A primate is a mammal that belongs to the order Primates.
Included in this order are prosimians, monkeys (Old World and New World), and apes,
the latter group including hominids. There
are approximately 350 extant species of primate.
Primates are characterized by:
Primates are by and large an arboreal order whose members usually climb
by grasping. The skull has a bar, which makes
a posterior or lateral margin of the orbit. The shortened face is accompanied
by a diminished sense of smell. However, tree-life
has led to the development of excellent eyesight, typically with binocular
- relatively large brain-to-body mass ratio
- advanced stereoscopic color vision with large, forward-facing eyes
- distinctive eye orbit structure
- five fingers on each hand, with sensitive pads
- nails instead of claws
- aposable thumbs
- specialization of the hands (and sometimes feet) for grasping
- hind limb dominated locomotion
- generalized dental pattern
- unspecialized body plan
- neoteny and a long rearing period for offspring
The first primates appeared at the beginning of the Eocene (55–36 million years ago). There were two varieties of Eocene primates,
similar to modern lemurs and tarsiers. The first apes appeared in the Oligocene (c. 27 million years ago) and the first hominids
(human-like) primates 5 to 4 million years ago.