Litopterna is an extinct order of South American native ungulates that lived from the Paleocene to the end of the Pleistocene-early Holocene around 63 million-12,000 years ago, and were also present in Antarctica during the Eocene. They represent the second most diverse group of South American ungulates after Notoungulata. It is divided into nine families, with Proterotheriidae and Macraucheniidae being the most diverse and last surviving families.
Cramauchenia is an extinct genus of litoptern South American ungulate. Cramauchenia was named by Florentino Ameghino. The name has no literal translation. Instead, it is an anagram of the name of a related genus Macrauchenia. This genus was initially discovered in the Sarmiento Formation in the Chubut Province, in Argentina, and later it was found in the Chichinales Formation in the Río Negro Province and the Cerro Bandera Formation in Neuquén, also in Argentina, in sediments assigned to the SALMA Colhuehuapian, as well as the Agua de la Piedra Formation in Mendoza, in sediments dated to the Deseadan. In 1981 Soria made C. insolita a junior synonym of C. normalis. A specimen of C. normalis was described in 2010 from Cabeza Blanca in the Sarmiento Formation, in sediments assigned to the Deseadan SALMA.
The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene. These periods are referred to as ages, stages, or intervals and were established using geographic place names where fossil materials where obtained.
The Santacrucian age is a period of geologic time within the Early Miocene epoch of the Neogene, used more specifically with SALMA classification in South America. It follows the Colhuehuapian and precedes the Friasian age.
The Chasicoan age is a period of geologic time from 10–9 Ma within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Mayoan and precedes the Huayquerian age.
The Huayquerian age is a period of geologic time within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification. It follows the Chasicoan and precedes the Montehermosan age.
Proterotheriidae is an extinct family of litoptern ungulates known from the Eocene-Late Pleistocene of South America. Members of the group were small-medium sized cursorial herbivores with brachydont teeth, with their toes showing progressive reduction, with later members of the group bearing weight on a single large toe similar to living horses.
Neolicaphrium is an extinct genus of ungulate mammal belonging to the extinct order Litopterna. This animal lived from the Late Pliocene (Chapadmalalan) to the Late Pleistocene (Lujanian) in southern South America, being the last survivor of the family Proterotheriidae.
The Cerro Azul Formation, also described as Epecuén Formation, is a geological formation of Late Miocene age in the Colorado Basin of the Buenos Aires and La Pampa Provinces in northeastern Argentina.
Cullinia is an extinct genus of litoptern, an order of South American native ungulates that included horse-like and camel-like animals such as Macrauchenia. It is only known from fragmentary remains. Cullinia levis is known from Chasicoan remains found in the Arroyo Chasicó Formation of Argentina, and remains from the Brazilian state of Acre and the Huayquerian Ituzaingó Formation have been assigned to Cullinia sp..
Proterotherium is an extinct genus of litoptern mammal of the family Proterotheriidae that lived during the Late Miocene of Argentina and Chile. Fossils of this genus have been found in the Ituzaingó Formation of Argentina, and the Galera Formation of Chile.
Deuterotherium is an extinct genus of South American native ungulates, which lived during the Deseadan age of the Oligocene in what is now Argentina. Its type species is Deuterotherium distichum. It was named by Florentino Ameghino in 1895. The holotype of Deuterotherium distichum is a calcaneum. It was formerly identified as a proterotheriid litoptern. In 1999, Shockey argued Deuterotherium was certainly not a litoptern and interpreted it as a notohippid notoungulate. In research by Soria posthumously published in 2001, Soria considered Deuterotherium a nomen dubium.
Polymorphis is an extinct genus of litopterns belonging to the family Macraucheniidae. It lived during the Middle Eocene of Argentina.
Uruguayodon is an extinct genus of proterotheriid from the middle Pleistocene of Uruguay. It is known from the type and only species U. alius, named by Corona and colleagues in 2019 for dentaries and a partial postcrania from the Raigón Formation. Uruguayodon represents one of the latest occurrences of Proterotheriidae, with only Neolicaphrium representing other remains from the Pleistocene to possibly Holocene.
Brachytherium is an extinct genus of proterotheriid mammal from the Late Miocene to Late Pliocene of Argentina. It is represented by the type and only species B. cuspidatum, a taxon named in 1883 by Ameghino for a partial mandible with teeth. Though it was considered a dubious taxon at times, Brachytherium was revised as valid by Schmidt in 2015, who also synonymized the species Proterotherium gradatum and Lophogonodon paranensis, expanding the material known, all of which is from the Ituzaingó Formation. Some material previously referred to Brachytherium has been given the new name Neobrachytherium.
Neobrachytherium is an extinct genus of proterotheriid mammal from the Late Miocene of Argentina and Uruguay. It is represented by multiple species, including the type N. intermedium, originally named in 1891 by Moreno and Mercerat as a species of Licaphrium, N. morenoi, originally named in 1914 by Rovereto as a species of Brachytherium, and N. ameghinoi and N. ullumense, named in 2001 by Soria, who reclassified all the species in the new genus Neobrachytherium. The various species are known from cranial and dental material from the Corral Quemado, Loma de las Tapias and Ituzaingó Formations. Neobrachytherium may be closely related to Thoatherium, Diadiaphorus and Thoatheriopsis.
Xesmodon is an extinct genus of mammal. It lived from the Middle to the Late Eocene, in what is today South America.
Tetramerorhinus is an extinct genus of proterotheriid litoptern that lived during the Early and Middle Miocene in what is now Argentina and Peru.
Anisolophus is an extinct genus of proterotheriid from the Early to Middle Miocene of Argentina. The genus was named by Burmeister in 1885 to accommodate the species Anchitherium australe, which they had named earlier in 1879. Soria then referred the species Licaphrium floweri and Anisolophus minisculus to the genus, making Licaphrium, named in 1887 by Florentino Ameghino, a junior synonym of the genus. Both A. australis and A. floweri are known from the Santacrucian age Santa Cruz Formation, while A. minisculus is known from the Collón Curá Formation.
Paramacrauchenia is an extinct genus of proterotheriid litopterns from the Early Miocene of what is now Argentina and Chile. Its fossils have been found in the Sarmiento and Santa Cruz Formations of Argentina and Chile.
