''Notopithecus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of Notoungulate, belonging to the suborder

Typotheria Typotheria is a suborder of the extinct mammalian order Notoungulata and includes five families: Archaeopithecidae, Campanorcidae, Interatheriidae, Mesotheriidae, and Oldfieldthomasiidae. CifelliCifelli, Richard L. 1993. The phylogeny of the nat ...

. It lived from the Middle to the Late Eocene and its fossilized remains were discovered in South America.

Description

This animal is known from numerous fossils, sufficiently complete to reconstruct the general appearance of the creature. It was superficially similar to a modern

prairie dog Prairie dogs (genus ''Cynomys'') are herbivorous burrowing ground squirrels native to the grasslands of North America. Within the genus are five species: black-tailed, white-tailed, Gunnison's, Utah, and Mexican prairie dogs. In Mexico, p ...

, or a slender marmot. Its body was approximately 30–40 centimeters long, excluding the tail.

Skull

The skull was short, broad, and high ; the temporal region and the tympanic bulla were enlarged. The dentition was complete, with incisor-shaped canines and without diastema. The premolars and molars were low-crowned (brachydont). The first upper incisor was well developed, and the first upper premolar was incisor-shaped. The other upper premolars were triangular in section and had a deep central dimple. The lower premolars were progressively more complex towards the posterior part of the mandible. The lower molars had a short anterior lobe and a posterior lobe with a well-developed entoconid.

Postcranial skeleton

''Notopithecus'' had an agile and lithe body, with a long tail and four strong but slender limbs, allowing this animal to move rather quickly. The calcaneus had a rather short neck and the talus was characterized by a trapezoidal and asymmetrical trochlea, similar to ''

Trachytherus ''Trachytherus'' is an extinct genus of mesotheriid notoungulate that lived from the Late Oligocene to the Early Miocene in what is now South America. Description ''Trachytherus'' had a relatively low, compact skull with an elongated snout, l ...

'', with a concave and smooth articular surface. ''Notopithecus'' also had a notable talar foramen, making its tarsus quite similar to other more specialized Typotheres, but still recalling in some way basal and archaic notoungulates, such as ''

Colbertia ''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. Description This animal was roughly the size of a Virginia ...

'', notably with the well-developed fibular tubercle of the calcaneus, in the lack of talar-cuboid contact and in the presence of a talar foramen.

Description

''Notopithecus'' was first described in 1897 by Florentino Ameghino, based on fossil remains found in Middle Eocene terrains of the Gran Barranca locality of the

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), 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- ...

in Argentina. The type species is ''Notopithecus adapinus'', later uncovered in several other Middle Eocene sites elsewhere in Argentina. The species ''Adpithecus amplidens'', from the Late Eocene, and described by Ameghino in 1901, was later attributed to the genus. ''Notopithecus'' was initially considered as a basal primate by Ameghino, confusion still found in the genus name, "''Notopithecus''" meaning "Monkey of the South". Later, it was determined that it was a Notoungulate belonging to the suborder

, a group of mammals sharing similarities with rodents. ''Notopithecus'' was a member of the eponymous archaic subfamily Notopithecinae, and is usually nested as a basal member of the family

Interatheriidae Interatheriidae is an extinct family of notoungulate mammals from South America. Interatheriids are known from the Middle Eocene (Mustersan) to the Early Pliocene (Montehermosan).McKenna & Bell, 1997Linares, 2004 These animals were principally sm ...

, a clade of typotheres that diversified mainly during the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

and Miocene, giving rise to genera such as ''

Interatherium ''Interatherium'' is an extinct genus of interatheriid mammal from the Early to Middle Miocene (Colhuehuapian- Mayoan). Fossils have been found in the Santa Cruz, Collón Curá and Sarmiento Formations in Argentina.Fernández, M. (2015). Re ...

'', ''

Protypotherium ''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 ...

'', '' Miocochilius'' and '' Cochilius''. More recently, some studies tends to indicate that ''Notopithecus'' was nested, along with ''

Transpithecus ''Transpithecus'' is an extinct genus of Notoungulates, belonging to the suborder Typotheria. It lived during the Middle Eocene in what is today South America. Description This animal may have been vaguely similar to a marmot, and could r ...

'', within a different family, Notopithecidae, not including "true" interatheriids.B. Vera. 2016. Phylogenetic revision of the South American notopithecines (Mammalia: Notoungulata). Journal of Systematic Palaeontology 14(6):461-480

Paleobiology

''Notopithecus'' was a terrestrial animal whose brachydont teeth were well suited to eat low fern fronds and tender leaves.

Bibliography

*F. Ameghino. 1897. Mamiferos Cretaceos de la Argentina. Segunda contribucion al conocimiento de la fauna mastologica de las capas con restos de Pyrotherium. Boletin Instituto Geografico Argentino 18:406-521 *F. Ameghino. 1901. Notices préliminaires sur des ongulés nouveaux des terrains crétacés de Patagonie reliminary notes on new ungulates from the Cretaceous terrains of Patagonia Boletin de la Academia Nacional de Ciencias de Córdoba 16:349-429 *M. A. Reguero and F. J. Prevosti. 2010. Rodent-like notoungulates (Typotheria) from Gran Barranca, Chubut Province, Argentina: phylogeny and systematics. In R. H. Madden, A. A. Carlini, M. G. Vucetich, R. F. Kay (eds.), The Paleontology of Gran Barranca: Evolution and Environmental Change through the Middle Cenozoic of Patagonia 148–165 {{Taxonbar, from=Q56254608 Typotheres Eocene mammals of South America Paleogene Argentina Fossils of Argentina Fossil taxa described in 1887 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Sarmiento Formation