|Catalog number||Stw 573|
|Common name||Little Foot|
|Species||Australopithecus, species uncertain|
|Place discovered||South Africa|
|Discovered by||Ronald J. Clarke|
In 1994 while searching through museum boxes labelled 'Cercopithecoids' containing fossil fragments, paleoanthropologist Ronald J. Clarke identified several that were unmistakably hominin. He spotted four left foot bones (the talus, navicular, medial cuneiform and first metatarsal) that were most likely from the same individual. These fragments came from the Silberberg Grotto, a large cavern within the Sterkfontein cave system. They were described as belonging to the genus Australopithecus, and catalogued as Stw 573.
Due to the diminutive nature of the bones, they were dubbed "Little Foot". Dr. Clarke found further foot bones from the same individual in separate bags in 1997, including a right fragment of the distal tibia that had been clearly sheared off from the rest of the bone. Two fossil preparators and assistants of Dr. Clarke, Stephen Motsumi and Nkwane Molefe, were sent to the Silberberg Grotto to try to find the matching piece of tibia that attached to this fragment. Amazingly, within two days they found the remaining part of the bone protruding from the rock in the lower part of the grotto. Careful excavation by Dr. Clarke and his team lead to the uncovering of a complete skull and jaw in articulation, as well as other limb bones.
These were announced to the press in 1998, resulting in considerable media attention around the world.
Subsequent work has uncovered a relatively complete skeleton, including a complete forearm and hand in articulation, parts of the pelvis, ribs and vertebrae, a complete humerus and most of the lower limb bones. This sensational discovery is still being excavated and is likely to be far more complete than the famous Australopithecus afarensis skeleton, "Lucy", from the site of Hadar, Ethiopia.
Clarke now suggests that Little Foot does not belong to the species Australopithecus afarensis or Australopithecus africanus, but to a unique Australopithecus species previously found at Makapansgat and Sterkfontein Member Four, Australopithecus prometheus.
The complex geology of Sterkfontein makes precise dating of Stw 573 difficult. There are no volcanic tuffs to ensure accurate radiometric dating, and the paleomagnetic sequences are incomplete. Further to this, there has been considerable debate in the scientific literature as to how old Stw 573 is. Estimates range from almost 4 Ma based on cosmogenic 26Al and 10Be radiometric dating  to 2.2 Ma  based on uranium-lead dating. A magnetochronology estimate places the fossil at about 3.3 Ma.
- Clarke, R.J. and P.V. Tobias (1995). Sterkfontein Member 2 foot bones of the oldest South African hominid. Science 269, 521–524.
- Clarke, R.J. (1998). First ever discovery of a well-preserved skull and associated skeleton of an Australopithecus. South African Journal of Science, 94; 460–463.
- Clarke, R.J., (2008) "Latest information on Sterkfontein's Australopithecus skeleton and a new look at Australopithecus"; South African Journal of Science, Vol 104, Issue 11 & 12, Nov / Dec, 2008, 443–449. See also "Who was Little Foot?" The Witness, 20 March 2009.
- Bower, Bruce, (2013) "Notorious Bones"; Science News, August 10, 2013, Vol. 184, No. 3, p. 26.
- Partridge, T.C., Granger, D.E., Caffee, M.W. and Clarke, R.J. (2003) - « Lower Pliocene Hominid Remains from Sterkfontein », Science, Vol. 300, pp. pp. 607–612. (abstract)
- Walker, J., Cliff, R.A. and Latham, A.G. (2006) - « U-Pb Isotopic Age of the StW 573 Hominid from Sterkfontein, South Africa », Science, Vol. 314, pp. pp. 1592–1594. (abstract)
- Partridge, T.C., Shaw, J., Heslop, D. and Clarke, R.J. (1999) - « The new hominid skeleton from Sterkfontein, South Africa: age and preliminary assessment », Journal of Quaternary Science, 14, pp. 293–298.