Miocene pinnipeds

Puijila darwini is an extinct species of stem-pinniped (seal) which lived during the Miocene about 21 to 24 million years ago. About a metre (3 feet) long, the animal had only minimal physical adaptations for swimming. Unlike modern pinnipeds, it did not have flippers and its shape was otter-like, albeit more specialized; its skull and teeth are the features that most clearly indicate that it is a seal.

Enaliarctos is an extinct genus of pinnipedimorph, and may represent the ancestor to all pinnipeds. The five species in the genus Enaliarctos have been recovered from late Oligocene and early Miocene (ca. 28-17 million years ago) strata of California and Oregon.

Potamotherium ('river beast') an extinct genus of caniform carnivoran from the Miocene epoch of France and Germany. It has historically been assigned to the family Mustelidae (otters, weasels, etc.), but more recent studies suggest that it represents a primitive relative of pinnipeds (seals, sea lions, etc.)

Acrophoca longirostris, also known as the swan-necked seal, is an extinct genus of Late Miocene pinniped. It was thought to have been the ancestor of the modern leopard seal; however, it is now thought to be a species of monk seal.

Allodesmus is an extinct genus of pinniped from the middle to late Miocene of California and Japan that belongs to the extinct pinniped family Desmatophocidae.

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.

Thalassoleon ("sea lion", from Greek: thalassa, the sea; and leon, lion) is an extinct genus of large fur seal. Thalassoleon inhabited the Northern Pacific Ocean in latest Miocene and early Pliocene. Fossils of T. mexicanus are known from Baja California and southern California. T. macnallyae is known from central California, and T. inouei (which may be a synonym of T. macnallyae) is known from Japan. Thalassoleon could be the ancestor of the modern northern fur seal. alt=Artist's Reconstruction of the extinct otariid Thalassoleon mexicanus|thumb|Artist's Reconstruction of Thalassoleon mexican

Desmatophoca is an extinct genus of early pinniped that lived during the Miocene, and is named from the Greek "phoca", meaning seal. A taxon of the family Desmatophocidae, it shares some morphological similarities with modern true seals. Two species are recognized: Desmatophoca oregonensis and Desmatophoca brachycephala. Little information exists regarding Desmatophoca, due to the small number of fossil samples obtained and identified.

Semantoridae is an extinct family of stem-pinnipeds with fossils found in France, Kazakhstan, and Canada, dating back to various points in time in the Miocene epoch. Based on their overall anatomy semantorids were not marine specialists, as their elongated bodies, a long tail and robust limbs suggest they were freshwater animals not unlike otters. Indeed, at least some taxa such as Semantor and Potamotherium were initially classified as mustelids closely related to otters.

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

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.

Aivukus is an extinct genus of walrus from the Miocene.

Monotherium is an extinct genus of phocid belonging to the subfamily Monachinae. It is known from fossils found in the middle to late Miocene of Belgium.

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.

Leptophoca is an extinct genus of earless seals from the North Atlantic realm.

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).

Piscophoca is an extinct genus of pinniped. The genus was named after the fossiliferous Pisco Formation in Peru, where the holotype was found. Other fossils of the genus were found in the Bahía Inglesa Formation of the Caldera Basin in Chile.

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.

Callophoca is an extinct genus of earless seals from the late Miocene to early Pliocene of Belgium and the US Eastern Seaboard.

Hadrokirus is an extinct genus of true seal (Phocidae) that lived on the coast of Peru and North Carolina about 6 million years ago. The type species, H. martini, was found in the Pisco Formation, together with other marine animals such as crustaceans, sharks, coastal birds, whales and aquatic sloths. The distinguishing feature of the seal was its teeth: they were extremely robust, hence the name (, "stout" in Greek; , tooth in Quechua). It is assumed that Hadrokirus martini was durophagous; its diet probably comprised crustaceans, small bivalves and other shelled animals, similar to that of t

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.

Platyphoca is an extinct genus of earless seals from Neogene marine deposits in the North Sea basin.