''Ethegotherium'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Notoungulate Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resemb ...

s, belonging to the suborder

Typotheria Typotheria is a suborder of the extinct mammalian order Notoungulata Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,0 ...

. It lived from the Lower to the Middle

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 recen ...

, and its fossilized remains were discovered in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. It might be a synonym of the genus ''

Prohegetotherium ''Prohegetotherium'' is an extinct genus of Hegetotheriidae, hegetotheriid Notoungulata, notoungulates from the Oligocene, Late Oligocene to Miocene, Early Miocene (Deseadan-Santacrucian in the South American land mammal age, SALMA classificatio ...

''.

Description

This was a small-sized animal, not exceeding the size of a

European rabbit The European rabbit (''Oryctolagus cuniculus'') or coney is a species of rabbit native to the Iberian Peninsula (including Spain, Portugal, and southwestern France), western France, and the northern Atlas Mountains in northwest Africa. It has ...

. ''Ethegotherium'' is only known from a skull and a mandible, and it is difficult to restore its complete appearance. From comparison with its relatives, it can be supposed that it was a small notoungulate with a short tail and long hind legs. It shared similarities with the slightly older ''

'', but differed from it in several ways, including its smaller size. The incisors and canines were directed forward, giving rise to a "false diastema" between them and the backward-directed first premolars. The upper canine had an arched crown, while the upper jugal teeth, with a high crown, were slightly imbricated, without any development of the parastyle area and with discontinuous enamel. Unlike ''Prohegetotherium'', the first upper premolar had no labial sulcus nor parastyle, while the second premolar had a deep lingual sulcus and the third premolar was quite large. For the lower molars, the trigonid was rounded and not cordiform like in ''Prohegetotherium''.

Classification

''Ethegotherium'' was a member of the

Hegetotheriidae Hegetotheriidae is an extinct family of notoungulate mammals known from the Oligocene through the Pliocene of South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a r ...

, a group of small-sized Notoungulates, similar in appearance to

lagomorph The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (λαγ� ...

s. The dental characteristics of this animal indicates affinities with ''Prohegetotherium'' and ''

Hegetotherium ''Hegetotherium'' is an extinct genus of mammals from the Early to Middle Miocene (Colhuehuapian-Colloncuran in the SALMA classification) of South America. Fossils of this genus have been found in the Cerro Bandera, Cerro Boleadoras, Chichina ...

'', within the Hegetotheriinae subfamily. The holotype of ''Ethegotherium carettei'' was first described in 1947 by José Luis Minoprio, based on fossils found in the

Mendoza Province Mendoza, officially Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the republic o ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, and firstly attributed to the genus ''Prohegetotherium'' as ''P. carettei''. Later, a study by

George Gaylord Simpson George Gaylord Simpson (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the Modern synthesis (20th century), modern ...

Bryan Patterson Bryan Patterson (born 10 March 1909 in London; died 1 December 1979 in Chicago) was an American paleontologist at the Field Museum of Natural History in Chicago. Life and career Bryan Patterson was the son of the soldier, engineer and author ...

and Minoprio himself identified several sufficiently distinctive characteristics for the establishment of a new genus, ''Ethegotherium'' (whose name is the

anagram An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once. For example, the word ''anagram'' itself can be rearranged into ''nag a ram'', also the word ...

of ''Hegetotherium''). However, there is still some debate on the exact generic attribution of the fossils. It was initially thought to have come from the

Divisadero Largo Formation __NOTOC__ Divisadero may refer to: Places Mexico * Divisadero, Chihuahua, a town on the Ferrocarril Chihuahua al Pacífico (Copper Canyon railroad) * Divisaderos, Sonora United States * Divisadero Street, in San Francisco * Divisadero Street, in ...

of the Late

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

, but further analyses of the rock matrix of the fossil tends to indicate that the holotype came from the Miocene Mariño Formation.Lopez, G. & Manassero, M. (2008): Revision of the stratigraphic provenance of Ethegotherium carettei (Notoungulata, Hegetotheriidae) by sedimentary petrography. – N. Jb. Geol. Paläont. Abh., 248: 1–9; Stuttgart.

References and Bibliography

*Minoprio, J. L. (1947): Fósiles de la Formación Divisadero Largo. – Anales Sociedad Científica Argentina, 144: 365–378. *Simpson, G. G., Minoprio, J. L. & Patterson, B. (1962): The mammalian fauna of the Divisadero Largo Formation. Mendoza, Argentina. – Bulletin of the Museum of Comparative Zoology, 127: 239–293. *Lopez, G. M. (2002): Redescripción de Ethegotherium carettei (Notoungulata, Hegetotheriidae) de la Formación Divisadero Largo de la provincia de Mendoza, Argentina. – Ameghiniana, 39 (3): 295–306. {{Taxonbar, from=Q110456206 Typotheres Miocene mammals of South America Neogene Argentina Fossils of Argentina Fossil taxa described in 1947 Prehistoric placental genera