''Colpodon'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

, belonging to the order

Notoungulata Notoungulata is an extinct order of ungulates that inhabited South America from the early Paleocene to the end of the Pleistocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms re ...

. It lived during the Early

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, in what is today

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

and

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

, in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Description

This animal is almost exclusively known from cranial remains, and its general appearance is globally unknown. From a comparison with some of its better known relatives, like ''

Scarrittia ''Scarrittia'' is an extinct genus of hoofed mammal of the family Leontiniidae, native to South America during the Late Oligocene epoch (Deseadan in the SALMA classification). Description ''Scarrittia'' was about in body length, and resem ...

'' and ''

Huilatherium ''Huilatherium'' is an extinct genus of leontiniid, a group of hoofed mammals belonging to the order Notoungulata, that comprises other South American ungulate families that evolved in parallel with some mammals of the Northern hemisphere. The l ...

'', it can be supposed that ''Colpodon'' was a relatively heavy-shaped animal, with a stature comparable to that of a

sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...

. Its skull was rather short and tall, with a characteristic set of teeth, differing from most of its close relatives, the

Leontiniidae Leontiniidae is an extinct family comprising eighteen genera of notoungulate mammals known from the Middle Eocene (Mustersan) to Late Miocene (Huayquerian) of South America South America is a continent entirely in the Western Hemisphere ...

. The upper canines were completely absent, and the incisors were well-developed bu lacking labial girdles.

Classification

''Colpodon'' was one of the first notoungulates ever discovered. It was first described in 1885 by

Hermann Burmeister Karl Hermann Konrad Burmeister (also known as Carlos Germán Conrado Burmeister) (15 January 1807 – 2 May 1892) was a German Argentine zoologist, entomologist, herpetologist, botany, botanist, and coleopterologist. He served as a professor at ...

, who described the genus based on two upper and two lower molars found near the mouth of the

Chubut River The Chubut River (; ; ) is located in the Patagonia region of southern Argentina. Its name comes from the Tehuelche word , which means 'transparent'. The Argentine Chubut Province, through which the river flows, is named after it. Welsh settle ...

. Burmeister considered ''Colpodon'' as an intermediate form between ''

Nesodon ''Nesodon'' ("island tooth")Palmer (1904) p. 457. is a genus of Miocene mammal belonging to the extinct order Notoungulata which inhabited southern South America during the Late Oligocene to Miocene living from 29.0 to 16.3 Ma and existed for a ...

'' and ''

Homalodotherium ''Homalodotherium'' is an extinct genus of South American native ungulates in the order Notoungulata. Fossils of ''Homalodotherium'' have been found in the Middle Miocene ( Friasian in the SALMA classification) Santa Cruz Formation of Argentina ...

''. Subsequently, Burmeister described another species of ''Colpodon'', ''C. propinquus''. In the early 1900s,

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino; September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especial ...

described other species of ''Colpodon'', ''C. distinctus'' and ''C. plicatus'', and believed that this animal was a member of the family Leontiniidae. In the following years ''Colpodon'' was variously placed among Leontiniidae and

Notohippidae Notohippidae is a paraphyly, paraphyletic extinct Family (biology), family of Notoungulata, notoungulate mammals from South America. Notohippids are known from the Eocene and Oligocene Epoch (reference date), epochs.McKenna, Malcolm C., and Bell ...

due to its peculiar dentition with characters shared by both families ; ''Colpodon'' also had a symmetrical astragalus, like the Notohippidae. In 2012 another species of ''Colpodon'', ''C. antucoensis'', was described from

. This species is slightly more recent than the type species, and is differentiated from it by some dental characters and a narrower muzzle. Moreover, other fossil remains assigned to this genus have been found in the

Chichinales Formation The Chichinales Formation is a geological formation in Río Negro Province, Argentina which dates from the Late Oligocene to the Early Miocene, around 23 to 17.5 million years ago. It predominantly consists of pyroclastic deposits, which were dep ...

Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its cap ...

in Argentina. ''Colpodon'' is currently considered a derived member of the family Leontiniidae, a group of heavy-built notoungulates common during the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

. The 2012 study showed a close relationship between ''Colpodon'', ''

'' and ''

Taubatherium ''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. Description Fossils of this animal indicates that it had a fairly robust build, ...

'', two leontiniids from a tropical clade whose remains have been found in

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

and

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

References

*G. Burmeister. 1885. Examen critico de los mamiferos y reptiles fosiles denominados por D. Augusto Bravard y mencionados en su obra precedente. Annales del Museo Nacional de Buenos Aires 3:93-174 *F. Ameghino. 1904. Nuevas especies de mamíferos, cretáceos y terciarios de la República Argentina ew species of mammals, Cretaceous and Tertiarty, from the Argentine Republic Anales de la Sociedad Cientifica Argentina 56–58:1-142 {{Taxonbar, from=Q21078346 Toxodonts Miocene mammals of South America Neogene Argentina Fossils of Argentina Fossil taxa described in 1885 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Chichinales Formation Sarmiento Formation