Measurements recorded.

Upper incisors of Rhabdomys pumilio with the measurements marked. Images were produced by the Keyence VHX-2000E digital microscope used in the study. Abbreviations: BD, buccolingual diameter; DE, distal enamel extent; MD, mesiodistal diameter; OD, buccolingual occlusal diameter; RC, outer radius of curvature; OA, occlusal angle. CL, chord length, was used by Croft et al. [28] but was unable to be measured on our fossil specimens (see text for explanation).