A new analysis of fossil evidence of the prehistoric beast shows it was more of a fish-eater than an apex predator with a bone-crushing bite.
Traces of the middle Miocene walrus, named Pelagiarctos thomasi, were first found in the 1980s in the Sharktooth Hill bone bed of California. A chunk of a robust jawbone and sharp pointed teeth, which resembled those of the bone-cracking hyena, led researchers to believe the walrus ripped apart birds and other marine mammals in addition to the fish that modern walruses eat today.
But a more complete lower jaw and teeth from the long-gone species were recently discovered in the Topanga Canyon Formation near Los Angeles. Researchers say the shape of the teeth from this new specimen suggest the walrus was unlikely adapted to regularly feed on large prey. Instead, they think it was a generalist predator, feasting on fish, invertebrates and the occasional warm-blooded snack.
"When we examined the new specimen and the original fossils, we found that the teeth really weren't that sharp at all — in fact, the teeth looked like scaled-up versions of the teeth of a much smaller sea lion," researcher Robert Boessenecker, a geology doctoral student at the University of Otago in New Zealand, told the PLOS ONE Community Blog.
Using a model to estimate body size based on the size of the jaw, Boessenecker and Morgan Churchill of the University of Wyoming found that Pelagiarctos was quite large — about 770 pounds (350 kilograms), or similar in size to some modern male sea lions. But they noted that a big body alone likely wouldn't indicate that the species was a dominant predator. That's because both large and small modern species in the pinniped family — which includes seals, sea lions and walruses — are dietary generalists that tend to eat mostly fish.
Boessenecker added that the new findings give a clearer picture of the modern walrus' evolutionary past.
Read more at Discovery News
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