''Altiatlasius'' is an extinct genus of

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 ...

, which may have been the oldest known

primate Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...

, dating to the Late

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

(c.57 ma) from

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

. The only species, ''Altiatlasius koulchii'', was described in 1990. Its true taxonomic position remains controversial. It has also been suggested that it should be classified as a plesiadapiform (an extinct group of arboreal mammal thought to be ancestral to primates) or that it should be recognized as a euprimate, either as an omomyid (a branch of fossil primates thought to be closely related to

tarsier Tarsiers ( ) are haplorhine primates of the family Tarsiidae, which is the lone extant family within the infraorder Tarsiiformes. Although the group was prehistorically more globally widespread, all of the existing species are restricted to M ...

s), an early tarsiiform, or the oldest

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

simian The simians, anthropoids, or higher primates are an infraorder (Simiiformes ) of primates containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders New World monkey, Platyrrhini (New World mon ...

(monkeys and apes).

Evolutionary history and taxonomy

''Altiatlasius koulchii'', potentially the oldest known euprimate, is known only from ten isolated upper and lower

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

and a fragment of a

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. These fossils date to the Late

, approximately 57 million years ago, and come from the Jbel Guersif Formation in the Ouarzazate Basin of

. First described in 1990 by Sigé ''et al.'', ''Altiatlasius'' was originally proposed to be an omomyid, possibly close to the split with

s (monkeys and apes). It has also been classified in the family Toliapinidae, a type of plesiadapiform found in Europe. Other classifications assume they are

euprimates, eosimiid-like simians, or an early tarsiiform. Many authorities consider ''Altiatlasius'' to be the oldest stem simian. Godinot (1994) and Bajpai ''et al''. (2008) both support the view that it is an early anthropoid (simian). Together with the Early to Middle

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

fossil primate '' Algeripithecus'' (originally thought to be the oldest

crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, parti ...

simian) from

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

, ''Altiatlasius'' helped strengthen the argument for an African origin of simian primates. However, when additional fossil remains of ''Algeripithecus'' were found, it was shown to be a

strepsirrhine Strepsirrhini or Strepsirhini (; ) is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and Southeast Asia. Colle ...

primate instead of a haplorhine, placing it with the azibiids, a group thought to be most closely related to lemuriforms (living

lemur Lemurs ( ; from Latin ) are Strepsirrhini, wet-nosed primates of the Superfamily (biology), superfamily Lemuroidea ( ), divided into 8 Family (biology), families and consisting of 15 genera and around 100 existing species. They are Endemism, ...

s and lorisoids). Because ''Algeripithecus'' was radically reclassified with the discovery of more fossils, equally fragmentary remains of ''Altiatlasius'' leave its

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

affinities questionable. Also, the 20 million year gap in the fossil record between ''Altiatlasius'' and the first parapithecoids raises questions about the validity of the African origins hypothesis for simians.

Notes

References

Literature cited

* * * * ** * {{Taxonbar, from=Q627032 Paleocene mammals Monotypic prehistoric primate genera Paleocene mammals of Africa Fossil taxa described in 1990