Scientists discovered seven 21-million-year-old monkey teeth fossils that were exposed due to the Panama Canal expansion project and mark the first evidence of a monkey on the North American continent prior to the connection of the Isthmus of Panama to South America 3.5 million years ago.
The team, which includes Carlos Jaramillo, staff scientist at the Smithsonian Tropical Research Institute (STRI), named the new monkey species Panamacebus transitus in honor of Panama and the monkey's journey across the ancient seaway that separated North and South America.
The teeth fossils were discovered in the Las Cascadas Formation during the joint five-year fossil salvage project that was conducted by the STRI, the University of Florida and the New Mexico Museum of Natural History & Science.
Although South America is much closer to the Las Cascadas formation, most mammal groups represented in the area have North American origins, suggesting that Central America and western Panama formed a long peninsula that made its way south from North America.
After the team of engineers dynamited the steep canal banks, researchers collected the exposed fossils that were revealed and made notes of each location before they were covered by heavy rains and fast-growing vegetation. The notes were taken to provide evidence of the tectonic events that raised the land bridge - which eventually connected North and South America - out of the sea.
"I asked my boss for a million dollars to dig a hole in the ground," Jaramillo said. "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 and many other fossils."
"We suggest that Panamacebus was related to the capuchin (also known as "organ-grinder" monkeys) and squirrel monkeys that are found in Central and South America today," said Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History at the University of Florida and lead author on the study. "Prior to this discovery, New World monkeys were thought to have evolved in isolation on South America, cut off from North America by a wide seaway."
Prior to the current findings, the oldest evidence of mammal movement from South to North America resided in 8.5- to 9-million-year-old giant sloth fossils.
The team believes that their findings suggest that either mammals from South America were more adapted to Panama and Costa Rica forests that bore similarities to South American forests, or the lack of exposed fossil deposits in Central America has simply hidden these dispersals.
The findings were published in the April 20 issue of Nature.
