The simians, anthropoids, or higher primates are an infraorder (Simiiformes /ˈsɪmi.ɪfɔːrmz/) of primates 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 (apes – including humans).

Temporal range: Middle Eocene-Holocene, 40–0 Ma
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Haeckel, 1866[1][2][3]

sister: Tarsiiformes


The simians are sister group to the tarsiers (Tarsiiformes), together forming the haplorhines. The radiation 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 humans).

Taxonomy and evolution


In earlier classification, New World monkeys, Old World monkeys, apes, and humans – collectively known as simians or anthropoids – were grouped under Anthropoidea (/ˌænθrəˈpɔɪdi.ə/; from Ancient Greek ἄνθρωπος (ánthrōpos) 'human', and -οειδής (-oeidḗs) 'resembling, connected to, etc.'), 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.[5] 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.[6] 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.[7] In the Anthropoidea, evidence indicates that the Old World and New World primates went through parallel evolution.[8]

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.[1][9] In contrast, Anthropoidea by Mivart dates to 1864,[10] while Simiiformes by Haeckel dates to 1866, leading to counterclaims of priority.[1] 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.[9]

Extant simians are split into two distinct groups. 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. This shows that the Cercopithecidae are closer related to the apes than to the Platyrrhini.

Some lines of extinct simian also are either placed into the Eosimiidae (to reflect their Eocene origin) and sometimes in Amphipithecidae, thought to originate in the Early Oligocene. Additionally, Phileosimias is sometimes placed in the Eosimiidae and sometimes categorised separately.[11]


Phylogeny of living (extant) primates
Primates (80 Mya)
Haplorhini (63 Mya)
Simiiformes (42.6 Mya)



Cladogram. For each clade, it is indicated approximately how many Mya newer extant clades radiated.[citation needed]

The following is the listing of the various simian families, and their placement in the order Primates:[1][2]

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.[12][13][5][14][7][15] It is indicated approximately how many Mya the clades diverged into newer clades.

Haplorhini (64)


Simians (54)
Ekgmowechashalidae (39)

Muangthanhinius (†32 Mya)


Gatanthropus micros (†30)

Bugtilemur (†29)

Ekgmowechashala (†)

Eosimiidae (52)
Eosimiidae s.s.(50)

Eosimias (†40)

Phenacopithecus (†42)


Bahinia [fr] (†32)

Nosmips aenigmaticus (†37)

Phileosimias (†28)


Amphipithecidae (†35)

Crown Simians (40)
Platyrrhini (35)

Perupithecus (†)


Chilecebus (†20)


Tremacebus (†20)


Homunculus (†16)

Dolichocebus (†20)



Usually the Ekgmowechashalidae are considered to be Strepsirrhini, not Haplorhini.[16] A 2018 study places Eosimiidae as a sister to the crown haplorhini.[17] In 2020 papers, the Proteopithecidae are part of the Parapithecoidea,[15][18] and Nosmips aenigmaticus (previously in Eosimidae[13]) is a basal simian.[18] In a 2021 paper, the following basal simians were found:[19]

Simiiformes/ (58)

Altiatlasius koulch (†57)


Nosmips aenigmaticum (†37)


Anthradapis vietnamensis (†37)

Ekgmowechashalidae (†28)


Dolichocebus annectens (†16)

Parvimico materdei (†16)


Eosimiidae s.s. (†41)


Bahinia (†33)


Phileosimias (†28)

higher Simians (incl. crown simians)

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.[6] 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.[6] Living simians in both the New World and the Old World have larger brains than other primates, but they evolved these larger brains independently.[6]

See also



  1. ^ a b c d Groves, C. P. (2005). "Simiiformes". In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. p. 128. ISBN 0-801-88221-4. OCLC 62265494.
  2. ^ a b Rylands AB, Mittermeier RA (2009). "The Diversity of the New World Primates (Platyrrhini)". In Garber PA, Estrada A, Bicca-Marques JC, Heymann EW, Strier KB (eds.). South American Primates: Comparative Perspectives in the Study of Behavior, Ecology, and Conservation. Springer. ISBN 978-0-387-78704-6.
  3. ^ a b c Haekel, Ernst (1866). Generelle Morphologie, Allgemeine Entwicklungsgeschichte der Organismen. pp. CLX.
  4. ^ Pocock, R. I. (1918-03-05). "On the External Characters of the Lemurs and of Tarsius". Proceedings of the Zoological Society of London. 88 (1–2): 19–53. doi:10.1111/j.1096-3642.1918.tb02076.x. ISSN 0370-2774.
  5. ^ a b Cartmill, M.; Smith, F. H (2011). The Human Lineage. John Wiley & Sons. ISBN 978-1-118-21145-8.
  6. ^ a b c d Williams, Blythe A; Kay, Richard F; Kirk, E Christopher (January 2010). Walker, Alan (ed.). "New perspectives on anthropoid origins". PNAS. 107 (11): 4797–4804. Bibcode:2010PNAS..107.4797W. doi:10.1073/pnas.0908320107. PMC 2841917. PMID 20212104.
  7. ^ a b Hartwig, W. (2011). "Chapter 3: Primate evolution". In Campbell, C. J.; Fuentes, A.; MacKinnon, K. C.; Bearder, S. K.; Stumpf, R. M (eds.). Primates in Perspective (2nd ed.). Oxford University Press. pp. 19–31. ISBN 978-0-19-539043-8.
  8. ^ Lull, Richard Swann (1917). "XXXVII: The Evolution of Man". Organic Evolution (1929 ed.). New York: The Macmillan Company. pp. 641–86 – via Google Books.
  9. ^ a b Hoffstetter, R. (1974). "Phylogeny and geographical deployment of the Primates". Journal of Human Evolution. 3 (4): 327–350. Bibcode:1974JHumE...3..327H. doi:10.1016/0047-2484(74)90028-1.
  10. ^ Tobias, P. V. (2002). "The evolution of early hominids". In Ingold, T (ed.). Companion Encyclopedia of Anthropology: Humanity, Culture and Social Life. Taylor & Francis. p. 35. ISBN 978-0-415-28604-6.
  11. ^ Marivaux; et al. (June 2005). "Anthropoid primates from the Oligocene of Pakistan (Bugti Hills): Data on early anthropoid evolution and biogeography". PNAS. 102 (24): 8436–41. Bibcode:2005PNAS..102.8436M. doi:10.1073/pnas.0503469102. PMC 1150860. PMID 15937103. (Full text PDF)
  12. ^ Marivaux, Laurent; Antoine, Pierre-Olivier; Baqri, Syed Rafiqul Hassan; Benammi, Mouloud; Chaimanee, Yaowalak; Crochet, Jean-Yves; Franceschi, Dario de; Iqbal, Nayyer; Jaeger, Jean-Jacques (2005-06-14). "Anthropoid primates from the Oligocene of Pakistan (Bugti Hills): Data on early anthropoid evolution and biogeography". Proceedings of the National Academy of Sciences of the United States of America. 102 (24): 8436–8441. Bibcode:2005PNAS..102.8436M. doi:10.1073/pnas.0503469102. ISSN 0027-8424. PMC 1150860. PMID 15937103.
  13. ^ a b Seiffert, Erik R.; Boyer, Doug M.; Fleagle, John G.; Gunnell, Gregg F.; Heesy, Christopher P.; Perry, Jonathan M. G.; Sallam, Hesham M. (2017-04-10). "New adapiform primate fossils from the late Eocene of Egypt". Historical Biology. 30 (1–2): 204–226. doi:10.1080/08912963.2017.1306522. ISSN 0891-2963. S2CID 89631627.
  14. ^ Ryan, Timothy M.; Silcox, Mary T.; Walker, Alan; Mao, Xianyun; Begun, David R.; Benefit, Brenda R.; Gingerich, Philip D.; Köhler, Meike; Kordos, László (2012-09-07). "Evolution of locomotion in Anthropoidea: the semicircular canal evidence". Proceedings of the Royal Society of London B: Biological Sciences. 279 (1742): 3467–3475. doi:10.1098/rspb.2012.0939. ISSN 0962-8452. PMC 3396915. PMID 22696520.
  15. ^ a b Seiffert, Erik R.; Tejedor, Marcelo F.; Fleagle, John G.; Novo, Nelson M.; Cornejo, Fanny M.; Bond, Mariano; de Vries, Dorien; Campbell, Kenneth E. (2020-04-10). "A parapithecid stem anthropoid of African origin in the Paleogene of South America". Science. 368 (6487): 194–197. Bibcode:2020Sci...368..194S. doi:10.1126/science.aba1135. ISSN 0036-8075. PMID 32273470. S2CID 215550773.
  16. ^ Ni, Xijun; Li, Qiang; Li, Lüzhou; Beard, K. Christopher (2016-05-06). "Oligocene primates from China reveal divergence between African and Asian primate evolution". Science. 352 (6286): 673–677. Bibcode:2016Sci...352..673N. doi:10.1126/science.aaf2107. ISSN 0036-8075. PMID 27151861.
  17. ^ López-Torres, Sergi; Silcox, Mary T.; Holroyd, Patricia A. (2018-09-22). "New omomyoids (Euprimates, Mammalia) from the late Uintan of southern California, USA, and the question of the extinction of the Paromomyidae (Plesiadapiformes, Primates)". Palaeontologia Electronica. 21 (3): 1–28. doi:10.26879/756. ISSN 1094-8074.
  18. ^ a b Seiffert, Erik R.; Tejedor, Marcelo F.; Fleagle, John G.; Novo, Nelson M.; Cornejo, Fanny M.; Bond, Mariano; de Vries, Dorien; Campbell, Kenneth E. (2020-04-10). "A parapithecid stem anthropoid of African origin in the Paleogene of South America". Science. 368 (6487): 194–197. Bibcode:2020Sci...368..194S. doi:10.1126/science.aba1135. ISSN 0036-8075. PMID 32273470. S2CID 215550773.
  19. ^ Wisniewski, Anna L.; Lloyd, Graeme T.; Slater, Graham J. (2022-05-25). "Extant species fail to estimate ancestral geographical ranges at older nodes in primate phylogeny". Proceedings of the Royal Society B: Biological Sciences. 289 (1975): 20212535. doi:10.1098/rspb.2021.2535. ISSN 0962-8452. PMC 9115010. PMID 35582793.
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