20 April 2015 Telegraph
Ages before the North and South American continents joined together, monkeys related to today’s capuchins were able to accomplish crossing at least 100 miles of open ocean approximately 21 million years ago.
Scientists said on Wednesday they reached that conclusion based on the discovery of seven little teeth during excavations involving the Panama Canal’s expansion, showing monkeys had reached the North American continent far earlier than previously known.
The teeth belonged to Panamacebus transitus, a previously unknown medium-sized monkey species. South America at the time was secluded from other continents, with a strange array of mammals evolving in what 20th century American paleontologist George Gaylord Simpson called “splendid isolation”.
How Panamacebus performed the feat is a bit mysterious. After all, seagoing simians seem somewhat suspicious.
“Panama represents the southernmost extreme of the North American continent at that time,” said Jonathan Bloch, a vertebrate paleontology curator at the Florida Museum of Natural History on the University of Florida campus.
“It may have swum across, but this would have required covering a distance of more than 100 miles, a difficult feat for sure. It’s more likely that it unintentionally rafted across on mats of vegetation,” Bloch added.
Bloch said as far as anyone knows these monkeys were the only mammals that managed to cross the seaway from South America to reach present-day Panama. While South American giant ground sloths managed to reach North America about 9 million years ago, it was not until about 3.5 million years ago that the Isthmus of Panama formed, allowing animals to begin trekking in large numbers between the continents in one of the biggest mixing of species on record.
Bloch said learning that monkeys lived then in North America was a “mind-bending discovery” because it had long been accepted that they simply did not exist there at that time.