Several fossil teeth from the giant predatory shark Otodus megalodon show scratch marks that could only have been made by members of their own species, suggesting that the largest sharks of all time may have fought by sparring with their jaws.
Between 23 million and 3.6 million years ago, megalodon, which may have grown up to 24 metres long, swam the world’s oceans. Now, at the Calvert Marine Museum in Maryland and his colleagues have studied four teeth from fossil sites in North and South Carolina dating to about 12 million years ago.
Each one had parallel scratch marks characteristic of the gouges made by O. megalodon’s serrated teeth. “Meg-bitten teeth are exceedingly rare in the fossil record,” says Godfrey.
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One of the teeth was scratched perpendicular to its length. This damage couldn’t have been caused by a shark biting in such a way as to scratch its own teeth, which raises the possibility of combat between two sharks. Alternatively, the megalodon’s body may have been scavenged by another megalodon after it died.
It is possible that each tooth was marked in a different way, says at the University of Pisa in Italy, who wasn’t involved in the study. “Sharks that feed on carrion occasionally leave their teeth embedded in bitten items, where they may receive or record their own bites,” he says.
Nevertheless, researchers have uncovered other evidence that megalodons weren’t shy about biting predators around the mouth. have also been found with O. megalodon bite marks.
It is unclear whether the sperm whales or megalodons were alive or carrion when bitten, but both scenarios are possible, says Godfrey. “Extant sharks are known to engage in cannibalism and scavenging, and these meg-bitten teeth could have come about because of comparable encounters,” he says.
Acta Palaeontologica Polonica
