeth of other carnivorous dinosaurs from the same period, the researchers concluded that a raptor was the most plausible explanation.

The alternative theory suggests that the Albertosaurus was cannibalized by a significantly younger individual of its own species, one less than two years old and approximately two meters in length.

Discovery prompts research initiative

A member of the public discovered the fossil in 2022 while canoeing and exploring the badlands north of Drumheller. The find was reported to the Royal Tyrrell Museum, which collected the specimen and prepared it by carefully removing the surrounding rock from the bone.

As museum staff reassembled the fossil, they observed the tooth marks, which led to Doyon’s research project in 2023.

A closer view of the fossils that Doyan used in his research. (Scott Neufeld/CBC)

Doyon expressed his interest in exploring dinosaur behavior and interspecies interactions when he approached museum researchers regarding potential projects.

The specimen provided a unique opportunity to examine a feeding interaction that occurred tens of millions of years ago.

Currie pointed out that this discovery illustrates how paleontologists can gain deeper insights into dinosaur biology by analyzing details found on fossils, rather than solely focusing on identification and description.

Features such as the tooth marks may aid researchers in understanding which animals fed on others and how various species interacted within ancient ecosystems.

The Albertosaurus was an apex predator in its habitat, while the suspected raptor would have been notably smaller—comparable in size to a German shepherd, according to Currie.

This finding is particularly important as it presents rare evidence of one carnivorous dinosaur consuming another, rather than preying on herbivorous animals.

The term “raptor” often evokes images of the dinosaurs seen in the Jurassic Park films; however, the species found in Alberta were smaller than their cinematic portrayals.

Doyon noted that the raptors that existed around Drumheller belonged to a group known as dromaeosaurs. The local species, Atrociraptor, measured about two meters long, significantly smaller than the dinosaurs depicted in the films.

Doyon hopes that both paleontologists and the public will pay closer attention to small tooth marks on dinosaur bones that might otherwise be overlooked.