Laetoli Footprints

The Laetoli footprints of Tanzania date back to approximately 3.5Ma. There are two sets of parallel prints that pressumably belong to Australopithecus afarensis due to their age. The prints were created when these hominids walked over freshly fallen ash from the Sadiman volcano. Due to its chemical composition, the next rainfall hardened the ash and preserved the footprints (Cowen, 2005). 

There has been much debate as to whether the prints indicate a hominid using a bent-knee, bent-hip biped walking posture like that used by chimpanzees or if they indicate a straight hind limb walking posture like that used by modern humans. Raichlen, Pontzer, and Sockol concluded in their kinesthetic study that either walking posture could have been utilized the by Laetoli hominids to create those particular track patterns (2008).