Primate



A primate is a mammal of the order Primates. The primate order includes Terran Humans. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment. Most primate species remain at least partly arboreal.

Characterization
Primates are characterized by large brains relative to other mammals, as well as an increased reliance on stereoscopic vision at the expense of smell, the dominant sensory system in most mammals. These features are more developed in monkeys and apes and noticeably less so in lorises and lemurs. Three-color vision has developed in some primates. Most also have opposable thumbs and some have prehensile tails. Many species are sexually dimorphic; differences include body mass, canine tooth size, and coloration. Primates have slower rates of development than other similarly sized mammals and reach maturity later, but have longer lifespans. Depending on the species, (other than humans), adults may live in solitude, in mated pairs, or in groups of up to hundreds of members.

Origin, Habitat and Size
With the exception of humans, which inhabit every type of habitat, most primates live in tropical or subtropical regions. They range in size from Madame Berthe's mouse lemur, which weighs only 30 g (1 oz), to the eastern lowland gorilla, weighing over 200 kg (440 lb). Based on fossil evidence, the Earth’s earliest known true primates date to 55.8 million years old. Molecular clock studies suggest that the primate branch may be even older, originating in the mid-Cretaceous period around 85 million years ago.