Description
This genus is only known from incomplete remains, notably a well-preserved mandible and a fragmentary skull. Like other astrapotheres, Tetragonostylops may have had a strong elongated body, and a long, flat skull. The skull was 20 centimeters long, and the entire body was supposedly one meter long. Its mandible was strong, and endowed with an elongated cylindrical symphysis. The mandibular condyle was elevated, and the coronoid process was high, but lower than in its relative Trigonostylops . The shape of their molars was different, with Tetragonostylops having more squared molars (hence his name, Tetragon- meaning "four corners"), and had an infraorbital canal, which does not appear in Trigonostylops. The molars were brachyodont, like those of Trigonostylops, and the canines were strong and large. There was a large diastema between the canines and the premolars.
Xenungulata is an order of extinct and primitive South American hoofed mammals that lived from the Late Paleocene to Early Eocene. Fossils of the order are known from deposits in Brazil, Argentina, Peru, and Colombia. The best known member of this enigmatic order is the genus Carodnia, a tapir-like and -sized animal with a gait similar to living African elephants.
Trigonostylops is an extinct genus of South American meridiungulatan ungulate, from the Late Paleocene to Late Eocene of South America and Antarctica. It is the only member of the family Trigonostylopidae.
Pyrotherium is an extinct genus of South American ungulate, of the order Pyrotheria, that lived in what is now Argentina and Bolivia, during the Late Oligocene. It was named Pyrotherium because the first specimens were excavated from an ancient volcanic ash deposit. Fossils of the genus have been found in the Deseado and Sarmiento Formations of Argentina and the Salla Formation of Bolivia.
Carodnia is an extinct genus of South American ungulate known from the Early Eocene of Brazil, Argentina, and Peru. Carodnia is placed in the order Xenungulata together with Etayoa and Notoetayoa.
Astrapotheria is an extinct order of South American and Antarctic hoofed mammals that existed from the late Paleocene to the Middle Miocene, 59 to 11.8 million years ago. Astrapotheres were large, rhinoceros-like animals and have been called one of the most bizarre orders of mammals with an enigmatic evolutionary history.
Granastrapotherium is an extinct genus of ungulate mammals, described from remains found in rocks of the Honda Group in the Tatacoa Desert, in the Colombian departments of Huila and Tolima, at the Miocene fossil site La Venta. The only species formally recognized is Granastrapotherium snorki. Remains found in Bolivia and Peru, seem to belong to Granastrapotherium or a very similar animal.
Xenastrapotherium is an extinct genus of astrapothere, a type of hoofed herbivorous mammal, native to South America, which lived in the Middle to Late Miocene period, typically during the Laventan stage. It is a member of the family Astrapotheriidae in the subfamily Uruguaytheriinae, large astrapotheres, equipped with a trunk-like nose and protruding teeth, similar to the elephants, but their tusks were the canine teeth, not the incisors. Xenastrapotherium was a genus widely distributed in northern South America, in contrast to other species of astrapotheres which lived in the area of the Southern Cone of the continent. It differed from other astrapotheres by having two lower incisors on each side of the jaw and the tusks have a pronounced longitudinal curvature, although their general shape and size are probably very similar to Astrapotherium, whose weight would be 900 to 1,500 kilograms, comparable to the current black rhinoceros.
Uruguaytherium is an extinct genus of astrapotherid mammal from the Late Oligocene to Early Miocene of South America. It was named by the Argentinean paleontologist Lucas Kraglievich in 1928, from a fragmentary fossil found in the Fray Bentos Formation of the department of Río Negro in Uruguay, and the type species is U. beaulieui. The related genera Xenastrapotherium and Granastrapotherium, which make up Uruguaytheriinae with Uruguaytherium, are also from South America, although them colonizated the equatorial zone. The holotype specimen of Uruguaytherium is a partial mandible (the left mandibular ramus), with a preserved third molar, or M3.
Hilarcotherium is an extinct genus of astrapotheriid mammals that lived in South America during the Middle Miocene (Laventan). The type species is H. castanedaii, found in sediments of the La Victoria Formation, part of the Honda Group in the department of Tolima in Colombia. In 2018, Carrillo et al. described a partial skull and mandible of a second species H. miyou from the Castilletes Formation in the Cocinetas Basin of northern Colombia, and estimated the body weight of the animal at 6,465 kilograms (14,253 lb).
Astraponotus is an extinct genus of astrapotheriids. It lived during the Middle-Late Eocene and its fossil remains have been found in the Sarmiento Formation of Argentina, South America.
Ernestokokenia is an extinct genus of mammal, belonging to the Didolodontidae. It lived during the Early Eocene and the Middle Eocene, and its fossils were discovered in South America.
Lamegoia is an extinct genus of mammals, belonging to the family Didolodontidae. It contains a single species, Lamegoia conodonta, which lived during the Late Paleocene in what is now South America.
Eoastrapostylops is an extinct genus of astrapothere that lived during the Late Paleocene in what is now Argentina.
Shecenia is an extinct genus of mammal, probably belonging to the order Astrapotheria. It lived between the Late Paleocene and the Early Eocene, and its fossilized remains were found in South America.
Astrapothericulus is an extinct genus of mammals, belonging to the order Astrapotheria. It lived during the Lower Miocene in what is now South America.
Asmithwoodwardia is an extinct genus of mammals, from the order Litopterna. It lived during the Late Paleocene and the Early Eocene, and its fossilized remains were found in South America.
Protolipterna is an extinct genus of mammal, belonging to the order Litopterna. It lived during the Late Paleocene and the Early Eocene, in what is now South America.
Anisolambda is an extinct genus of litoptern. It lived from the Late Paleocene to the Middle Eocene in what is now Argentina.
Colbertia is an extinct genus of oldfieldthomasiid notoungulate. It lived from the Early to the Middle Eocene, and its fossilized remains were discovered in Argentina and Brazil.
Periptychus is an extinct genus of mammal belonging to the family Periptychidae. It lived from the Early to Late Paleocene and its fossil remains have been found in North America.
