Simian

In earlier classification, New World monkeys, Old World monkeys, apes, and humans – collectively known as simians or anthropoids – were grouped under Anthropoidea (; ), while the strepsirrhines and tarsiers were grouped under the suborder "Prosimii". Under modern classification, the tarsiers and simians are grouped under the suborder Haplorhini, while the strepsirrhines are placed in suborder Strepsirrhini. Strong genetic evidence for this is that five SINEs are common to all haplorhines whilst absent in strepsirrhines — even one being coincidental between tarsiers and simians would be quite unlikely. Despite this preferred taxonomic division, "prosimian" is still regularly found in textbooks and the academic literature because of familiarity, a condition likened to the use of the metric system in the sciences and the use of customary units elsewhere in the United States. In the Anthropoidea, evidence indicates that the Old World and New World primates went through parallel evolution. Primatology, paleoanthropology, and other related fields are split on their usage of the synonymous infraorder names, Simiiformes and Anthropoidea. According to Robert Hoffstetter (and supported by Colin Groves), the term Simiiformes has priority over Anthropoidea because the taxonomic term Simii by van der Hoeven, from which it is constructed, dates to 1833. In contrast, Anthropoidea by Mivart dates to 1864, while Simiiformes by Haeckel dates to 1866, leading to counterclaims of priority. == Evolution ==

The origin of anthropoid primates is primarily thought by scientists to have been in Africa. However, there is also a competing theory suggesting that they may have originated in Asia. According to this latter theory, during the middle to late Eocene, multiple groups of Asian anthropoids crossed the Tethys Sea on natural rafts or floating islands, colonizing Africa alongside other Asian mammals. The earliest African anthropoid fossils appear in sites across northern Africa, including Algeria, Libya, and Egypt. This dispersal before Africa and Asia were connected by land was aided by size, Asian monsoons, and river systems. After reaching Africa, anthropoids underwent major evolutionary changes, with some groups later crossing the South Atlantic to establish the New World monkey lineage in South America. The New World monkeys in parvorder Platyrrhini split from the rest of the simian line about 40 million years ago (mya), leaving the parvorder Catarrhini occupying the Old World. This latter group split about 25 mya between the Cercopithecidae and the apes, making Cercopithecidae more closely related to the apes than to the Platyrrhini. ==Classification==

The following is the listing of the various simian families, and their placement in the order Primates: • Order Primates • Suborder Strepsirrhini: nontarsier prosimians • Suborder Haplorhini: tarsiers and monkeys, including apes • Infraorder Tarsiiformes • Infraorder Simiiformes • Parvorder Platyrrhini: New World monkeys • Family Callitrichidae: marmosets and tamarins • Family Cebidae: capuchins and squirrel monkeys • Family Aotidae: night or owl monkeys (douroucoulis) • Family Pitheciidae: titis, sakis, and uakaris • Family Atelidae: howler, spider, and woolly monkeys • Parvorder Catarrhini • Superfamily Cercopithecoidea: Old World monkeys • Family Cercopithecidae • Superfamily Hominoidea • Family Hylobatidae: gibbons • Family Hominidae: great apes, including humans • †Amphipithecidae • †Eosimiidae • †Aseanpithecus Below is a cladogram with some of the extinct simian species with the more modern species emerging within the Eosimiidae. The simians originated in Asia, while the crown simians were in Afro-Arabia. It is indicated approximately how many Mya the clades diverged into newer clades. }}}}|label1=Haplorhini (64)|style1=line-height:80%;font-size:80%}} Usually the Ekgmowechashalidae are considered to be Strepsirrhini, not Haplorhini. A 2018 study places Eosimiidae as a sister to the crown haplorhini. In 2020 papers, the Proteopithecidae are part of the Parapithecoidea, }} }} }} }} }} }} }}|label1=Simiiformes/ (58)|style1=line-height:80%;font-size:80%|sublabel1=Eosimiidae s.l.}} Dolichocebus annectens and Parvimico materdei would normally, given their South American location and their age and other factors, be considered Platyrrhini. The original Eosmiidae appear polyphyletic with Nosmips, Bahinia, and Phileosimias at different locations from other eosimians. ==Biological key-features==

In a section of their 2010 assessment of the evolution of anthropoids (simians) entitled "What is an Anthropoid", Williams, Kay, and Kirk set out a list of biological features common to all or most anthropoids, including genetic similarities, similarities in eye location and the muscles close to the eyes, internal similarities between ears, dental similarities, and similarities on foot bone structure. They also have fewer teeth and are more sexually dimorphic in terms of body size and anatomy. The traits that separate New World simians from Old World simians are the nostrils and their dentation. New World simians have broad noses with forward facing nostrils and three premolars in each quadrant of the mouth, while Old World simians have narrower noses with downward facing nostrils and a narrow septum and only have two premolars. ==See also==