OLD WORLD MONKEYS
Old World Monkeys are grouped together with apes in the infra-order Catarrhini because the nostrils of both groups are narrow and close together. The name catarrhine literally means ‘drooping nose’. Within the infraorder Catarrhini, monkeys are assigned to the Superfamily Cercopithecoidea, while apes and humans are assigned to the superfamily Hominoidea. The two lineages of modern catarrhine monkeys are assigned to a single family, the family Cercopithecidae.
Old World Monkeys are found in Africa, Asia and Gibraltar, hence the term ‘Old World’. They tend to be larger than New World monkeys. As a group, these monkeys show a shortening of the face with the nostrils becoming one unit. The upper lip is enlarged and has muscles which help in feeding, facial expression and vocalisation. Cercopithecines have well developed opposable thumbs and big toes which grip well. Their fore limbs and hind limbs are usually the same length. Their tails may be very long but are not prehensile, some have reduced tails or even lack tails. Some are arboreal, many species are terrestrial. They have hard pads on the lower sides of their buttocks for sitting on – the ischial callosities. Old World monkeys are more sexually dimorphic than New World monkeys: males are larger, genders may differ in colour, the males’ skulls and canine teeth are larger than the females’.
SKULLS AND DENTITION
THE TWO LINEAGES OF THE OLD WORLD MONKEYS
Modern catarrhine monkeys belong to a single family, the family Cercopithecidae, whose members are divided between the subfamilies Cercopithecinae and Colobinae. The subfamily Cercopithecinae contains 45 species of cheek pouch or ‘typical’ monkeys. Guenons, baboons and macaques are distinguished by the possession of cheek pouches for storing and carrying food. The sub-family Colobinae contains 37 species of leaf-eating monkeys. Colobus monkeys, leaf monkeys and langurs are distinguished by the possession of a sacculated stomach in which leaves are digested by bacterial fermentation.