Two primate lineages crossed the Atlantic millions of years ago

Four fossilized molar teeth excavated in Peru’s Amazon basin come from a now-extinct lineage of primates that rafted across the Atlantic Ocean from Africa and reached the inland site between around 35 million and 32 million years ago, researchers say.

Until now, South American sites had yielded only fossils of primates ancestral to those inhabiting the continent today. Fossils from the same Peruvian site had previously suggested that ancestors of modern South American monkeys crossed the ocean from Africa by around 36 million years ago (SN: 2/4/15). The new discovery adds a second group of primate arrivals.

The teeth closely resemble those of parapithecids, a primate family that inhabited northern Africa from roughly 56 million to 23 million years ago, say paleontologist Erik Seiffert of the University of Southern California in Los Angeles and his colleagues. Like ancestors of living South American monkeys, parapithecids must have made a sea crossing on vegetation mats created by storms, the scientists conclude in the April 10 Science.

Favorable ocean currents and a narrower Atlantic Ocean than today because of lower sea levels helped ancient primates float across the ocean. Still, the Atlantic probably was more than 1,500 to 2,000 kilometers wide when crossings occurred, the scientists say.

The two primate lines adjusted well to a new continent, traveling from where they landed in South America more than 4,000 kilometers to the inland Peruvian site, the researchers say. Seiffert’s group suspects both groups competed for resources until Ucayalipithecus, the genus name given to the newly reported fossils, eventually died out.