Fig. 4.

Log–log plot of endocranial volume against body mass for extant primates. Least-squares linear regressions were calculated for haplorhines, open circles (log₁₀ECV = 0.737 × log₁₀BM + 1.305; r² = 0.953) and strepsirhines, triangles (log₁₀ECV = 0.594 × log₁₀BM + 1.090; r² = 0.948). Hadropithecus is indicated by the black star; Archaeolemur species are represented by gray diamonds; thin lines represent 95% confidence intervals. In view of these extremely high correlation coefficients, model II regressions would differ very little from the least-squares lines.