Platyrrhini is derived from theGreek for "broad nosed", and their noses are flatter than those of other simians, with sideways-facing nostrils. Monkeys in the family Atelidae, such as thespider monkey, are the only primates to haveprehensile tails. New World monkeys' closest relatives are the othersimians, theCatarrhini ("down-nosed"), comprisingOld World monkeys andapes. New World monkeys descend from African simians that colonized South America, a line that split off about 40 million years ago.[4]
About 40 million years ago, theSimiiformes infraorder split into the parvorders Platyrrhini (New World monkeys) andCatarrhini (apes andOld World monkeys) somewhere on the African continent.[5] Platyrrhini are currently conjectured to have dispersed toSouth America on araft of vegetation across the Atlantic Ocean during theEocene epoch, possibly via several intermediate now submerged islands. Several other groups of animals made the same journey across the Atlantic, notably includingcaviomorph rodents.[6][7] At the time the New World monkeys dispersed to South America, theIsthmus of Panama had not yet formed, soocean currents, unlike today, favoured westward dispersal, the climate was quite different, and the width of the Atlantic Ocean was less than the present 2,800 km (1,700 mi) width by about a third (possibly 1,000 km (600 mi) less, based on the current estimate of the Atlanticmid-ocean ridge formation processes spreading rate of 25 millimetres per year (1 in/year)).[6]
The non-platyrrhiniUcayalipithecus of Amazonian Peru who might have rafted across the Atlantic between ~35–32 million years ago, are nested within the extinctParapithecoidea from theEocene of Afro-Arabia, suggesting that there were at least two separate dispersal events of primates to South America,[8]Parvimico andPerupithecus from Peru appear to be at the base of the Platyrrhini,[9] as areSzalatavus,Lagonimico, andCanaanimico.[10]
Possible evidence for a third transatlantic dispersal event comes from a fossil molar belonging toAshaninkacebus simpsoni, which has strong affinities with stemanthropoid primates of South Asian origin, theEosimiidae.[11]
The chromosomal content of the ancestor species appears to have been 2n = 54.[12] In extant species, the 2n value varies from 16 in thetiti monkey to 62 in thewoolly monkey.
ABayesian estimate of the most recent common ancestor of the extant species has a 95%credible interval of27 million years ago-31 million years ago.[13]
The following is the listing of the various platyrrhine families, as defined by Rylands & Mittermeier (2009),[2] and their position in the Order Primates:[1]
The arrangement of the New World monkey families, indeed the listing of which groups consist of families and which consist of lower taxonomic groupings, has changed over the years. McKenna & Bell (1997) used two families: Callitrichidae and Atelidae, with Atelidae divided into Cebinae, Pitheciinae, and Atelinae.[14]Rosenberger (2002 following Horowitz 1999) demoted Callitrichidae to a subfamily, putting it under the newly raised Cebidae family.[15]Groves (2005) used four families, but as a flat structure.[1]
One possible arrangement of the five families and their subfamilies of Rylands & Mittermeier can be seen in Silvestroet al. (2017):[10]
New World monkeys are small to mid-sized primates, ranging from thepygmy marmoset (the world's smallest monkey), at 14 to 16 cm (5.5 to 6.5 in) and a weight of 120 to 190 g (4.2 to 6.7 oz), to thesouthern muriqui, at 55 to 70 cm (22 to 28 in) and a weight of 12 to 15 kg (26 to 33 lb). New World monkeys differ slightly fromOld World monkeys in several aspects. The most prominent phenotypic distinction is the nose, which is the feature used most commonly to distinguish between the two groups. The clade for New World monkeys, Platyrrhini, means "flat nosed". The noses of New World monkeys are flatter than the narrow noses of Old World monkeys, and have side-facing nostrils.
New World monkeys are the only monkeys withprehensile tails—in comparison with the shorter, non-grasping tails of the anthropoids of the Old World. Prehensility has evolved at least two distinct times in platyrrhines, in the Atelidae family (spider monkeys, woolly spider monkeys, howler monkeys, and woolly monkeys), and in capuchin monkeys (Cebus).[16] Although prehensility is present in all of these primate species, skeletal and muscular-based morphological differences between these two groups indicate that the trait evolved separately through convergent evolution.[17][18] The fully prehensile tails that have evolved in Atelidae allow the primates to suspend their entire body weight by only their tails, with arms and legs free for other foraging and locomotive activities.[19] Semi-prehensile tails inCebus can be used for balance by wrapping the tail around branches and supporting a large portion of their weight.[20]
New World monkeys (except for thehowler monkeys of genusAlouatta)[21] also typically lack thetrichromatic vision of Old World monkeys.[22] Colour vision in New World primates relies on a single gene on theX-chromosome to produce pigments that absorb medium and long wavelength light, which contrasts with short wavelength light. As a result, males rely on a single medium/long pigment gene and aredichromatic, as arehomozygous females.Heterozygous females may possess two alleles with different sensitivities within this range, and so can displaytrichromatic vision.[23]
Platyrrhines also differ from Old World monkeys in that they have twelvepremolars instead of eight; having adental formula of2.1.3.32.1.3.3 or2.1.3.22.1.3.2 (consisting of 2 incisors, 1 canine, 3 premolars, and 2 or 3 molars). This is in contrast with Old World Anthropoids, includinggorillas,chimpanzees,bonobos,siamangs,gibbons,orangutans, and mosthumans, which share a dental formula of2.1.2.32.1.2.3. Many New World monkeys are small and almost all arearboreal, so knowledge of them is less comprehensive than that of the more easily observed Old World monkeys. Unlike most Old World monkeys, many New World monkeys formmonogamouspair bonds, and show substantialpaternal care of young.[24] They eat fruits, nuts, insects, flowers, bird eggs, spiders, and small mammals. Unlike humans and most Old World monkeys, their thumbs are notopposable[25] (except for somecebids).
^abOliveira, Felipe Bandoni de; Molina, Eder Cassola; Marroig, Gabriel (2009). "Paleogeography of the South Atlantic: a Route for Primates and Rodents into the New World?".South American Primates. New York: Springer. pp. 55–68.doi:10.1007/978-0-387-78705-3_3.ISBN978-0-387-78704-6.
^Seiffert, Erik R.; Tejedor, Marcelo F.; Fleagle, John G.; Novo, Nelson M.; Cornejo, Fanny M.; Bond, Mariano; de Vries, Dorien; Campbell Jr., Kenneth E. (2020). "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.PMID32273470.S2CID215550773.
^Vries, Dorien de; Beck, Robin M. D. (2021-10-22). "Total evidence tip-dating phylogeny of platyrrhine primates and 27 well-justified fossil calibrations for primate divergences".bioRxiv10.1101/2021.10.21.465342.
^abSilvestro, Daniele; Tejedor, Marcelo F.; Serrano Serrano, Martha L.; Loiseau, Oriane; Rossier, Victor; Rolland, Jonathan; Zizka, Alexander; Antonelli, Alexandre; Salamin, Nicolas (2017). "Evolutionary history of New World monkeys revealed by molecular and fossil data".bioRxiv10.1101/178111.
^de Oliveira EH, Neusser M, Müller S (2012). "Chromosome evolution in New World Monkeys (Platyrrhini)."Cytogenetic and Genome Researchhttps://doi.org/10.1159/000339296
^Perez SI, Tejedor MF, Novo NM, Aristide L (2013) "Divergence times and the evolutionary radiation of New World monkeys (Platyrrhini, Primates): An analysis of fossil and molecular Data".PLoS One 8(6):e68029.
^McKenna, M. C.; Bell, S. K., eds. (1997).Classification of mammals – above the species level. New York: Columbia University Press. pp. xii-631.
^Rosenberger, A. L. (2002). "Platyrrhine paleontology and systematics: the paradigm shifts". In Hartwig, W. C. (ed.).The Primate Fossil Record. Cambridge, England: Cambridge University Press. pp. 151–159.Bibcode:2002prfr.book.....H.
^Emmons, L. H.; Gentry, A. H. (1983). "Tropical Forest Structure and the Distribution of Gliding and Prehensile-Tailed Vertebrates".The American Naturalist.121 (4):513–524.doi:10.1086/284079.ISSN0003-0147.JSTOR2460978.S2CID85211169.
Opazo, J. C.; et al. (2006). "Phylogenetic relationships and divergence times among New World monkeys (Platyrrhini, Primates)".Molecular Phylogenetics and Evolution.40 (1):274–280.doi:10.1016/j.ympev.2005.11.015.PMID16698289.
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