Trail of hominid footprints fossilised in volcanic ash. This 70 metre trail was found by Mary Leakey's expedition at Laetoli, Tanzania in 1978. It dates from 3.6 million years and shows that hominids had acquired the upright, bipedal, free- striding gait of modern man by this date. The trail probably belongs to Australopithecus afarensis and dates from 3.7 to 3 million years ago. The footprints show a well developed arch to the foot and no divergence of the big toe. They are of two adults with possibly a third set belonging to a child who walked in the footsteps of one of the adults. The prints to the far right belong to an hipparion, an extinct three-toed horse.