robusticity was measured as detailed in Latimer and Lovejoy18 and modified slightly in Zipfel et al.5. There is plantar damage to UW 101–1322 and the minimum area of the calcaneal tuber was estimated from a digital cross-section (using DeskArtes) of a surface scan of the original fossil. Tuber volume was then calculated as the product of the mimimum cross-sectional area of the tuber times the length of the tuber (from the midpoint of the proximal talar facet to the most proximal point of the calcaneal tuber). Calcaneal robusticity was calculated as the tuber volume divided by body mass. Body mass for the Foot 1 individual was calculated from regression-based equations of McHenry33 based on the talar trochlea width of the associated talus UW 101–1417. Comparative values were generated from data provided in Latimer and Lovejoy18 on modern apes and humans, with modified body masses in the apes from Smith and Jungers34. Data on calcaneal robusticity in Au. afarensis were from Latimer and Lovejoy18 and modified with a body mass generated from the regression-based equations of McHenry33 for talar trochlea width of A.L. 333-147—a not necessarily associated talus, but from a similarly sized individual as A.L. 333-8 and A.L. 333-55. Data on A.L. 333-147 are taken from Ward et al.35. Data for Au. sediba are taken from Zipfel et al.5.