The primates that made the journey in this story were small, about the size of a squirrel. They did not construct their own rafts of course, but rather the very ground beneath their feet would have been swept away, leaving them stranded on a floating island. Let’s picture a scene here of maybe 100 monkeys hanging out near the western coast of Africa. Suddenly, ᴅɪsᴀsᴛᴇʀ strikes.
“I would assume that those rafts were pretty dramatic events,” said Alexandre Antonelli, Professor in Systematics and Biodiversity at the University of Gothenburg in Sweden. “It could have been a ᴛsᴜɴᴀᴍɪ or a really big sᴛᴏʀᴍ. So I don’t think they were having a good time on the island. But it probably was pretty fast and dramatic.” “We don’t know for sure what the raft looked like, but it was probably some sort of mat of vegetation.”
Some theories suggest that these mats could even support trees. If that’s the case, they could act as sails, carrying the island at speeds above that of just the ocean current, reducing the time any animals aboard would need to survive.
Floating rafts like these are not unprecedented. Years ago, we spotted one in the Atlantic that measured about 840 square meters (9,000 square feet) in size. It was seen in two places 1,600 kilometers (1,000 miles) apart, meaning it had survived a pretty long time. This is not even the biggest raft that has been found.
“It’s the dirt and the roots that are holding it together, and then the vegetation on top,” said de Queiroz. “So it makes this pretty substantial island, and it’s not just vegetation.”
Alain Houle, from the University of Montreal, calculated how long it would take to cross the Atlantic Ocean under these conditions. He suggested the journey from Africa to South America may have been as short as 14.7 days, with a similar amount of time for the subsequent journey to North America 20 million years later. The quicker the better in terms of survival.
But the monkeys also probably benefited from being omnivorous, being able to eat pretty much anything they could find on the raft. “Assuming some fresh water could be found in the leaves, roots, insects, fruits, bark, and other similar food items, an animal like a paleomonkey could survive those two weeks,” Houle told IFLScience. With enough rain, it’s possible they could have survived for quite some time.
“Even a month or two months, if the raft is big enough and has all kinds of vegetation on it, there could be enough food for a group of monkeys to actually survive,” added de Queiroz. “Maybe they wouldn’t even be that stressed.”
Once they arrived in the Americas, it looks like they took to their surroundings pretty quickly. With a similar climate and abundant food, they spread far and wide. For some reason, though, the descendants of these sailing monkeys did not venture further into North America after their second voyage.
“Once the monkeys crossed the [Central American Seaway], they found a rainforest just like the one they left and the fruits they were used to eating,” said Bloch. But if they’d headed north, they would have started to find the available food changing to things like acorns, which were not in their diet, and thus stopping them going much further.