Hominid footprints. 3D optical laser scan of hominid footprints fossilised in volcanic ash. This is part of a trail found by Mary Leakey's expedition at Laetoli, Tanzania in 1976. It dates from 3.6 million years ago and shows that hominids (probably Australopithecus afarensis) had acquired the upright, bipedal, free-striding gait of modern humans by this time. The footprints show a well developed arch to the foot and no divergence of the big toe. The prints are from two adults, and possibly a third set belonging to a child who walked in the footsteps of one of the adults.