''Hydrodamalis'' is a genus of extinct

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

sirenia The Sirenia (), commonly referred to as sea cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct famili ...

marine mammal Marine mammals are mammals that rely on marine ecosystems for their existence. They include animals such as cetaceans, pinnipeds, sirenians, sea otters and polar bears. They are an informal group, unified only by their reliance on marine enviro ...

s. It included the

Steller's sea cow Steller's sea cow (''Hydrodamalis gigas'') is an extinction, extinct sirenian described by Georg Wilhelm Steller in 1741. At that time, it was found only around the Commander Islands in the Bering Sea between Alaska and Russia; its range exte ...

(''Hydrodamalis gigas''), the Cuesta sea cow (''Hydrodamalis cuestae''), and the Takikawa sea cow (''Hydrodamalis spissa''). The fossil genus '' Dusisiren'' is regarded as the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

of ''Hydrodamalis'': together, the two genera form the

dugong The dugong (; ''Dugong dugon'') is a marine mammal. It is one of four living species of the order Sirenia, which also includes three species of manatees. It is the only living representative of the once-diverse family Dugongidae; its closest ...

subfamily Hydrodamalinae. They were the largest member of the order Sirenia, whose only

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

members are the

(''Dugong dugon'') and the

manatee Manatees (, family (biology), family Trichechidae, genus ''Trichechus'') are large, fully aquatic, mostly herbivory, herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing t ...

s (''Trichechus'' spp.). They reached up to in length, making the Steller's sea cow among the largest mammals other than

whale Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea ...

s to have existed in the

Holocene epoch The Holocene () is the current geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Qu ...

. Steller's sea cow was first described by

Georg Wilhelm Steller Georg Wilhelm Steller (10 March 1709 – 14 November 1746) was a German-born naturalist and explorer who contributed to the fields of biology, zoology, and ethnography. He participated in the Great Northern Expedition (1733–1743) and his ob ...

, Cuesta by Daryl Domning, and Takikawa by Hitoshi Furusawa. The Steller's sea cow was the only member of the genus to survive into modern times, and, although had formerly been abundant throughout the North Pacific, by the mid 1700s, its range had been limited to a single, isolated population surrounding the uninhabited

Commander Islands The Commander Islands, Komandorski Islands, or Komandorskie Islands (, ''Komandorskiye ostrova'') are a series of islands in the Russian Far East, a part of the Aleutian Islands, located about east of the Kamchatka Peninsula in the Bering Sea. ...

. It was hunted for its meat, skin, and fat by fur traders, and was also hunted by aboriginals of the North Pacific coast, leading to its and the genus' extinction 27 years after discovery. The Cuesta sea cow along with the Takikawa sea cow were probably extinct at the end of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Ice Ages An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and Gre ...

and the subsequent recession of seagrasses—their main food source. Cladogram on the relations of the hydrodamalines based on a 2004 study by Hitoshi Furuwasha

References

{{Authority control Hydrodamalinae Mammal genera Taxa named by Anders Jahan Retzius Holocene extinctions