Some forensic dentistry on prehistoric teeth has shed new light on the evolution of walruses, seals and sea lions and cast doubt on theories of an ancient "killer walrus" that ate other marine mammals, according to a New Zealand-led study out Tuesday.

The multidisciplinary team of researchers, led by Otago University, analyzed the internal structure of tooth enamel in a fossil walrus from California, Pelagiarctos thomasi, and in teeth of modern pinnipeds, the New Zealand fur seal and sea lion.

It was the first time the enamel ultrastructure of fur seals and sea lions, as well as the extinct walrus Pelagiarctos, was studied using scanning electron microscopy, study co-author Dr Carolina Loch said in a statement from the university.

"Pelagiarctos was originally thought to have been a 'killer walrus' that fed on large prey such as other marine mammals, but we found it has an enamel layer reasonably similar to that of modern New Zealand fur seals and sea lions, which are fish and squid eaters," Loch said.

The enamel structure meant Pelagiarctos was unlikely to be up to crunching through large bones without cracking its teeth, she said.

The study showed how using techniques and methods commonly employed in dentistry could answer questions with broader implications in the biology and evolution of animal species.

"Features and structures of the enamel layer have long been associated with differences in diet and tooth usage among animals, and can also help in the understanding the relationships among fossil and living species," said Loch.

"Teeth are not only the focus of modern dentistry, but also valuable tools for biologists, archaeologists and palaeontologists."

Pelagiarctos is thought to have lived about 14.5 million years ago. Endit

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