Fossilized teeth show that two different kinds of ancient human ancestors coexisted more than 2 million years ago. One of them may be an unknown species.

In the dry, rugged badlands of Ethiopia’s Afar Region, a team of scientists has uncovered fossils that could change how you picture human evolution. These finds, dating back between 2.6 and 2.8 million years,

Researchers have unearthed tooth fossils in Ethiopia dating to about 2.65 million years ago of a previously unknown species in the human evolutionary lineage, one that lived in the same time and place as the earliest-known member of the genus Homo to which our own species belongs.