Archaeologists in the Amazon found four small teeth that had no business being in South America. The teeth are from an extinct species of monkeys from the family of primates known as parapithecids—which once roamed in North Africa. In a new paper in Science, researchers lay out what they say must have happened: The monkeys accidentally crossed the Atlantic on some kind of vegetative raft, perhaps one that was unmoored from the African continent during a violent storm, explains Smithsonian. A few key factors would have helped. For one, this was roughly 30 million years ago, when the continents were much closer together—perhaps about 900 miles instead of today's 1,770 miles. Also, this occurred during what is known as the Late Eocene era, when sea levels were down significantly because of the development of glaciers.
The discovery "reveals that, for the last century or so, we have been missing a whole chapter in the chronicle of primate evolution in South America," says study author Erik Seiffert of USC. Scientists named the monkeys Ucayalipithecus perdita, which translates to "lost monkey of Ucayali," referring to the area in Peru where the teeth were found. The monkeys would have been relatively small, about the size of marmosets, per a news release. Scientists already knew that another group of primates made such an accidental trip from Africa to South America; the new study shows it happened at least twice, and probably around the same time, per the Conversation. The Ucayali monkeys must have been "hardy," the post adds, given that they not only survived the journey, they evidently traveled a long distance inland to establish themselves. (Read more discoveries stories.)