Updated: May 9, 2017 12:15 PM ET | Originally published: May 9, 2017 11:06 AM EDT

Fossils of Homo naledi — a small-brained ancient relative of the human species discovered in a South Africa cave system two years ago — have revealed that they roamed earth at the same time as the earliest members of the human race, scientists say.

Research published in the journal eLife says that when the skeletons were first discovered, scientists thought they could be as ancient as 2.5 million years old. However, the team is now reporting that the fossils are actually between 236,000 and 335,000 years old — which would mean the species existed at the same time as the earliest humans evolved.

“These new findings demonstrate why it can be unwise to try to predict the age of a fossil based only on its appearance, and emphasize the importance of dating specimens via independent tests,” their report says.

The Homo naledi fossils revealed human-like feet and curved hands with opposable thumbs, much like our own. However, the species’ brain is much smaller than humans’, suggesting the creatures were more primitive.

Write to Kate Samuelson at kate.samuelson@time.com.

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