monkey

Any of the various smaller, mainly tree-dwelling anthropoid primates, excluding humans and the apes. There are 125 species, living in Africa, Asia, and tropical Central and South America. Monkeys eat mainly leaves and fruit, and also small animals. Several species are endangered due to loss of forest habitat, for example the woolly spider monkey and black saki of the Amazonian forest.

Old World monkeys (family Cercopithecidae) of tropical Africa and Asia are distinguished by their close-set nostrils and differentiated thumbs, some also having cheek pouches and rumps with bare patches (callosities) of hardened skin. They include baboons, langurs, macaques, and guenons.

New World monkeys of Central and South America are characterized by wide-set nostrils, and some have highly sensitive prehensile tails that can be used as additional limbs, to grasp and hold branches or objects. They include two families:

(1) the family Cebidae, which includes the larger species saki, capuchin, squirrel, howler, and spider monkeys;

(2) the family Callithricidae, which includes the small marmosets and tamarins.