Trigonostylops

Trigonostylops; Temporal range: Late Paleocene-Late Eocene; (Itaboraian-Tinguirirican); ~58.7–33.9 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Skull restoration of Trigonostylops
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Superorder:	†Meridiungulata
Order:	†Astrapotheria
Family:	†Trigonostylopidae
Genus:	†Trigonostylops; Ameghino 1897
Type species
	Trigonostylops wortmani; Ameghino 1897
Species
	T. gegenbauri Roth 1899; T. wortmani Ameghino 1897;

Trigonostylops is an extinct genus of South American meridiungulatan ungulate, from the Late Paleocene to Late Eocene (Itaboraian to Tinguirirican in the SALMA classification) of South America (Argentina and Peru) and Antarctica (Seymour Island). It is the only member of the family Trigonostylopidae.

Description

A complete skull of the type species, T. wortmani, has been found, and it has been classified as an astrapothere based on its large lower tusks. In comparison with the later Astrapotherium magnum, it is estimated to have been around 1.50 metres (4.9 ft) long.^[1] Teeth, primarily molars, have been found and assigned to other species.

Phylogeny

Cladogram based in the phylogenetic analysis published by Vallejo Pareja et al., 2015, showing the position of Trigonostylops:^[2]

Trigonostylops

Scaglia

	Astrapotherium

	Astrapothericulus

Uruguaytheriinae

Uruguaytherium

	Hilarcotherium

	Xenastrapotherium

Granastrapotherium

Distribution

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Locations of Trigonostylops fossils

Pozo Formation

Sarmiento Formation

Las Flores Formation
Not show: La Meseta Formation in Seymour Island, Antarctica

Fossils of Trigonostylops have been found in:^[3]

Paleocene

Las Flores Formation, Argentina^[4]

Eocene

La Meseta Formation, Antarctica^[5]
Casamayor, Divisadero Largo, Koluel Kaike and Sarmiento Formations, Argentina^[6]^[7]
Pozo Formation, Peru^[8]

References

^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 249. ISBN 978-1-84028-152-1.
^ Vallejo Pareja et al., 2015
^ Trigonostylops at Fossilworks.org
^ Goin et al., 2009
^ Dzik & Gaździcki, 2001
^ Vera, 2012
^ Cifelli, 29185, p.5
^ Antoine et al., 2011

Bibliography

[EoDP-1] Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 249. ISBN 978-1-84028-152-1.

[Vallejo-Pareja-2] Vallejo Pareja et al., 2015

[FWTrigonostylops-3] Trigonostylops at Fossilworks.org

[Goin2009-4] Goin et al., 2009

[Dzik2001-5] Dzik & Gaździcki, 2001

[Vera2012-6] Vera, 2012

[Cifelli1985_p5-7] Cifelli, 29185, p.5

[Antoine2011-8] Antoine et al., 2011

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