Evidence that the species Australopitehcus afarensis did walk bipedally came from a spectacular 70-meter (more than 21-foot) trail of footprints fossilized in volcanic ash at Laetoli in Africa.

The fossil footprints were rather whimsically discovered by exhibition curator Andrew Hill when visiting Mary Leakey (seen here at right) in 1976. While walking back to camp one evening, Hill fell trying to avoid a large ball of elephant dung thrown at him by a colleague. With his face only inches from the rock, he recognized footprints made by antelopes and rhinos preserved in the volcanic ash, and among these, hominid footprints.