Paleontologists working near Drumheller, Alberta, have identified bite marks left by a small raptor on the fossilized bones of a large carnivorous dinosaur, the first known evidence that a diminutive predator fed on one of the ecosystem's apex predators roughly 75 million years ago.
The marks, described in research reported by Phys.org, were found on bones excavated from the Drumheller area, a stretch of badlands in southern Alberta that has produced some of the richest Late Cretaceous fossil deposits in the world. The bite traces are small and closely spaced, matching the serrated teeth of a raptor far smaller than the animal whose skeleton they were found on.
The discovery leaves two possible explanations, and paleontologists have not ruled out either: the small raptor scavenged the carcass of an already-dead apex predator, or it was a juvenile of a large predatory species that fed on the adult. Distinguishing between the two scenarios matters because it changes how researchers reconstruct the food web of the Late Cretaceous, when the Drumheller region was a warm, seasonally wet floodplain crossed by river channels.
Drumheller sits within the Horseshoe Canyon and Dinosaur Park formations, sedimentary rock layers laid down between about 76 million and 74 million years ago. The area has yielded specimens of Albertosaurus, Daspletosaurus, and Gorgosaurus — tyrannosaurids that sat at or near the top of the local food chain. Raptors in the same deposits, including Saurornitholestes and Dromaeosaurus, were typically 2 to 3 meters long and weighed far less than the tyrannosaurids they shared the with.
Feeding traces like these are rare in the fossil record because they require an unusual chain of events: a carcass that was scavenged, bones that were not destroyed in the process, and sediment that buried the remains quickly enough to preserve them. Paleontologists use the spacing, shape, and depth of tooth marks to estimate the size of the animal that made them, which is how the Drumheller traces were linked to a small raptor rather than a larger predator.
Scavenging was likely common among Cretaceous carnivores, but direct physical evidence of it is sparse. The Drumheller marks add a documented case to a short list of known theropod feeding traces, and they raise the possibility that small raptors routinely exploited kills made by much larger animals — a feeding strategy that would have let them draw calories from prey they could not have brought down themselves.
The bones and the tooth traces on them are now part of the fossil collections tied to the Drumheller region, where the Royal Tyrrell Museum holds much of the material recovered from the surrounding badlands.
