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Marmosets and Tamarins

Marmosets, Tamarins, The Odd Ones

Marmosets and tamarins are South and Central American primates of the Amazon Basin. Their family, Callitrichidae, includes 18 species that have been described as "near"-monkeys. All species are considered endangered or threatened by extinction. This plight is mostly caused by deforestation to develop new agricultural land, as well as disturbance of their forest habitat by logging, road construction, hunting, and other human activities.

The two groups of small, furry near-monkeys are extremely similar, but the marmosets (mostly in the genus Callithrix) and the tamarins (genus Saguinus) are located in different regions, overlapping in only one area near the mouth of the Amazon River.

The lower jaw of marmosets is V-shaped, making their face pointed, while that of tamarins is rounded into a U-shape. Marmosets have elongated lower incisor teeth, which are about the same length as their incisors; for this reason they are sometimes called short-tusked marmosets. The tamarins have canine teeth longer than the incisors, and are called long-tusked marmosets.

Marmosets and tamarins feed on the gum and sap of trees, which they obtain by scraping the bark with their teeth. All other primates that eat gum or sap use holes dug by insects. Marmosets and tamarins also eat fruit, flowers, and insects.

Most marmosets and tamarins have a head-and-body length of 7-12 in (17-30 cm), plus a tail about 3 in (7.5 cm) longer than that. The tail is not prehensile, or capable of grasping. Unlike many other monkeys, marmosets and tamarins do not have an opposable thumb. Their sharp, curved claws allow these lightweight monkeys to hold onto tree branches. Only the great toe bears a nail instead of a claw.

Their face has little or no fur, but there can be large tufts of dense hair coming from the forehead. Most also have tufts of long hair around or from the ears, although the silvery marmoset (Callithrix argentata) has bare ears.

These small primates are active in the daytime. They sleep in tree holes or tangles of vines during the night. Tamarins and marmosets live in groups of up to 40 individuals, though 12-15 is more usual. They spend a great deal of time grooming each other. Their social groups can create a great amount of noise and commotion.

After a 140-145 day gestation period, a female (usually only one in a group at a time) produces two young (or sometimes one or three). The newborn babies are relatively large in comparison to those of other monkeys, although they are helpless. They ride on the back of a parent (usually the father) until they are about 7 weeks old. They become sexually mature at 12-18 months. The young are allowed to stay around the family even after they have reached sexual maturity, and after a new family is born to the parents. However, they do not produce their own offspring until after they leave the family unit. The young animals help their parents, often relieving the male in carrying his newer offspring. Otherwise, the male turns the young over to the female for short feeding periods every few hours.

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