The Isthmus of Panama that connects South America with North America formed only about 3.5 million years ago. But latest fossil evidence suggests that monkeys had managed to migrate from the South to North America about 21 million years ago. It means they traveled across 100 miles of water that divided the two continents at the time. Findings of the study were published Wednesday in the journal Nature.

Monkeys Crossed 100 Miles Of Open Sea 21 Million Years Ago

They looked like modern capuchins

Researchers excavated fossils during the Panama Canal expansion project. Panama is the southernmost point of North America. Fossil records suggest that the monkeys would have looked like modern capuchins. Previously, scientists had assumed that New World monkeys evolved in isolation, cut off from the other continent by a wide expanse of sea.

The fossils were recovered by scientists at the Smithsonian Tropical Research Institute, New Mexico Museum of Natural History and Science, and the University of Florida. Researchers named the new monkey species Panamacebus transitus, after the Panama Canal and the monkey’s seafaring ways. The mid-size monkey species was previously unknown.

About 21 million years ago, South America had a strange array of mammals evolving, but it was cut off from other continents. There is very little evidence of animals moving from South America to North America before the Isthmus of Panama emerged 3.5 million years ago. How Panamacebus managed to perform the feat remains a mystery.

Did monkeys swim across 100 miles of water?

Jonathan Bloch, a paleontologist at the Florida Museum of Natural History, said swimming across 100 miles is a difficult feat. It is more likely that the monkeys may have unintentionally rafted across on mats of vegetation. The animals are believed to have made an even lengthier voyage in the past. Monkeys originated in Africa and, about 37 million years ago, traveled from Africa to South America on floating debris.

The discovery suggests that there are more fossils waiting to be discovered in a region. Researchers previously suggested that South American mammals may have preferred the jungles to the south rather than traveling to North America.