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

meridiungulata South American native ungulates, commonly abbreviated as SANUs, are extinct ungulate-like mammals that were indigenous to South America from the Paleocene (from at least 63 million years ago) until the end of the Late Pleistocene (~12,000 years a ...

ungulate Ungulates ( ) are members of the diverse clade Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

, 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 Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

(

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

Tinguirirican The Tinguirirican () age is a period of geologic time (36.0–29.0 Mya (unit), Ma) within the Eocene, Late Eocene and Oligocene, Early Oligocene epochs of the Paleogene, used more specifically within the South American land mammal age, SALMA classi ...

in the SALMA classification) of South America (

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

and

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

) 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 isl ...

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

Description

A complete

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

of the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

, ''T. wortmani'', has been found, and it has been classified as an

astrapothere Astrapotheria is an extinct Order (biology), order of South American and Antarctic ungulate, hoofed mammals that existed from the late Paleocene to the Middle Miocene, ."The uruguaytheriine Astrapotheriidae from the rich middle Miocene Honda Grou ...

based on its large lower incisors.

Phylogeny

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

based in the

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

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 was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org ;Paleocene * Las Flores Formation,

Goin et al., 2009 ;Eocene *

La Meseta Formation The La Meseta Formation is a sedimentary sequence deposited during much of the Paleogene on Seymour Island off the coast of the Antarctic Peninsula. It is noted for its fossils, which include both marine organisms and the only terrestrial vertebr ...

, AntarcticaDzik & Gaździcki, 2001 * Casamayor, Divisadero Largo, Koluel Kaike and

Sarmiento Formation The Sarmiento Formation (Spanish language, 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 y ...

Vera, 2012Cifelli, 29185, p.5 * Pozo Formation,

Antoine et al., 2011

References

Bibliography

* * * * * * {{Taxonbar, from=Q1815379 Astrapotheria Paleocene 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 Eocene 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