The term that refers to a tail that can be used to grasp objects and even support the body like a hand. Some of the New World monkeys have tails with these capabilities, but none of the Old World primates have them.

The family of New World monkeys that includes the marmosets and tamarins. They are the smallest of all monkeys. They are also considered to be the most primitive monkeys in that their thumbs are not opposable, they have claws on all digits except for their big toes, they lack the ability to change their facial expressions, and twin births are common for them. They do not have prehensile tails.

The family of New World primates that include squirrel, howler, spider, capuchin, and many other monkey species. Some of them are as large as medium-sized dogs, but most are smaller. Like the Old World monkeys, they have nails on all of their fingers and toes. Some members of this family have prehensile tails.

A skin surface that is sensitive to pressure, temperature, and pain because there are high concentrations of nerve endings immediately below these areas. The pad of skin with finger prints at the tip of your fingers is an example.

The term referring to anatomical differences between males and females of the same species. For example, non-human Primate males are usually significantly larger and stronger than females.

The term referring to a stomach with "saccules," or sack-like compartments, in which bacteria slowly break down cellulose in vegetable foods, such as tough leaves, thereby providing more useable calories. Among the primates, the colobus, langurs, and proboscis monkeys have this characteristic. Cows and related animals also have it.

The term for cheeks that are so elastic that they can expand to allow temporary storage of food. Some of the Old World monkeys have this characteristic as do hamsters and some other rodents.

The subfamily of Old World monkeys that includes the baboons, mangabeys, mandrills, guenons, patas monkeys, and macaques. These are all African species with the exception of the macaques which also live in Asia and Gibraltar. Many of these species sleep in trees or on cliff faces and spend their days in large groups foraging for food on grasslands. Many of them also have ischial callosities, cheek pouches, and sexual skins. They are omnivorous.

The subfamily of Old World monkeys that include the colobus of Africa and the South Asian langurs and proboscis monkeys. All of them are herbivores. They lack cheek pouches. They also share in common the fact that they have sacculated stomachs and unusually long intestines that increase the absorption of nutrients. These are all adaptations to a predominantly low protein, fibrous leaf diet. Not surprisingly, they are also referred to as the "leaf-eating monkeys."

A species in the family Cebidae. They are the largest New World monkeys. Like the indris of Madagascar, they have developed the unusual habit of defending territory in the branches of their forest canopies with vocalizations. They do this with a specialized larynx and throat that expands like a balloon. Their deep, throaty sound is extraordinarily loud.

A kind of small New World monkey whose favorite food is carbohydrate rich tree sap which they tap by gnawing holes in trunks. Their territories are centered on the trees that they regularly exploit in this way. Some eat flower nectar as well.

The only New World monkey species known to use tools as an aid in getting food. This monkey has the largest brain-to-body size ratio of any primate other than humans.

A kind of South Asian monkey that has a sacculated stomach.

A kind of African monkey that has a sacculated stomach.

A kind of African monkey that has cheek pouches but not a sacculated stomach.

baboon, mangabey, mandrill, guenon, patas monkey, or macaque

The only member of the Cercopithecinae subfamily of Old World monkeys that lives outside of Africa.