CHICAGO - MARCH 07:  "Lucy," an Australopithecus afarensis, is displayed as part of the "Evolving Pl...

Bipedalism, baby

Look: 3.6-million-year-old prints likely belong to an undiscovered ancient human

A. afarensis didn’t roam alone.

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In the late 1970s, paleoanthropologists digging in modern-day Tanzania discovered something remarkable.

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They unearthed a series of fossilized footprints made 3.6 million years ago and preserved in volcanic ash.