Laetoli is a site in Tanzania, dated to the Plio-Pleistocene and famous for its hominin footprints, preserved in volcanic ash. The site of the Laetoli footprints (Site G) is located 45 km south of Olduvai Gorge. The location and tracks were discovered by archaeologist Mary Leakey in 1976, and were excavated by 1978. Based on analysis of the footfall impressions "The Laetoli Footprints" provided convincing evidence for the theory of bipedalism in Pliocene hominins and received significant recognition by scientists and the public. Since 1998, paleontological expeditions have continued under the leadership of Dr. Amandus Kwekason of the National Museum of Tanzania and Dr. Terry Harrison of New York University, leading to the recovery of more than a dozen new hominin finds, as well as a comprehensive reconstruction of the paleoecology.
Dated to 3.7 million years ago, they were the oldest known evidence of hominin bipedalism at that time. Subsequently, older Ardipithecus ramidus fossils were found with features that suggest bipedalism. With the footprints there were other discoveries excavated at Laetoli including hominin and animal skeletal remains. Analysis of the footprints and skeletal structure showed clear evidence that bipedalism preceded enlarged brains in hominins. At a species level, the identity of the hominins who made the trace is obviously difficult to precisely construe; Australopithecus afarensis is the species most commonly proposed.