It may look more like the impression of a jellybean in Play-Doh, or excavations for a kidney-shaped swimming pool, but researchers say the find, at about 15,600 years old, is the oldest human footprint in the Americas — and the latest evidence that people were living throughout the New World much earlier than thought.

According to paleontologists, the single footprint — technically called an ichnofossil, or ichnite — belonged to a human. The impression, preserved in a buried layer of se