<Tr> <Th_colspan="2"> Families </Th> </Tr> <Tr> <Td_colspan="2"> <Ul> <Li> Callitrichidae </Li> <Li> Cebidae </Li> <Li> Aotidae </Li> <Li> Pitheciidae </Li> <Li> Atelidae </Li> </Ul> </Td> </Tr> <Ul> <Li> Callitrichidae </Li> <Li> Cebidae </Li> <Li> Aotidae </Li> <Li> Pitheciidae </Li> <Li> Atelidae </Li> </Ul> <P> New World monkeys are the five families of primates that are found in the tropical regions of Central and South America and Mexico: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae . The five families are ranked together as the Ceboidea, the only extant superfamily in the parvorder Platyrrhini . Platyrrhini means flat - 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 . </P>

What is the difference between new world monkeys and old world monkeys