Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons (genus Papio), red colobus (genus Piliocolobus) and macaques (genus Macaca). Common names for other Old World monkeys include the talapoin, guenon, colobus, douc (douc langur, genus Pygathrix), vervet, gelada, mangabey (a group of genera), langur, mandrill, surili (Presbytis), patas, and proboscis monkey. Phylogenetically, they are more closely related to apes than to New World monkeys. They diverged from a common ancestor of New World monkeys around 45 to 55 million years ago.
The smallest Old World monkey is the talapoin, with a head and body in length, and weighing between . The largest is the male mandrill, around in length, and weighing up to Old World monkeys have a variety of facial features; some have snouts, some are flat-nosed, and many exhibit coloration. Most have tails, but they are not prehensile.
Old World monkeys are native to Africa and Asia today, inhabiting numerous environments: tropical rain forests, savannas, shrublands, and mountainous terrain. They inhabited much of Europe in the past; today, the only survivors in Europe are the Barbary macaques of Gibraltar. Whether they were native to Gibraltar or were brought by humans is unknown.
Some Old World monkeys are arboreal, such as the colobus monkeys; others are terrestrial, such as the baboons. Most are at least partially omnivorous, but all prefer plant matter, which forms the bulk of their diets. Most are highly opportunistic, primarily eating fruit, but also consuming almost any food item available, such as flowers, leaves, bulbs and rhizomes, insects, snails, small mammals, and garbage and handouts from humans.
Taxonomic classification and phylogeny
Two subfamilies are recognized, the Cercopithecinae, which are mainly African, but include the diverse genus of macaques, which are Asian and North African, and the Colobinae, which includes most of the Asian genera, but also the African colobus monkeys.
The Linnaean classification beginning with the superfamily is: Superfamily Cercopithecoidea Family Cercopithecidae: Old World monkeys Subfamily Cercopithecinae Tribe Cercopithecini Genus Allenopithecus – Allen's swamp monkey Genus Miopithecus – talapoins Genus Erythrocebus – patas monkeys Genus Chlorocebus Genus Cercopithecus – guenons Genus Allochrocebus – terrestrial guenons Tribe Papionini Genus Macaca – macaques Genus Lophocebus – crested mangabeys Genus Rungwecebus – kipunji Genus Papio – baboons Genus Theropithecus – gelada Genus Cercocebus – white-eyelid mangabeys Genus Mandrillus – mandrill and drill Subfamily Colobinae African group Genus Colobus – black-and-white colobuses Genus Piliocolobus – red colobuses Genus Procolobus – olive colobus Langur (leaf monkey) group Genus Semnopithecus – gray langurs or Hanuman langurs Genus Trachypithecus – lutungs Genus Presbytis – surilis Odd-nosed group Genus Pygathrix – doucs Genus Rhinopithecus – snub-nosed monkeys Genus Nasalis – proboscis monkey Genus Simias – pig-tailed langur
The distinction between apes and monkeys is complicated by the traditional paraphyly of monkeys: Apes emerged as a sister group of Old World monkeys in the catarrhines, which are a sister group of New World monkeys. Therefore, cladistically, apes, catarrhines and related contemporary extinct groups, such as Parapithecidae, are monkeys as well, for any consistent definition of "monkey".
"Old World monkey" may also legitimately be taken to be meant to include all the catarrhines, including apes and extinct species such as Aegyptopithecus, in which case the apes, Cercopithecoidea and Aegyptopithecus as well as (under an even more expanded definition) even the Platyrrhini emerged within the Old World monkeys. Historically, monkeys from the "Old World" (Afro-Arabia), somehow drifted to the "New World" some 40 million years ago, forming the "New World monkeys" (platyrrhines). Apes would emerge later within the Afro-Arabia group.
Characteristics
Old World monkeys are medium to large in size, and range from arboreal forms, such as the colobus monkeys, to fully terrestrial forms, such as the baboons. The smallest is the talapoin, with a head and body 34–37 cm in length, and weighing between 0.7 and 1.3 kilograms, while the largest is the male mandrill (the females of the species being significantly smaller), at around 70 cm in length, and weighing up to 50 kilograms.