''Cetotherium'' ("whale beast") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

baleen whales 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 m ...

from the family

Cetotheriidae Cetotheriidae is a family of baleen whales (parvorder Mysticeti). The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by recovered the living ...

Taxonomy

The family Cetotheriidae and the genus ''Cetotherium'' (

sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...

) have been used as wastebaskets for all kinds of baleen whales, most notably by , Spassky (1954) and . Based on more recent phylogenetic studies and revisions of many 19th century genera, much smaller monophyletic Cetotheriidae and ''Cetotherium''

sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...

is limited to a single or only a few species. For example, included only ''C. rathkii'' and ''C. riabinini'' in the genus and only ten genera in the family. Cetotheriidae were thought to have gone extinct during the Pliocene until 2012, when it was hypothesized that the

pygmy right whale The pygmy right whale (''Caperea marginata'') is a species of baleen whale. It may be a member of the cetotheres, a family of baleen whales which until 2012 were thought to be extinct; ''C. marginata'' has otherwise been considered the monoty ...

was the sole surviving species of this family.

Formerly assigned to ''Cetotherium''

The following species were originally described as nominal species of ''Cetotherium'' but have been either reassigned to other genera or removed from ''Cetotherium'': * ''Cetotherium furlongi'' Kellogg, 1925, is known from a partial skull from the

Burdigalian The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma (million years ago). Preceded by the Aquitanian, the Burdigalian was the first and longest war ...

of the Vaqueros Formation in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

, but the holotype is lost. * ''Cetotherium gastaldii'' Strobel, 1875, known from the early Pliocene-age Sabbie d'Asti Formation of the

Piedmont it, Piemontese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...

region in Italy, is now the type species of the eschrichtiid genus '' Eschrichtioides''. * ''Cetotherium klinderi'' Brandt, 1871,Brandt, J. F. 1871. Bericht uber den Fortgang meiner Studien uber di Cetaceen, welche das grosse zur Tertiarzeit von Mitteleuropa bis Centralasien hinein ausgedehnte Meeresbechen bevolkerten. Bulletin de l'Académie Impériale de Saint-Pétersbourg 16: 563–566. is known from an isolated earbone from Miocene sediments in Chişinău,

Moldova Moldova ( , ; ), officially the Republic of Moldova ( ro, Republica Moldova), is a landlocked country in Eastern Europe. It is bordered by Romania to the west and Ukraine to the north, east, and south. The unrecognised state of Transnist ...

. Although fragmentary, it is not congeneric with the two species of ''Cetotherium''. * ''Cetotherium maicopicum'' Spasski, 1951, based on a specimen from the late

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

of the Russian

Caucasus The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia (country), Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range ...

, was reassigned to the genus '' Kurdalagonus'' from the same region in 2012, although Gol'din and Startsev (2016) have questioned this referral. * ''Cetotherium mayeri'' Brandt, 1871, known from a partial skeleton, has been reassigned to ''

Mithridatocetus ''Mithridatocetus'' is a genus of cetotheriid mysticete in the subfamily Cetotheriinae. Known specimens have been found in marine deposits in Crimea, Ukraine, and the Russian Caucasus.P. Goldin and D. Startsev. 2016. "A systematic review of c ...

''. ''Cetotherium incertum'' Brandt, 1873, known from a vertebra, and ''"Ziphius" priscus'' Eichwald, 1840 are ''nomina dubia'', while ''Cetotherium pusillum'' Nordmann, 1860 requires re-assessment.

Evolution

Cetotheres came into existence during the

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 ...

epoch. The cetotheres have been divided into two sub-groups. One group includes ''Cetotherium''. From evolutionary perspective, these whales share some characteristics of the

Balaenopteridae Rorquals () are the largest group of baleen whales, which comprise the family Balaenopteridae, containing ten extant species in three genera. They include the largest animal that has ever lived, the blue whale, which can reach , and the fin wha ...

and

Eschrichtiidae Eschrichtiidae or the gray whales is a family of baleen whale (Parvorder Mysticeti) with a single extant species, the gray whale (''Eschrichtius robustus''), as well as three described fossil genera: '' Archaeschrichtius'' and '' Eschrichtioides ...

Paleobiology

Fossil records have revealed a predator-prey relationship between large sharks (e.g. '' O. megalodon'') and Cetotheriids. The raptorial

toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species ...

, '' Livyatan melvillei'', may too have posed a threat to these whales. The skeleton of an ancient whale was unearthed by archeologists in

Crimea Crimea, crh, Къырым, Qırım, grc, Κιμμερία / Ταυρική, translit=Kimmería / Taurikḗ ( ) is a peninsula in Ukraine, on the northern coast of the Black Sea, that has been occupied by Russia since 2014. It has a p ...

in 2018. The whale disappeared 10 million years ago.

References

Notes

Sources

*Barry Cox, Colin Harrison, R.J.G. Savage, and Brian Gardiner. (1999): The Simon & Schuster Encyclopedia of Dinosaurs and Prehistoric Creatures: A Visual Who's Who of Prehistoric Life. Simon & Schuster. * * ** * ** * ** * * * ** {{Taxonbar, from=Q478604 Baleen whales Miocene cetaceans Neogene mammals of North America Prehistoric cetacean genera Fossil taxa described in 1843