Fig. 3: Box and whisker plots showing the distribution of δ^44/42Ca values (in ‰) between Turkana Basin Paranthropus boisei, South African Paranthropus robustus³³ and associated mammal faunas.

Data for grazers, browsers, and carnivores are from Martin et al.²⁹ and Tacail et al.³³. EA East Africa, SA South Africa. Values selected for representatives of the associated-fauna include only those values for organisms circa 2 Ma; for this reason, the browser category may appear underrepresented and the apparent difference may reflect specific dietary differences rather than differences in the substrate isotope baseline. Note that carnivore values in EA are dispersed as explained by a dataset that includes sabertooth felids. The boxes represent the first and third quartiles with the medians as horizontal lines. The lower and upper whiskers represent 1.5 * the interquartile range (numbers of biologically independent samples per group: n = 7 for South African carnivores; n = 10 for East African carnivores; n = 7 for South African browsers; n = 4 for East African browsers; n = 10 for South African grazers; n = 14 for East African grazers; n = 38 for Paranthropus robustus; n = 8 for Paranthropus boisei). δ^44/42Ca values are expressed both against ICP Ca Lyon (left) and SRM915a (right). Source data are provided as a Source Data file.