40mya Platyrrhini

MARMOSETS, TAMARINS, CAPUCHINS, SQUIRREL MONKEYS, NIGHT MONKEYS, TITI, SAKI, UAKARIS, WOOLY, SPIDER AND HOWLER MONKEYS.

New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America.

Platyrrhini means broad-nosed, and their noses are flatter than those of other simians, with sideways-facing nostrils. Monkeys in the family Atelidae, such as the spider monkey, are the only primates to have prehensile tails.

New World monkeys' closest relatives are the other simians, the Catarrhini ("down-nosed"), comprising Old World monkeys and apes. New World monkeys descend from African simians that colonized South America, a line that split off about 40 million years ago.

While our remote vertebrate ancestors possessed trichromatic vision, our nocturnal, warm-blooded, mammalian ancestors lost one of three cones in the retina at the time of dinosaurs. This is why fish, reptiles and birds are trichromatic while all mammals with the exception of apes and New World monkeys are strictly handicapped dichromats. Because color vision is of paramount importance to diurnal animals that eat ripe fruits, apes and New World monkeys regained tri-color vision independently via chromosomal translocation. In apes, trichromacy resulted from true duplication of the opsin gene.