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.