Adding to an electrifying discovery made almost 40 years ago, researchers have uncovered a new set of footprints made by an early human ancestor that roamed Africa more than 3.6 million years ago.

Found in Laetoli, a renowned archaeological site in northeastern Tanzania, the 14 newfound footprints add to a set of 70 tracks uncovered in 1978 by paleontologist Mary Leakey. In all, the tracks are the oldest prints of their kind ever found, providing crucial evidence that walking on two legs was picked up early in the human lineage.

Spread out over an area three times bigger than an average parking space, the prints most likely belong to two individuals of Australopithecus afarensis, the hominin species most famously represented by the