Figure 4.

Box plot of EQs, based on Eisenberg's equation [4], of Eocene, Oligocene, Miocene and modern terrestrial artiodactyls, as calculated from intracranial volume. The range of estimates for D. ilicis reflects the array of body mass estimates (see the electronic supplementary material, table S5). Overlain brackets and lines indicate significant pairwise differences in the EQ values. **p < 0.05. See the electronic supplementary material for EQ calculation, corresponding body mass estimates (tables S4–S7) and statistic tests (table S8).