Figure 1. A in Enamel microstructure evolution in anthracotheres (Mammalia, Cetartiodactyla) and new insights on hippopotamoid phylogeny

Figure 1. A, schema of a sliced tooth portion showing the vertical (V), horizontal (H), and tangential (T) section planes in the transverse configuration of Hunter–Schreger bands (HSB); EDJ, enamel–dentine junction; OES, outer enamel surface. B, schema of a sliced tooth portion showing the vertical, horizontal, and tangential section planes in the 'slanted' HSB configuration. C, Kenyapotamus coryndonae, vertical section (SEM) of upper molar showing HSBs. D, Kenyapotamus coryndonae, horizontal section (SEM) of upper molar showing only radial enamel with synchronous prism undulation. E, Kenyapotamus coryndonae, tangential section (SEM) of upper molar showing no clearly defined HSBs, with the vertical section plane visible (white dotted line). F, Kenyapotamus coryndonae, tangential section (optical stereomicroscope) of upper molar showing HSBs perpendicular to the vertical section plane (white dotted line) and parallel with the horizontal section plane (black dotted line). G, Microbunodon minimum, vertical section (SEM) showing HSBs. H, Microbunodon minimum, horizontal section (SEM), also showing HSBs. I, Microbunodon minimum, tangential section (SEM) showing 'slanted' HSBs, which are inclined to the vertical section plane (black dotted line) rather than perpendicular.