Description
This animal was roughly the size of a Virginia opossum, reaching approximately 50 centimeters in length excluding its tail. Its weight has been estimated to have been around 2 to 3 kilograms.
Colbertia had a relatively elongated skull, with low-crowned (brachydont) molars ; the cusps of the molars were joined to form ridge-like structures called lophs, and are therefore considered lophodont. The paracone and the metacone had notable folds. The ankle bones of Colbertia indicates that it was a plantigrade, an ancestral condition within Notoungulata. The bone morphology at the base of the skull was very similar to other basal Notoungulates, although the petrous bone had distinct characteristics also found in similar but slightly more recent notoungulates, such as Dolichostylodon .
Classification
The genus Colbertia was first described in 1952 by Carlos de Paula Couto, as a new genus for a species of notoungulate described two years earlier and attributed to the genus Oldfieldthomasia as O. magellanica. The type species of the genus is Colbertia magellanica, from the Early Eocene Itaboraí Formation of Brazil. Fossils attributed to other species, C. lumbrerense and C. falui, have been discovered in Argentina in slightly younger deposits, from the Middle Eocene.
Colbertia is a basal member of the suborder Typotheria, a group of notoungulates sharing similarities with hyraxes and rodents. Colbertia was a basal member of this clade, within the family Oldfieldthomasiidae, which may be paraphyletic. Colbertia may have been close to the most basal typothere, who subsequently derived and diversified considerably to occupy a variety of ecological niches.
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.
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.
Mesotheriidae is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging.
Mixotoxodon is an extinct genus of notoungulate of the family Toxodontidae inhabiting South America, Central America and parts of southern North America during the Pleistocene epoch, from 1,800,000—12,000 years ago.
Tetragonostylops is an extinct genus of mammal, related to Astrapotheria. It lived during the Late Paleocene, and its fossils were discovered in South America.
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.
Ethegotherium is an extinct genus of Notoungulates, belonging to the suborder Typotheria. It lived from the Lower to the Middle Miocene, and its fossilized remains were discovered in South America. It might be a synonym of the genus Prohegetotherium.
Rhyphodon is an extinct genus of notoungulate, who lived from the Middle to the Late Eocene in what is today South America.
Martinmiguelia is an extinct genus of Notoungulate, belonging to the family Leontiniidae. It lived during the Middle Eocene, and its fossil remains were found in South America.
Taubatherium is an extinct genus of mammal, belonging to the order Notoungulata. It lived during the Late Oligocene, in what is today Brazil, in South America.
Plesiotypotherium is an extinct genus of Notoungulate, belonging to the suborder Typotheria. It lived from the Middle to the Late Miocene, and its fossilized remains were discovered in South America.
Archaeopithecus is an extinct genus of Notoungulate, belonging to the suborder Typotheria. It lived during the Middle Eocene, in what is today Argentina.
Teratopithecus is an extinct genus of archaeopithecid notoungulate that lived during the Middle Eocene of what is now Argentina. Fossils of this genus have been found in the Sarmiento Formation of Argentina.
Dolichostylodon is an extinct species of mammal, belonging to the order Notoungulata. It lived during the Middle Eocene, and its fossilized remains were discovered in South America.
Oldfieldthomasia is an extinct genus of Notoungulate, probably related to the suborder Typotheria. It lived during the Middle Eocene, in what is today South America.
Ultrapithecus is an extinct genus of oldfieldthomasiid notoungulate that lived during the Middle Eocene of what is now Argentina.
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.
Rosendo is an extinct genus of notohippid notoungulates that lived during the Early Oligocene in what is now Argentina and Chile. Fossils of this genus have been found in the Sarmiento Formation and the Abanico Formations of Argentina and Chile.
