Emily Chan
Walruses are known for their long tusks and fuzzy, mustached faces, but a recently discovered species looks a little different from the image of walruses that we’re used to.
The new species of ancient walrus is now extinct and once lived in the North Sea. Its discovery shows how walruses evolved to become expert suction feeders.
The ancient walrus belongs to the genus Ontocetus and was discovered by a team of paleontologists led by Dr. Mathieu Boisville from the University of Tsukuba in Japan.
The find has captured the attention of researchers because of its surprising similarities to the modern walrus (Odobenus rosmarus).
The new species has been named Ontocetus posti. Its fossils were uncovered in Norwich, United Kingdom, and Antwerp, Belgium, from the Lower Pleistocene deposits in the North Atlantic. Initially, it was believed the remains belonged to another species, Ontocetus emmonsi.
However, a more thorough analysis revealed a distinct combination of features that confirmed it as a new species.
The features consisted of four post-canine teeth, a larger lower canine, and a fused and shorted mandibular symphysis. The fused jaw was similar to that of modern walruses, allowing them to suck mollusks out of a shell. This shows that O. posti was well-adapted to suction feeding.
It took millions of years for walruses to develop the ability to suction feed. The process began with the loss of teeth in ancestors. The remaining teeth flattened out to feed on shells more easily. Now, the only teeth that remain are the upper canines, which developed into the iconic tusks we know today.
The Ontocetus genus originated from the North Pacific Ocean and spread to the Atlantic during the Mio-Pliocene transition. A crucial oceanic passage known as the Central American Seaway likely facilitated their migration.
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