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Scientists have discovered the oldest monkey fossils – by more than 17 million years – found in North America. The find suggests that, 21 million years ago, a group of monkeys found a way to cross a 100-mile stretch of ocean from South America into present day Panama.

A team of scientists led by Dr. Jonathan Bloch, the curator of vertebrate paleontology at the Florida Museum of Natural History and a professor at the University of Florida, named the pioneering monkey Panamacebus transitus – in honor of the fact the fossils were discovered during the expansion of the Panama Canal.

Bloch told Fox News Latino that the Panamacebus was probably very much like a capuchin crossed with a squirrel monkey – two species that are common to the jungle areas of Central and South America.

“The one we found in Panama is clearly related to ones that are alive today,” Bloch said, “and it came across 21 million years ago.”

Prior to their discovery, scientists believed primates first migrated from South America to North America 3.5 million years ago when the two landmasses connected via Panama. The Panamacebus found a way to cross during the early Miocene Epoch, when the ocean known as the Central American Seaway divided the continents.

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“Everyone understands that this is a strange revelation,” Bloch admits. “It happened, but the question is, How did it happen?”

The leading hypothesis is the monkeys unintentionally sailed to North America on natural rafts or “vegetation mats” – floating islands of earth and plants clumped together that washed out to sea during, say, a violent storm.

Scientists believe this is how primates originally made their way to South America from Africa some 40 million years ago.

“Tropical places of the world are so tough to find fossils in,” Bloch told FNL. “There are a lot of reasons for that, but mainly it’s because the rocks themselves are so tough to find … Imagine our excitement when [the Panama Canal engineers] started cutting through rocks from the early Miocene.”

Another scientist, Carlos Jaramillo of the Smithsonian Tropical Research Institute, described the dig to Science Daily, "I asked my boss for a million dollars to dig a hole in the ground. Then the Panamanian people voted for the Panama Canal Authority to spend $5.6 billion dollars to expand the Canal and unlocked a treasure trove for us, containing this new monkey species."

After the steep canal banks were dynamited, scientists rushed to catalog and collect any exposed fossils before tropical storms could wash them away or the quickly-growing vegetation obscure them. Little did they realize they would find was a South American simian.

“The original observations of fossils in Panama in the 1960s found that all of the animals look like they come from the Great Plains or the Gulf Coast [of North America],” Bloch said. “Camels, horses and rhinos.”

“What you distinctly did not find were the mammals of South America,” he said, until 3.5 million years ago, when the land masses joined up and interchange of species occurred.

Panamacebus didn’t spread very far north, Bloch believes. “They might have gone into Costa Rica but probably not much further,” he said. “The monkeys evolved in places with tropical forests and fruits – that was the kind of thing they liked to eat – and then they hit forests dominated by pines and acorns.”

Bloch told FNL, "We always thought that the Central American Seaway was the major barrier” that prevented monkeys and other South American mammals from extending north before the Americas joined. “But it may be that the water wasn’t the issue – it was the habitat.”