Evolution The most widely accepted theory about the origins of the walrus is that it shares a caniform (dog-like carnivoran) ancestor with true seals and ear seals that is most closely related to the modern bear. The first walruses were smaller than their modern counterparts, but reached larger sizes before evolving into true walruses and double-tusked walruses. As they evolved, they had tooth simplification, developed tusks, and acquired a combination of terrestrial and aquatic locomotion. They also developed a squirt and suction feeding mechanism.

These developments occurred over a time range of 15-26 million years ago.