Tooth marks on Albertosaurus jaw point to a small raptor feeding on a tyrannosaur

Tooth marks on the jaw of an immature Albertosaurus found near Drumheller, Alberta, are most consistent with a small raptor feeding on a tyrannosaur, according to a study published online on 7 October 2026 in the Journal of Paleontology. Its authors call the fossil the first documented evidence of a dromaeosaurid feeding or scavenging on a tyrannosaurid, adding a feeding interaction to the picture of Alberta's Late Cretaceous ecosystem.

The finding rests on marks left in bone, rather than a preserved feeding animal. The researchers identify dromaeosaurids as the likeliest makers of those marks, but they cannot identify an individual dinosaur. Nor do the marks show what killed the Albertosaurus or whether the animal that fed on it had hunted it.

How researchers traced the marks on the Albertosaurus jaw

The specimen includes associated cranial material from the Horseshoe Canyon Formation. The study describes it as the smallest associated Albertosaurus skull discovered to date. Histology of an associated limb bone indicates that the animal was at least eight years old when it died, giving the researchers an age estimate alongside the evidence preserved in its jaw.

According to University of Alberta reporting, a member of the public found and reported scattered skull fragments near Drumheller in 2022. The Royal Tyrrell Museum collected and prepared the specimen. Museum technicians spotted what they suspected were tooth marks and sent the fragments to the University of Alberta for further analysis.

The absence of healing matters because it places the damage around the time of death or afterward, according to the researchers. It supports an interpretation involving feeding or scavenging, but cannot establish the sequence of the Albertosaurus's death. Doyon told the University of Alberta that the cause of death is unknown.

Why a smaller predator is the leading explanation

Albertosaurus was an apex predator in what is now Alberta during the Late Cretaceous, roughly 73 million to 67 million years ago, according to the University of Alberta account. The proposed feeding animal was from a smaller carnivorous group. Philip Currie, a University of Alberta paleontologist who supervised Doyon and coauthored the study, described the striking aspect of the finding as a small dinosaur feeding on a much larger tyrannosaur.

The University of Alberta account also sets out a less likely alternative: a young Albertosaurus may have made the marks while feeding on a larger member of its own species. Doyon based that possibility on the distance between the marks. The account estimates such a young animal at about two metres long, compared with roughly six metres and 530 kilograms for the subadult whose bones were marked.

That alternative would imply cannibalism, but the researchers' preferred explanation is dromaeosaurid feeding. Both interpretations concern a feeding trace on the jaw; neither establishes which particular animal left it. The fossil also does not distinguish a predator consuming an animal it killed from a scavenger feeding after another cause of death.

What the fossil adds to the dinosaur food web

The study says the specimen adds evidence about dromaeosaurid diet and interactions among carnivorous dinosaurs. Its authors suggest that young tyrannosaurids and dromaeosaurs may have participated in reciprocal predation or scavenging. That is a proposed wider relationship, while this specimen records one inferred feeding interaction at or after the Albertosaurus's death.

The same fossil also contributes information about the skull of a young Albertosaurus, the authors say. Its age estimate and small associated skull give researchers material to examine alongside the bite traces. What happened before the marks were made remains outside the fossil's reach: the animal's cause of death, the identity of the feeder and any hunting event are unresolved.