| Eoastrapostylops | |
|---|---|
 | |
| Skull of Eoastrapostylops | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | † Astrapotheria |
| Family: | † Eoastrapostylopidae |
| Genus: | † Eoastrapostylops Soria & Powell 1981 |
| Type species | |
| Eoastrapostylops riolorense Soria & Powell, 1981 | |
| Species | |
| |
Eoastrapostylops is an extinct genus of astrapothere that lived during the Late Paleocene in what is now Argentina.
This animal was small in size; the skull was 9 centimeters long and the total length of the animal probably just exceeded half a meter. Eoastrapostylops possessed a short muzzle ; its canines were well developed but not yet derived into large fangs, as was the case in later South American ungulates such as Trigonostylops , and the nasal bones were not retracted, indicating the absence of the typical proboscis exhibited by later forms.
The dentition of Eoastrapostylops recalls that of its later relative, Trigonostylops. molars and premolars were low-crowned and lophoselenodont-shaped. The fourth premolar was molarized, while both the fourth upper premolar and the third upper molar were triangularly shaped and lacked an hypoconus.
Eoastrapostylops riolorense was first described in 1981, based on fossils found in the Rio Loro Formation, in the Tucuman Province of Argentina. The authors immediately identified the traits of a primitive astrapothere, and therefore established the family Eoastrapostylopidae.
More recent researches have brought to light notable similarities between the auditory regions of Eoastrapostylops and those of archaic "condylarths" and litopterns. Those researches would indicate that Eoastrapostylops was one of the most basal member of the South American ungulates, and differentiated before the separation between astrapotheres, pyrothere and notoungulates. [1]
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.
Protypotherium is an extinct genus of notoungulate mammals native to South America during the Oligocene and Miocene epochs. A number of closely related animals date back further, to the Eocene. Fossils of Protypotherium have been found in the Deseadan Fray Bentos Formation of Uruguay, Muyu Huasi and Nazareno Formations of Bolivia, Cura-Mallín and Río Frías Formations of Chile, and Santa Cruz, Salicas, Ituzaingó, Aisol, Cerro Azul, Cerro Bandera, Cerro Boleadoras, Chichinales, Sarmiento and Collón Curá Formations of Argentina.
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 and rhinoceros-like animals and have been called one of the most bizarre orders of mammals with an enigmatic evolutionary history.
Astrapotherium is an extinct genus of South American mammals that vaguely resembled a small elephant or large tapir. However, it was unrelated to elephants or tapirs, but was instead related to other extinct South American ungulates. Fossils have been dated from the Early to Middle Miocene. Fossil remains of the type species A. magnus have been found in the Santa Cruz Formation in Argentina. Other fossils have been found in the Deseado, Sarmiento, and Aisol Formations of Argentina and Chile.
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.
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.
The Río Loro Formation is a geological formation of the Sierras Pampeanas in Tucumán Province Argentina whose strata date back to the Late Paleocene of the Paleogene, or Riochican in the SALMA classification.
Tremacyllus is an extinct genus of hegetotheriids. It lived from the Late Miocene to the Late Pleistocene and its fossilized remains were discovered in 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.
Propyrotherium is an extinct genus of mammals, belonging to the order Pyrotheria. It lived during the Late Eocene, in what is now South America.
Tetragonostylops is an extinct genus of mammal, related to Astrapotheria. It lived during the Late Paleocene, and its fossils were discovered 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.
Polymorphis is an extinct genus of litopterns belonging to the family Macraucheniidae. It lived during the Middle Eocene of Argentina.
Notonychops is an extinct genus of mammal, belonging to the order Litopterna, that lived during the Middle to Late Paleocene in what is today South America.
Proectocion is an extinct genus of herbivorous mammal, belonging to the order Litopterna. It lived during the Early Eocene, in what is now South America.
Notopithecus is an extinct genus of Notoungulate, belonging to the suborder Typotheria. It lived from the Middle to the Late Eocene and its fossilized remains were discovered in South America.
The Sarmiento Formation, 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-Eocene to the early Miocene. It predominantly consists of pyroclastic deposits, which were deposited in a semi-arid environment. It is divided up into a number of members. The diverse fauna of the Sarmiento Formation, including a variety of birds, crocodilians, turtles and snakes, also includes many mammals such as South American native ungulates as well as armadillos, and caviomorph rodents.
