---
title: "Ancient African monkeys crossed the Atlantic on vegetation rafts, four fossil teeth from Peru show"
url: https://badiyaa.com/ucayalipithecus-monkeys-crossed-atlantic-rafts-peru-teeth/
published: 2026-11-08T07:42:00+00:00
modified: 2026-11-08T07:42:00+00:00
section: Science
publisher: Badiyaa
---

# Ancient African monkeys crossed the Atlantic on vegetation rafts, four fossil teeth from Peru show

Ucayalipithecus perdita, a marmoset-sized primate, reached South America over 30 million years ago, a separate voyage from the ancestors of today's American monkeys.

Four fossil teeth dug out of the Peruvian Amazon show that a family of tiny African monkeys crossed the Atlantic Ocean more than 30 million years ago, most likely on floating rafts of vegetation torn loose from the coast. The species, named Ucayalipithecus perdita, was about the size of a modern marmoset.

The idea that monkeys “sailed” from Africa to the Americas is trending again this weekend, and people are asking whether it can possibly be true. The teeth are the evidence, and the researchers who described them freely call the journey improbable.

## What the teeth show

The molars come from a site called Santa Rosa, on the Río Yurúa in Peru’s Ucayali region. Two of them were first picked out of earlier field finds; when anatomist Erik Seiffert of the Keck School of Medicine of USC examined them in 2016, he saw that they matched an extinct group of primates called parapithecids, previously known only from Africa and Arabia. A trip back to Santa Rosa that year turned up two more teeth.

The team’s analysis put the Peruvian monkey closest to Qatrania wingi, a parapithecid from Egypt. “This is a completely unique discovery,” Seiffert said in USC’s announcement of the study, published in the journal Science in April 2020.

Its name is a small story of its own: Ucayali for the region, pithikos for the Greek word for monkey, and perdita, Latin for lost.

## A third set of castaways

Here is the context that makes the find matter. South America was an island continent at the time, so any mammal arriving from Africa had to cross open sea. Two groups were already known to have done it: the ancestors of today’s New World monkeys, and the caviomorph rodents, the family that includes guinea pigs. Ucayalipithecus is a third lineage, and a separate one. It is not an ancestor of any living American monkey; its family later died out.

## The crossing, by the numbers

- **Distance:** USC put the trip at more than 900 miles. The Atlantic in that region was still more than 1,500 kilometers wide, roughly 930 miles.

- **Timing:** the team estimated the lineage split from its African relatives about 35.1 million years ago and reached South America by about 31.7 million years ago.

- **Weight:** estimates from one molar put the animal at roughly 319 to 366 grams, about 11 to 13 ounces.

The timing lines up with a helpful accident of climate. Around the boundary between the Eocene and Oligocene epochs, Antarctica’s ice sheet began to grow and sea levels fell. “That might have played a role in making it a bit easier for these primates to actually get across the Atlantic Ocean,” Seiffert said.

## What is still unknown

Nobody can say exactly how long the voyage took, what route the rafts followed, or how many animals made it. The fossils show where the monkeys ended up, not the journey itself. Dating is also debated: a 2021 study of zircon crystals at Santa Rosa gave the sediments a maximum age of about 29.6 million years, younger than some earlier estimates, though still within the Oligocene.

Seiffert summed up the odds himself: “The thing that strikes me about this study more than any other I’ve been involved in is just how improbable all of it is.” The four teeth, catalogued in Lima under numbers beginning CPI-79, are the whole record of the species so far.

## Further reading

- [Wikipedia: Ucayalipithecus](https://en.wikipedia.org/wiki/Ucayalipithecus)

*Image: NASA Johnson Space Center, Public domain via Wikimedia Commons*

*This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*