U-Pb isotopic age of the StW 573 hominid from Sterkfontein, South Africa

Sterkfontein cave, South Africa, has yielded an australopith skeleton, StW 573, whose completeness has excited great interest in paleoanthropology. StW 573, or Little Foot, was found 25 meters below the surface in the Silberberg Grotto. U-238-Pb-206 measurements on speleothems immediately above and below the fossil remains, corrected for initial U-234 disequilibrium, yield ages of 2.17 +/- 0.17 million years ago (Ma) and 2.24(-0.07)(+0.09) Ma, respectively, indicating an age for StW 573 of close to 2.2 Ma. This age is in contrast to an age of similar to 3.3 Ma suggested by magnetochronology and ages of similar to 4 Ma based on Be-10 and Al-26, but it is compatible with a faunal age range of 4 to 2 Ma.