Oceans today are home to a variety of seals, ranging from leopard seals darting through Antarctic surfs in pursuit of a penguin to endangered Hawaiian monk seals lounging on sunlit shores.

But how did seals first take the evolutionary dive into the oceans more than 30 million years ago? Paleontologists know that seals’ ancient ancestors lived and walked on land. But what helped transform them into marine mammals is a tale riddled with holes.

Recently, a pair of researchers studying prehistoric seal fossils and remains of modern species, discovered a new piece of the story. They reported last month in the Journal of Vertebrate Paleontology that contemporary seals attack and bite their prey using much the same technique that their ancestors did millions of years ago.

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Morgan Churchill, a paleontologist at the University of Wisconsin, Oshkosh who was not involved in the work, called this study of seals, “the first comprehensive analysis that’s looked at the skulls and mandibles of living species that also incorporates fossils.”