In a resource-scarce ancient Colorado hungry dinosaurs would go to extreme lengths for food, even if that meant eating one of their own, a new study has found.
Researchers from the University of Tennessee, Knoxville, discovered that a substantial amount of fossils from the Mygatt-Moore Quarry, which date back to the late Jurassic Period around 150 million years ago, bear bite marks from carnivorous theropods. These types of marks are typically rare as the carnivores usually targeted softer tissues, but in this quarry, nearly 29 percent of the 2,368 bones examined had theropod tooth indentations.
Reporting in PLOS ONE, the authors suspect, from the shape and nature of these markings, that the predominant theropod culprit is likely the large predator Allosaurus. The most abundant theropod in the quarry, its serrated teeth are consistent with the bulk of the bites, although its competitor Ceratosaurus may also be responsible.
The fact that these meat-eating animals ate other dinosaurs isn’t surprising, but what is of interest is the types of dinos they dug their teeth into. Whilst primarily the quarry fossils showed that the predators munched on herbivores, 17 percent of the bites were in fact on other theropod bones. Of these marks, around half were on less nutritious body parts.
All the evidence points towards a stressed ecosystem that forced theropods to scavenge through the decomposed remains of previous kills. This scarcity of food may also have prompted the carnivorous dinosaurs to turn on each other, which would explain the theropod-on-theropod bite marks found by researchers. If so, this would provide rare evidence for dinosaur cannibalism, and would be the first known instance of this behavior in Allosaurus.
“Big theropods like Allosaurus probably weren't particularly picky eaters, especially if their environments were already strapped for resources,” Dr Stephanie Drumheller, lead author from the University of Tennessee, said in a statement. “Scavenging and even cannibalism were definitely on the table.”
But Allosaurus is not the only dinosaur accused of cannibalism. “Very deep grooves” previously found on Tyrannosaurus rex bones from the Lance Formation, Wyoming, suggests that one of their own gnawed away on its dead body.