Origin
About 40 million years ago the Simiiformes infraorder split into parvorders Platyrrhini (New World monkeys—in South America) and Catarrhini (apes and Old World monkeys—in Africa). The individuals whose descendents would become Platyrrhini are currently conjectured to have migrated to South America either on a raft of vegetation or via a land bridge. There are two possible rafting routes, either across the Atlantic Ocean from Africa or across the Caribbean from North America. However, there is no fossil record to support the hypothesis of a migration from North America. The land bridge hypothesis relies on the existence of Atlantic Ocean ridges and a fall in the sea level in the Oligocene. This would have either produced a single land bridge or a series of mid-Atlantic islands to act as stepping stones for the migration.
At that time, the Isthmus of Panama had not yet formed, ocean currents and climate were quite different, and the Atlantic Ocean was less than the present 2,800 km (1,700 mi) width by about a third; possibly 1,000 km less, based on the current estimate of the Atlantic mid-ocean ridge formation processes spreading rate of 25 mm/year.
Read more about this topic: New World Monkey
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