Order Primates—Primates

The Primates, descended from insectivore-like stock, are represented in the New World only by three families (a number of early Tertiary taxa occurred, but eventually became extinct in the Western Hemisphere): the Callithricidae (marmosets) of southern Central America and South America; the Cebidae (New World monkeys) of southern Mexico south to southern Brazil; and the Hominidae (great apes and Homo sapiens, with only the latter native to the New World).

The New World monkeys and the marmosets first appear in the Oligocene and appear to have invaded from Africa, likely by long-distance (sweepstakes) dispersal. Man, on the other hand, is a late arrival, reaching the Western Hemisphere late in the Pleistocene from Asia, along with other mammalian Asiatic invaders.

Many of the features that characterize primates trace to their arboreal background, including stereoscopic vision, grasping hands, and great agility. Anderson's (1967:151) general description is "eutherian mammals having generalized limb structure, primitively arboreal habits, omnivorous diet and comparatively unspecialized teeth; grasping with mobile digits and possessing freely movable limbs; phylogenetically replacing claws with nails and developing enlarged and sensitive pads on digits; reducing nose and sense of smell, enlarging eyes and improving vision, enlarging brain, and progressively improving placentation." Humans have a greatly enlarged cranium (and brain, particularly the cerebral hemispheres) and a greatly reduced rostrum. The foramen magnum is on the ventral surface of the skull, a result of bipedality (Man is the only primate to achieve full bipedal stance), the canines do not extend well beyond the general level of the toothrow, the scapulae are dorsal on the ribcage rather than lateral, and the tooth formula is 2/2, 1/1, 2/2, 3/3 = 32, to mention just some characteristics of the species.

Primates are shown on the Animal Diversity Web.

Last Update: 21 Jan 2008