''Trigonostylops'' is an extinct genus of South American

meridiungulata South American native ungulates, commonly abbreviated as SANUs, are extinct ungulate-like mammals of controversial affinities that were indigenous to South America prior to the Great American Biotic Interchange. They comprise five major groups co ...

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, cam ...

, from the

Late Paleocene The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...

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

(

Itaboraian The Itaboraian ( pt, Itaboraiense) age is a period within the Early Eocene geologic time (53.0–50.0 Mya (unit), Ma) epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes ...

Tinguirirican The Tinguirirican ( es, Tinguiririquense) age is a period of geologic time (36.0–29.0 Ma) within the Late Eocene and Early Oligocene epochs of the Paleogene, used more specifically within the SALMA classification in South America. It follows th ...

in the SALMA classification) of South America (

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

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

) and Antarctica (

Seymour Island Seymour Island or Marambio Island, is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is the closest part of Antarctica to South America. It lies within the section of the isla ...

). It is the only member of the family Trigonostylopidae.

Description

A complete

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

of the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, ''T. wortmani'', has been found, and it has been classified as an astrapothere based on its large lower incisors.

Phylogeny

Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

based in the

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

published by Vallejo Pareja ''et al''., 2015, showing the position of ''Trigonostylops'':Vallejo Pareja et al., 2015

Distribution

Fossils of ''Trigonostylops'' have been found in:''Trigonostylops''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org ;Paleocene * Las Flores Formation,

Goin et al., 2009 ;Eocene *

La Meseta Formation The La Meseta Formation is a sedimentary sequence deposited during the Eocene. The formation is found on Seymour Island, Antarctica. Description La Meseta Formation lies unconformably on the Cretaceous Lopez de Bertodano Formation. It is an app ...

, AntarcticaDzik & Gaździcki, 2001 * Casamayor,

Divisadero Largo __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 ...

, Koluel Kaike and

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- ...

Vera, 2012Cifelli, 29185, p.5 *

Pozo Formation Pozo may refer to: People * Alejandro Pozo (born 1999), Spanish footballer * Angelica Pozo, American clay artist * Arnulfo Pozo (born 1945), Ecuadorian cyclist * Arquimedez Pozo (born 1973), Dominican baseball player * Chano Pozo (1915–1948), C ...

Antoine et al., 2011

References

Bibliography

* * * * * * {{Taxonbar, from=Q1815379 Meridiungulata Paleocene mammals Eocene mammals Paleocene mammals of South America Eocene mammals of South America Tinguirirican Divisaderan Mustersan Casamayoran Riochican Itaboraian Paleogene Argentina Paleogene Peru Fossils of Argentina Fossils of Peru Paleogene animals of Antarctica Cenozoic mammals of Antarctica Fossils of Antarctica Fossil taxa described in 1897 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Sarmiento Formation