Laetoli is the name of an archaeological site in Tanzania, where by some very odd twist of fate, the footprints of three Australopithecines have have been preserved some 3.6 million years.
The two 27.5 meter long trails of footprints were created in moist volcanic ash which later hardened because of desiccation and chemical change. Three hominin individuals are represented, called G1, G2, and G3. G1, represented by 38 footprints, was a short individual, 1.22 meter or less in height. Individuals G2 and G3 were larger, G3 following almost but not quite, in the 31 footprints of G2. The footprints were discovered in the late 1970s by Mary Leakey, and they are believed to represent Australopithecus afarensis.
The footprints have been definitely linked to A. afarensis, because, like the fossils of afarensis, the Laetoli footprints do not indicate an opposable great toe. Many researchers believe that the Laetoli footprints prove that our Australopithecine ancestors were bipedal, and walked in a modern manner, heel first, then toe. However, a recent study suggests that the speed at which the footprints were made might effect the kind of gait required to make the marks.
Sources
Feibel, Craig S., et al. 1995-1996 The Laetoli Hominid footprints--A preliminary report on the conservation and scientific restudy. Evolutionary Anthropology 4(5):149-154.
Leakey, M. D. and R. L. Hay. 1979. Pliocene footprints in the Laetolil Beds at Laetoli, northern Tanzania. Nature 278:317-323.
Raichlen, David A., Herman Pontzer, and Michael D. Sockol. in press. The Laetoli footprints and early hominin locomotor kinematics. Journal of Human Evolution in press.
Tuttle, R. H., D. M. Webb, and M. Baksh 1991 Laetoli toes and Australopithicus afarensis. Human Evolution 6(3):193-200.
