Researchers studying monkey fossils unearthed in Peru have noticed a striking resemblance between their newly discovered, squirrel-sized South American species and primitive African monkeys. The fossilized molars, described in Nature this week, also extend the South American primate fossil record by about 10 million years.
New World monkeys are a group of primates that currently live in Central and South America, but where they come from and when they arrived have always been a mystery. After all, South America was an island continent for millions of years. It’s possible that monkeys, rodents, and such made the long transatlantic journey from Africa, but there’s no fossil evidence to support that idea.
Now, a team led by Kenneth Campbell Jr. from the Natural History Museum of Los Angeles County have discovered three fossil teeth—two incomplete upper molars and one complete lower molar—in the Peruvian Amazon during the course of multiple trips beginning in 2010. “Fossils are scarce and limited to only a few exposed banks along rivers during the dry seasons,” Campbell explains in a news release. “For much of the year high water levels make paleontological exploration impossible.”
Until now, the oldest fossils of New World monkeys—which were uncovered in Salla, Bolivia—date back 26 million years, in the late Oligocene. These new fossil teeth are 10 million years older, dating back to the late Eocene epoch and making them the oldest fossil record of New World monkeys known. That also means monkeys first arrived in South America at least 36 million years ago.
The team named this new small, extinct primate Perupithecus ucayaliensis. The genus name combines Peru with “pithecus,” which is Greek for monkey, and the species name refers to the Ucayali Department of Santa Rosa where it was found.
According to their analyses, these three new extinct monkeys don’t really resemble any South American primate, living or extinct. However, the teeth of Perupithecus bear a striking resemblance to Eocene African primates, suggesting that monkeys did actually manage to cross the Atlantic Ocean from Africa.