A walrus relative from 10-9.5 million years ago was unearthed in Hokkaido, a region in Northern Japan. The animal, whose species was dubbed Archaeodobenus akamatsui after Dr. Morio Akamatsu, a curator emeritus of the Hokkaido museum, is estimated to have been 2.8-3 metres (about 10 feet) long and weighed 390-473 kgs (850-1050 lbs).
The most obvious feature of Archaeodobenus is its lack of tusks, a defining characteristic of living walruses. In fact the specimen’s upper canines were described as “moderate-sized” and measured only 8.6 cm (3.4 inches) long.
The modern-day walrus tusks that we have all come to know, may actually be a relatively new adaptation. Walrus ancestors may have actually resembled other pinnipeds, aquatic mammals with front and rear flippers, such as seals and sea-lions. The fossil record of the family Odobenidae, the family containing living walruses and their closest ancestors, shows a gradual change from sea-lion looking animals to the striking, long toothed walruses still alive today.