Monkeys resembling today’s capuchins crossed at least 160 kilometres of open ocean 21 million years ago to get from South America to North America, eons before the two continents joined together.
Scientists reached that conclusion based on the discovery of seven teeth during excavations related to the Panama Canal. It showed that monkeys had reached the North American continent far earlier than believed.
The teeth were from Panamacebus transitus, a medium-sized monkey. South America at the time was secluded from other continents, with its mammals evolving in what 20th-century palaeontologist George Gaylord Simpson called “splendid isolation”.
How Panamacebus performed the feat was a bit of a mystery. “Panama represents the southernmost extreme of the North American continent at that time,” said Jonathan Bloch, a vertebrate palaeontology curator at the Florida Museum of Natural History.
“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.”
While South American giant ground sloths managed to reach North America about nine 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.
Mr Bloch said learning that monkeys lived in North America then was a “mind-bending discovery” because it had long been accepted that they did not exist there at that time.
It would be akin to learning that Australia’s kangaroos and koalas live in the wilds of Asia today.
Monkeys originated in Africa and later spread. Scientists believed monkeys made an even longer transoceanic voyage, perhaps 37 million years ago, when they crossed from Africa to South America, also probably on floating debris.
Mr Bloch said the seven teeth, the largest of which were molars about 5mm long, were unmistakable as belonging to a South American monkey, and their shape showed Panamacebus had a diet of fruit in its tropical forest environment.
The research was published in the journal Nature.
* Reuters