A primate 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. Primates are found all over the world. Non-human 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 order Primates was established by Linnaeus in 1758, in the tenth edition of his book Systema Naturae for the genera Homo (humans), Simia (other apes and monkeys), Lemur (prosimians) and Vespertilio (bats). In following editions, he also suggested that non-primate mammals should be called Secundates and that non-mammal animals should be called Tertiates, neither of which was accepted. In the first edition (1735), he had used the taxon Anthropomorpha for Homo, Simia and Bradypus (sloths).
The Latin primas means "one of the first, excellent, noble" (nominative plural primates). The English singular primate was derived via back-formation from the Latin inflected form.
The Primates order is divided informally into three main groupings: prosimians, monkeys of the New World, and monkeys and apes of the Old World. 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.
According to fossil evidence, primitive ancestors of primates already existed in the latest Cretaceous. Molecular clock studies suggest that the primate branch is even more ancient (originating at least in the mid-Cretaceous). They are now thought to be most closely related to flying lemurs and, more distantly, to treeshrews. They probably have descended from Plesiadapiformes.