<P> The evolutionary history of the primates can be traced back 65 million years . One of the oldest known primate - like mammal species, the Plesiadapis, came from North America; another, Archicebus, came from China . Other similar basal primates were widespread in Eurasia and Africa during the tropical conditions of the Paleocene and Eocene . Purgatorius is the genus of the four extinct species believed to be the earliest example of a primate or a proto - primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 66 million years ago . </P> <P> David Begun concluded that early primates flourished in Eurasia and that a lineage leading to the African apes and humans, including Dryopithecus, migrated south from Europe or Western Asia into Africa . The surviving tropical population of primates, which is seen most completely in the upper Eocene and lowermost Oligocene fossil beds of the Faiyum depression southwest of Cairo, gave rise to all living species--lemurs of Madagascar, lorises of Southeast Asia, galagos or "bush babies" of Africa, and the anthropoids: platyrrhine or New World monkeys, catarrhines or Old World monkeys, and the great apes, which share common ancestors with Homo sapiens . </P>

When did the first primates appear on earth