Locally found fossils tell an incredible story of interaction between a prehistoric shark and whale.
In a recently published paper in the French paleontological journal “Carnets de Geologie,” Calvert Marine Museum paleontologists describe a 12- to 15-million-year-old Miocene baleen whale radius (one of the flipper bones) that was bitten repeatedly by a prehistoric shark.
The shark bites and head-thrashings were so forceful that both the upper and lower teeth in the jaws of the shark cut multiple gouges into the whale bone.
At least three successive bite-shake traces — made by multiple teeth — mark both the upper and lower sides of the whale radius.
These bite-shake traces consist of shallow, thin arching gouges that likely indicate scavenging rather than active predation. The most likely way the three sets of shark bite-shake traces would have been made would be by repeated biting as the shark repositioned the whale flipper in its mouth to remove flesh.
“This bone is very unusual because it preserves so much evidence of head-thrashing behavior of an extinct shark feeding on an extinct whale,” Calvert Marine Museum Curator of Paleontology Stephen Godfrey said in a news release.
When a whale dies, it inverts and floats at the surface of the water due to the buildup of abdominal gases from decomposition. Scavenging sharks usually feed at the water line, occasionally lifting their heads out of the water. The flippers of the whale lie at the water line and extend outward from the body, providing an easy target for scavengers.
From the similarity of the three bite traces on the dorsal side of the radius, scientists think they were made by the same teeth during successive bite-shake events. The shark would have clenched down on the flipper firmly and then shaken its head vigorously in an attempt to cut through the bone (unsuccessfully) or to simply remove flesh.
It is thought that the bites were made in order which would likely have resulted in the removal of some flesh covering the flipper. Following that, the shark might have re-bitten the bone at, shaken its head and successfully removed more flesh before proceeding to biting and head shaking.
There is no evidence of healing on the surface of the now-fossilized whale bone, which means that the whale — if it was alive at the time the shark bit it, which is doubtful — did not survive the encounter with the shark.
The well-preserved bone was found along Calvert Cliffs, one of the most fossiliferous regions on the east coast of the continental United States, by local fossil hound Douggie Douglass.
In addition to the innumerable body fossils, the Calvert Cliffs preserve trace fossils which reveal evidence of animal behavior, including burrows made by invertebrates, coprolites (fossilized poop) and fossilized bones with shark bite traces.
The Calvert Marine Museum will be exhibiting this fossil along with many others in its “Sharks! Sink Your Teeth In!” exhibit, which runs through December 2022.