The evolutionary history of the primates can be traced back 57-90 million years. One of the oldest known primate-like mammal species, Plesiadapis, came from North America; another, Archicebus, came from China. Other such early primates include Altiatlasius and Algeripithecus, which were found in Northern Africa. 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 among 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.