Primates

A primate (L. prima, first) is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the latter category including humans. The English singular primate is a back-formation from the Latin name Primates, which itself was the plural of the Latin primas ("one of the first, excellent, noble"). Discounting human habitation, primates occur mostly in Central and South America, Africa, and southern Asia. A few species exist as far north in the Americas as southern Mexico, and as far north in Asia as northern Japan.

The Primates are divided into three main groupings. The prosimians are species whose bodies most closely resemble that of the early proto-primates. The most well known of the prosimians, the lemurs, are located on the island of Madagascar and to a lesser extent on the Comoros Islands, isolated from the rest of the world. The New World monkeys include the familiar capuchin, howler, and squirrel monkeys. They live exclusively in the Americas. Discounting humans, the rest of the simians, the Old World monkeys and the apes, inhabit Africa and southern and central Asia, although fossil evidence shows many species existed in Europe as well

All primates have five fingers (pentadactyly), a generalized dental pattern, and a primitive (unspecialized) body plan. Another distinguishing feature of primates is fingernails. Opposing thumbs are also a characteristic primate feature, but are not limited to this order; opossums, for example, also have opposing thumbs. In primates, the combination of opposing thumbs, short fingernails (rather than claws) and long, inward-closing fingers is a relic of the ancestral practice of brachiating through trees. Forward-facing color binocular vision was also useful for the brachiating ancestors of humans, particularly for finding and collecting food, although recent studies suggest it was more useful in courtship. All primates, even those that lack the features typical of other primates (like lorises), share eye orbit characteristics, such as a postorbital bar, that distinguish them from other taxonomic orders.[citation needed]Old World species tend to have significant sexual dimorphism. This is characterized most in size difference, with males being upto a bit more than twice as heavy as females. This dimorphism is a result of a polygynous mating system where there is significant pressure to attract and defend multiple mates. New World species form pair bonds, and so these species (including tamarins and marmosets) generally do not show a significant size difference between the sexes.

Primates evolved from arboreal animals and many modern species live mostly in trees and hardly ever come to the ground. Other species are partially terrestrial, such as baboons and the Patas Monkey. Only a few species are fully terrestrial, such as the Gelada and Humans. Primates live in a diverse number of forested habitats, including rain forests, mangrove forests, and mountain forests to altitudes of over 3000 m. Although most species are generally shy of water, a few are fine swimmers and are comfortable in swamps and watery areas, including the Proboscis Monkey, De Brazza's Monkey and Allen's Swamp Monkey, which even developed small webbing between its fingers. Some primates, such the Rhesus Macaque and the Hanuman Langur, are hemerophile species and cities and villages have become their typical habitat.

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