''Ashorocetus'' is a monotypic genus of an extinct primitive

baleen whale Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their ...

of the family Aetiocetidae. It was named by , and contains one species, ''A. eguchii''. Fossils of this whale are found from the

Chattian The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Morawan formation, near

Ashoro is a town located in Tokachi Subprefecture, Hokkaido, Japan. As of September 2016, the town has an estimated population of 7,150 and a density of 5.1 persons per km2. The total area is 1,408.09 km2. It was the largest municipality in Jap ...

, of upper

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

() Hokkaido, Japan (, paleocoordinates ). ''Ashorocetus eguchii'' was described based on a partial skull and is named after the type locality and Kenichiro Eguchi of the Ashoro Museum of Paleontology.

Description

described four new aetiocetid species, of whom ''Ashorocetus eguchii'' was the most primitive. It has a neatly telescoped skull and is closely related to ''Chonecetus'', another primitive aetiocetid. Barnes et al. also described '' Morawanocetus yabukii'', a more derived species with a foreshortened braincase, intermediate between ''Chonecetus'' and '' Aetiocetus''; ''Aetiocetus tomitai'', the most primitive ''Aetiocetus'' discovered; and ''Aetiocetus polydentatus'', the most derived ''Aetiocetus'' with a highly telescoped cranium and both homodont and polydont dentition. Barnes et al. also proposed three subfamilies for Aetiocetidae (Chonecetinae, Morawanocetinae, and Aetiocetinae) to reflect this proposed evolution within the family. The placement of ''A. polydentatus'' in ''Aetiocetus'' has, however, been questioned, as has the monophyly (and therefore the proposed subfamilies) of Aetiocetidae.

Sister taxa

*'' Aetiocetus'' *'' Chonecetus'' *'' Morawanocetus'' *''

Willungacetus ''Willungacetus'' is an extinct genus of primitive baleen whale of the family Aetiocetidae known from the Oligocene of Australia (at Port Willunga, , paleocoordinates ). It is the oldest-known whale from Australia, and the only aetiocetid wh ...

References

Notes

Sources

* ** * ** * Extinct animals of Japan Oligocene mammals of Asia Aetiocetidae Prehistoric monotypic mammal genera Prehistoric cetacean genera Fossil taxa described in 1995 {{paleo-whale-stub