Figure 8.

The afrotherian cortex is folded differently from that of rodents and primates. (A) folding index of the cerebral cortex (ratio between the total surface area and the exposed surface area of the cortex) plotted as a function of the volume of the cortical gray matter for rodents (green), primates (red), and the two hyraxes (black). Notice that the two hyraxes appear to overlap with primates, but not rodents. (B) folding index of the cerebral cortex plotted as a function of the number of cortical neurons in each species. For similar numbers of cortical neurons, the cortex of the two hyraxes is more folded that the cortex of both primates and rodents. Data from Ventura-Antunes et al. (2013). Eulipotyphla and the smaller Afrotheria are lissencephalic, and data on their cortical surface areas and volumes were not available.