Odobenidae

The walrus (Odobenus rosmarus; plural walrus or walruses) is a large pinniped marine mammal with discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. It is the only extant species in the family Odobenidae and genus Odobenus. This species is subdivided into two subspecies: the Atlantic walrus (O. r. rosmarus), which lives in the Atlantic Ocean, and the Pacific walrus (O. r. divergens), which lives in the Pacific Ocean.

Odobenidae is a family of pinnipeds, of which the only extant species is the walrus (Odobenus rosmarus). In the past, however, the group was much more diverse, and includes more than a dozen fossil genera.

Pontolis is an extinct genus of large walrus. It contained three species, P. magnus, P. barroni, and P. kohnoi. Like all pinnipeds, Pontolis was a heavily built amphibious carnivore. Pontolis lived along the Pacific coast of North America along what is now the western coasts of California and Oregon between 11.608 and 5.332 million years ago, during the Miocene and Pliocene.

thumb|left|Restoration of foraging Gomphotaria pugnax with Dusignathus in foreground

Valenictus is an extinct genus of Odobenidae from the Pliocene of California.

Ontocetus is an extinct genus of walrus, an aquatic carnivoran of the family Odobenidae, endemic to coastal regions of the southern North Sea and the southeastern coastal regions of the U.S. during the Miocene-Pleistocene. It lived from 13.6 mya—300,000 years ago, existing for approximately .

Pliopedia pacifica is an extinct species of walrus found in what is now Central Valley, California, United States, which lived during the late Miocene. It was an amphibious carnivore.

Neotherium mirum is an extinct species of basal walrus. It was smaller than living forms and it did not have long tusks. Males were larger than females.

Aivukus is an extinct genus of walrus from the Miocene.

Nanodobenus is an extinct genus of pinniped that lived approximately 15.97 to 7.246 mya during the Miocene in what is now Baja California Sur, Mexico. It belonged to the family Odobenidae, the only extant species of which is the walrus. thumb|A map of the area where Nanodobenus fossils were discovered

Pelagiarctos was a genus of walrus that lived during the Middle Miocene, approx. 13-15 mya. Its fossilised remains have been found in the Sharktooth Hill Bonebed, in Kern County, California. It was originally described as an Otariidae, though it is now usually considered to be a basal Odobenidae.

Archaeodobenus is an extinct genus of pinniped that lived during the Late Miocene of what is now Japan. It belonged to the Odobenidae family, which is today only represented by the walrus, but was much more diverse in the past, containing at least 16 genera.

Imagotaria is an extinct monotypic genus of walrus with the sole species Imagotaria downsi. Fossils of Imagotaria are known from the early late Miocene of California (c. 10-12 million years ago).