Ontocetus is an extinct genus of walrus

Walrus

The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic...

, an aquatic

Aquatic

Aquatic means relating to water; living in or near water or taking place in waterAquatic may also refer to:* Aquatic animal, either vertebrate or invertebrate, which lives in water for most or all of its life...

 carnivoran of the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Odobenidae

Odobenidae

Odobenidae is a family of Pinnipeds. The only living species is walrus.In the past, however, the group was much more diverse, and includes more than ten fossil genera.- Taxonomy :All genera, except Odobenus, are extinct.*Prototaria...

, endemic to coastal regions of the southern North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 and the southeastern coastal regions of the U.S. during the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

-Pleistocene

Pleistocene

The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

. It lived from 13.6 mya—300,000 years ago, existing for approximately .

Taxonomy

Originally named Alachtherium by Du Bus (1867) (type Alachtherium cretsii.). It was It was assigned to Odobenidae

Odobenidae

Odobenidae is a family of Pinnipeds. The only living species is walrus.In the past, however, the group was much more diverse, and includes more than ten fossil genera.- Taxonomy :All genera, except Odobenus, are extinct.*Prototaria...

by Palmer (1904) and Kellogg (1922). Ontocetus was named by Joseph Leidy

Joseph Leidy

Joseph Leidy was an American paleontologist.Leidy was professor of anatomy at the University of Pennsylvania, and later was a professor of natural history at Swarthmore College. His book Extinct Fauna of Dakota and Nebraska contained many species not previously described and many previously...

 (1859). Its type is Ontocetus emmonsi. It was considered monophyletic by Uhen (2010). It was synonymized subjectively with Hoplocetus by Trouessart (1898); it was considered a nomen dubium

Nomen dubium

In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...

by Fordyce and de Muizon (2001). It was assigned to Sirenia

Sirenia

Sirenia is an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. Four species are living, in two families and genera. These are the dugong and manatees...

by Cope (1875); to Physeterinae by Hay (1902) and Simpson (1945); to Physeteridae by Gill (1871), Palmer (1904), Barnes (1977) and Carroll (1988); to Cetacea

Cetacea

The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...

by Sepkoski (2002); to Odobeninae by Kohno (2006); to Odobenini by Kohno and Ray (2008); and to Odobenidae by Ray (1975) and Uhen (2010).
Ontocetus oxymycterus was named by Kellogg (1925). Its type specimen is USNM 10923 and is a 3D body fossil. Its type locality is Santa Barbara Lighthouse, which is in a Serravallian marine dolomite in the Monterey Formation of California. It was recombined as Scaldicetus oxymycterus by Kohno and Ray (2008).