Monkeys have lived in South America for 36 million years, according to a new study published in the journal Nature.
This news comes despite the fact that the creatures likely didn't originate on that continent, but rather evolved in Africa and somehow crossed the Atlantic.
"How and when monkeys arrived in South America remain the major questions," said Ken Campbell, curator at the Natural History Museum of Los Angeles County, which led the study.
Campbell's team were able to determine that monkeys have been in South America millions years longer than previously thought, thanks to four molars discovered in Eastern Peru.
The fossilized teeth were first found in 2010.
They were so unlike anything known to exist in South America that it took two years for researchers to determine they were from a monkey.
The team of was able to estimate they were 36 million years old, which is 10 million years older than any other known South American monkey fossil.
The animal, dubbed Perupithecus ucayaliensis, is believed to have been about the size of a squirrel but with a much longer tail.
Campbell also noted that its teeth also bore a striking resemblance to fossils of ancient African monkeys, giving more credence to the idea that these creatures crossed the Atlantic at some point.
How they did that remains a mystery.
"The primary hypothesis is that they floated on a raft of vegetation, but that is still a big question," Campbell said.
He points out, the journey may have been a little easier 36 million years ago since due to the shifting of the continents, the Atlantic was considerably narrower back then.