Bite Marks on an Eighty-Million-Year-Old Cephalopod Fossil
Two distinct impact marks discovered on a fossilized cephalopod specimen housed at the Canadian Fossil Discovery Centre in Morden are offering new clues about the ancient marine food web of the Cretaceous period, ici.radio-canada.ca reported. The specimen itself was originally recovered in 1980 by Elizabeth Nicholls and her team, according to Melina Jobbins, a paleontologist and research associate at the centre. Years later, Jobbins and Kirstin Brink, a professor in the Department of Earth Sciences at the University of Manitoba, examined the drawers of the Morden museum and identified the impressions as potential evidence of prehistoric predation occurring roughly 80 million years ago. It is not a specimen recently extracted from the earth, but rather the result of decades of analyses. Cephalopods are scarce in the collections, which mostly contain vertebrates, small marine organisms, and a few birds. The cephalopod is an animal that could measure up to 1 meter in length.
Narrowing Down the Cretaceous Predators
A detailed inspection of the ancient mollusk allowed researchers to isolate two distinct trace fossils corresponding to predatory attacks. Jobbins stated that the team is ninety percent certain the first mark is a bite, matching either a mosasaur tooth or a fish tooth. The second imprint, located toward the rear of the creature, leaves room for debate, though researchers have put forward several hypotheses including a bite. Brink noted that the team has narrowed down the potential culprits to a mosasaur or a very large fish. At the time of the attack, the region between Morden and Miami was entirely submerged beneath the Western Interior Seaway, an ancient body of water that covered central North America and hosted formidable marine predators. This body of water covered central North America about one hundred kilometers southwest of the present-day city of Winnipeg. By finding clues about what these animals ate, researchers can interpret their diet and thus contribute to reconstructing the food web.
Ruling Out Prehistoric Sharks
Although the Cretaceous seaway teemed with massive prehistoric sharks, both scientists quickly dismissed the possibility that a shark inflicted the wounds. Brink confirmed that the team is practically certain the marks did not come from a shark, pointing out that shark teeth feature a distinctly different morphology and tend to leave entirely characteristic traces on bone when they bite. The shape of the perforations does not allow researchers to designate a single predator with certainty, because the teeth of a fish and those of a mosasaur from that period presented a very similar morphology. The original fossil remains on display in the galleries of the Canadian Fossil Discovery Centre, while the two female researchers hold teeth belonging to the presumed predators of the attack.
