The simians, anthropoids, or higher primates are an infraorder (Simiiformes ) of

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 ...

s containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders Platyrrhini (New World monkeys) and Catarrhini, the latter of which consists of the family Cercopithecidae ( Old World monkeys in the stricter sense) and the superfamily Hominoidea (apesincluding humans). The simians are sister group to the tarsiers (Tarsiiformes), together forming the haplorhines. The

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

occurred about 60 million years ago (during the Cenozoic era); 40 million years ago, simians colonized South America, giving rise to the New World monkeys. The remaining simians (catarrhines) split about 25 million years ago into Cercopithecidae and apes (including

human Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

s).

Taxonomy

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 Prosimians are a group of primates that includes all living and extinct Strepsirrhini, strepsirrhines (lemurs, Lorisoidea, lorisoids, and Adapiformes, adapiforms), as well as the Haplorhini, haplorhine tarsiers and their extinct relatives, the Om ...

" is still regularly found in textbooks and the academic literature because of familiarity, a condition likened to the use of the

metric system The metric system is a system of measurement that standardization, standardizes a set of base units and a nomenclature for describing relatively large and small quantities via decimal-based multiplicative unit prefixes. Though the rules gover ...

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. Hoffstetter also argued that Simiiformes is also constructed like a proper infraorder name (ending in "iformes"), whereas Anthropoidea ends in -"oidea", which is reserved for superfamilies. He also noted that Anthropoidea is too easily confused with "anthropoïdes", which translates to "apes" from several languages. Some lines of extinct simian also are either placed into the Eosimiidae (to reflect their

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 ...

origin) and sometimes in Amphipithecidae, thought to originate in the

Early Oligocene The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

. Additionally, '' Phileosimias'' is sometimes placed in the Eosimiidae and sometimes categorised separately.

Evolution

The origin of anthropoid primates was initially thought to be Africa, however, fossil evidence now suggests they originated in Asia. During the middle to late

, 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

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 ...

s ** Suborder Strepsirrhini: non tarsier 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. 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, and '' Nosmips aenigmaticus'' (previously in Eosimidae) is a basal simian. In a 2021 paper, the following basal simians were found: ''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 ou
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. The earliest anthropoids were small primates with varied diets, forward-facing eyes, acute color vision for daytime lifestyles, and brains devoted more to vision and less to smell. Living simians in both the New World and the Old World have larger brains than other primates, but they evolved these larger brains independently. Simians characteristically have relatively large brains, fused mandibles, binocular and color vision, and the females have a single fused uterus.Henry R. Hermann Ph.D., in Dominance and Aggression in Humans and Other Animals, 2017 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.

References

External links