The newly discovered fossilized remains of a monkey found in North America has caught scientists off guard, and can possibly rewrite history books.

Researchers capitalized the planned expansion of the Panama Canal to search for fossils buried beneath the earth. This lifetime opportunity didn't disappoint the researchers. They have uncovered quite a haul of fossilized remains, but the one that took center stage is the discovery of seven monkey teeth that were enclosed in a 21 million-year-old rock.

This discovery, published in the journal Nature, surprised the researchers because the excavated fossil was significantly older than any monkey teeth in Central America should be. The oldest monkeys in the Central Americas were presumed to be 5 million years old.

The discovery is considered to be the earliest evidence of mammalian travel from South America to North America, and now represents the oldest known ancestors of today's New World monkeys. But researchers are bothered by the mystery surrounding how they got there and why they did not continue their journey northward. South America is known to have been an isolated island continent during that time, with seaways at least 160 kilometers wide separating it from North America, Science reported.

Researchers suggest that the early monkey used matted dirt and vegetation as a raft to travel across the sea. They also theorize that these monkeys found South American-like forest structures in Panama and Costa Rica, then opted to stay there rather than continuing north.

In the past, some scientists have suggested that Panama collided with South America millions of years earlier than they have originally thought. This collision could have created a land bridge that the animals could use for cross-continental travel. But researchers of this study noted that the discovery of monkey fossils does not provide enough evidence to back up this claim. If a land bridge was used by animals to cross continents, there should be fossils of larger mammals, but none have yet to be found.

According to the press release of the National Science Foundation, the discovery of the monkey fossil can greatly help researchers to better understand how different plants and animals respond to the changes that occurred in the planet in order to accurately predict actions that should be taken as a response to our ever changing planet in the future.