A primate is a member of the biological order Primates, the group that contains lemurs, lorids, galagos, tarsiers, monkeys, and apes, with the last category including humans.[1] With the exception of humans, who now inhabit every continent on Earth,Template:Ref label most primates live in tropical or subtropical regions of the Americas, Africa and Asia.[2] Primates range in size from the 30-gram (1 oz) Pygmy Mouse Lemur to the 200-kilogram (440 lb) Mountain Gorilla. According to fossil evidence, the primitive ancestors of primates may have existed in the late Cretaceous period around 65 mya (million years ago), and the oldest known primate is the Late Paleocene Plesiadapis, c. 55–58 mya. Molecular clock studies suggest that the primate branch may be even older, originating in the mid-Cretaceous period around 85 mya.

Evolutionary historyEdit


Rodentia (rodents)

Lagomorpha (rabbits, hares, pikas)


Scandentia (treeshrews)

Dermoptera (colugos)



The Primates order are a part of the clade Eutheria which is nested within the Euarchontoglires clade of the class Mammalia. Recent molecular genetic research on primates, colugos, and treeshrews has shown that the two species of colugos are more closely related to the primates than the treeshrews,[3] even though the treeshrews were at one time considered primates.[4] These three orders make up the Euarchonta clade. This clade combines with the Glires clade (composed of the Rodentia and Lagomorpha) to form the Euarchontoglires clade. Variously, both Euarchonta and Euarchontoglires are ranked as superorders. Also, some scientists consider Dermoptera a suborder of Primates and call the "true" primates the suborder Euprimates.[5]


The primate lineage is thought go back to at least 65 Mya, even though the oldest known primate from the fossil record is Plesiadapis (c. 55–58 mya) from the Late Paleocene.[6][7] Other studies, including molecular clock studies, have estimated the origin of the primate branch to have been in the mid-Cretaceous period, around 85 mya.[8][9][10]

In modern cladistic reckonings, the Primates order is monophyletic. The suborder Strepsirrhini, the "wet-nosed" primates, is generally thought to have split off from the primitive primate line about 63 mya (million years ago),[11] although earlier dates are also supported.[12] The seven strepsirhine families are the four related lemur families and the three remaining families that include the Aye-aye, the lorids, and the galagos.[13] Older classification schemes wrap the Lepilemuridae into the Lemuridae and the Galagidae into the Lorisidae, yielding a three-two family split instead of the four-three split as presented here.[13] During the Eocene, most of the northern continents were dominated by two groups, the adapids and the omomyids.[14][15] The former is considered a member of Strepsirrhini, but it does not have a toothcomb like modern lemurs. The latter was related closely to tarsiers, monkeys, and apes. It is unclear exactly how these two groups relate to extant primates. Omomyids perished about 30 mya,[15] while Adapids survived until about 10 mya.[16]

According to genetic studies, the lemurs of Madagascar diverged from the lorisiforms approximately 75 mya.[12] These studies, as well as chromosomal and molecular evidence, also show that lemurs are more closely related to each other than to other strepsirrhine primates.[12][17] However, Madagascar split from Africa at 160 mya and from India at 90 mya.[18] For lemurs to be more closely related to each other than other strepsirrhine primates, it is thought that a very small ancestral population came to Madagascar via a single rafting event between 50 and 80 million years ago.[12][17][18] Other colonization options have been examined, such as multiple colonizations from Africa and India, but none are supported by the genetic and molecular evidence.[14]

Until recently the Aye-aye has been difficult to place within Strepsirrhini.[13] Theories had been proposed that its family, Daubentoniidae, was either a lemuriform primate (meaning its ancestors split from lemur line more recently than the lemurs and lorises split) or a sister group to all the other strepsirrhines. In 2008, the Aye-aye family (Daubentoniidae) was confirmed to be a lemuriform and descended from the same ancestral lemur population that rafted to the island, it is contained within the Chiromyiformes infraorder, forming a sister clade to the lemurs.[12]

The suborder Haplorrhini, the "dry-nosed" primates, is composed of two sister clades.[13] The prosimian tarsiers in family Tarsiidae (monotypic in its own infraorder Tarsiiformes), represent the most primitive division at about 58 mya.[19][20] The Simiiformes infraorder emerged about 40 mya,[15] and contains the two clades: the parvorder Platyrrhini that developed in South America and contains New World monkeys, and the parvorder Catarrhini that developed in Africa and contains the Old World monkeys, humans and the other apes.[13] A third clade, which included the eosimiids, developed in Asia but went extinct millions of years ago.[21]

See alsoEdit


  1. ^ Goodman, M., Tagle, D. A., Fitch, D. H., Bailey, W., Czelusniak, J., Koop, B. F., Benson, P., Slightom, J. L. (1990). "Primate evolution at the DNA level and a classification of hominoids". Journal of Molecular Evolution 30: 260–266. doi:10.1007/BF02099995. 
  2. ^ Cite error: Invalid <ref> tag; no text was provided for refs named britannica
  3. ^ Janečka, J. E.; Miller, W., Pringle, T. H., Wiens, F., Zitzmann, A., Helgen, K. M., Springer, M. S. & Murphy, W. J. (2007). "Molecular and Genomic Data Identify the Closest Living Relative of Primates". Science 318 (5851): 792–794. doi:10.1126/science.1147555. Retrieved on 2008-08-17. 
  4. ^ Kavanagh, M. (1983). A Complete Guide to Monkeys, Apes and Other Primates. New York: Viking Press. pp. 18. ISBN 0670435430. 
  5. ^ McKenna, M. C. and Bell, S. K. (1997). Classification of Mammals Above the Species Level. New York: Columbia University Press. pp. 329. ISBN 023111012X. 
  6. ^ "Nova - Meet Your Ancestors". PBS. Retrieved on 2008-10-24. 
  7. ^ "Plesiadapis" (PDF). North Dakota Geological Survey. Retrieved on 2008-10-24. 
  8. ^ Lee, M. (September 1999). "Molecular Clock Calibrations and Metazoan Divergence Dates". Journal of Molecular Evolution 49 (3): 385–391. doi:10.1007/PL00006562. 
  9. ^ "Scientists Push Back Primate Origins From 65 Million To 85 Million Years Ago". Science Daily. Retrieved on 2008-10-24. 
  10. ^ Tavaré, S., Marshall, C. R., Will, O., Soligo, C. & Martin R.D. (April 18, 2002). "Using the fossil record to estimate the age of the last common ancestor of extant primates". Nature 416 (6882): 726–729. doi:10.1038/416726a. 
  11. ^ Klonisch, T., Froehlich, C., Tetens, F., Fischer, B. & Hombach-Klonisch, S. (2001). "Molecular Remodeling of Members of the Relaxin Family During Primate Evolution". Molecular Biology and Evolution 18: 393–403. Retrieved on 2008-08-22. 
  12. ^ a b c d e Horvath, J. et al. (2008). "Development and Application of a Phylogenomic Toolkit: Resolving the Evolutionary History of Madagascar's Lemurs" (PDF). Genome Research 18: 490. doi:10.1101/gr.7265208. Retrieved on 2008-08-22. 
  13. ^ Cite error: Invalid <ref> tag; no text was provided for refs named MSW3
  14. ^ a b Sellers, Bill (2000-10-20). "Primate Evolution" (PDF). University of Edinburgh. 13-17. Archived from the original on 2008-10-29. Retrieved on 2008-10-23. 
  15. ^ a b c Hartwig, W. (2007). "Primate Evolution". in Campbell, C., Fuentes, A., MacKinnon, K., Panger, M. & Bearder, S.. Primates in Perspective. Oxford University Press. pp. 13–17. ISBN 978-0-19-517133-4. 
  16. ^ Ciochon, R. & Fleagle, J. (1987). Primate Evolution and Human Origins. Menlo Park, California: Benjamin/Cummings. pp. 72. ISBN 9780202011752. 
  17. ^ a b Garbutt, N. (2007). Mammals of Madagascar, A Complete Guide. A&C Black Publishers. pp. 85–86. ISBN 978-0-300-12550-4. 
  18. ^ a b Mittermeier, R.A.; et al. (2006). Lemurs of Madagascar (2nd Edition ed.). Conservation International. pp. 23–26. ISBN 1-881173-88-7. 
  19. ^ Shekelle, M. (2005). "Evolutionary Biology of Tarsiers".. Retrieved on 2008-08-22. 
  20. ^ Schmidt, T. et al. (2005). "Rapid electrostatic evolution at the binding site for cytochrome c on cytochrome c oxidase in anthropoid primates". Proceedings of the National Academy of Sciences of the United States of America 102 (18): 6379–6384. doi:10.1073/pnas.0409714102. Retrieved on 2008-08-22. 
  21. ^ Marivaux, L. et al. (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. doi:10.1073/pnas.0503469102. Retrieved on 2008-08-22. 

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