Cebid refers to Cebidae, a family of New World monkeys distributed throughout Latin America. The family consists of three extant (living) subfamilies and eight genera that have been in South America since the Oligocene (about 3 million years ago). Cebids have long hairy tails used for counterbalance. Some species have semiprehensile tails, which are hairless on the bottom tip and can be used as a fifth limb.
The first subfamily, Aotinae, includes one genus, Aotus. The common name for this genus is owl monkey, night monkey, or douracouli. The name owl monkey comes from the low, owl-like hoots that the monkeys make, possibly to attract mates and/or maintain contact during nighttime foraging. Owl monkeys are the only higher primates that are nocturnal, and as a result, they have the largest sized orbits of any anthropoid (higher primate). Owl monkeys weigh around 1 kg and have slightly opposable thumbs. They are monomorphic, with males and females having similar body sizes. Owl monkeys live in monogamous families, and infants spend most of their time with the father, who carries them around and sleeps with them. However, unlike most monogamous primates, owl monkeys rarely groom each other. They are arboreal and eat mostly fruit, but also eat leaves and insects.
The second subfamily, Callithrichinae, is made up of three groups, the tamarins (Saguinus, Leontopithecus), marmosets (Callithrix, Cebuella), and Goeldi’s monkeys (Callimico). Callitrichines are the smallest of the New World monkeys, weighing between 100 and 750 g. They often have brightly colored manes, moustaches, and coats. Although uncommon in higher primates, callithrichines have derived claws instead of nails, which allow them to cling to tree trunks to feed on exudates, insects, and fruits. Marmosets and tamarins usually give birth to dizygotic twins, while Goeldi’s monkeys have single births. Although mating systems vary among callitrichines, many groups are polyandrous and contain a single breeding female and several adult males that help care for the young. Callitrichines can live in marginal and disturbed habitats.
The third subfamily is Cebinae, which consists of the capuchin monkeys (Cebus) and squirrel monkeys (Saimiri). Capuchins weigh an average of 3,000 g and live in multimale-multifemale groups of 8 to 30 individuals. They are arboreal and normally feed on many different types of fruits, leaves, and animal matter. Some capuchins use their proportionately large brains to obtain food not available to other species, such as the tufted capuchins’ ability to break open the hard shells of palm nuts. Squirrel monkeys are smaller than capuchins, weighing between 554 and 1,250 g. They live in groups of 20 to over 50 individuals and are frugivorous and insectivorous. Squirrel monkeys, unlike capuchins, which have semiprehensile tails, have prehensile tails only as juveniles. In addition, squirrel monkeys often are used as laboratory animals. Furthermore, both squirrel monkeys and capuchins are easily recognized as pets on television, in films, and other forms of entertainment. A handful of Cebids are classified as vulnerable, endangered, or critically endangered due to deforestation of vital habitat.
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