Fig 1.
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).
Fig 2.
QDA model predicting modern rodent diets.
The measures OA/MD, OD/DE, BD/MD, and RC/MD were used. Herbivores = red, omnivores = green, seed eaters = blue. Ellipses represent 50% of the distribution of each dietary category. Wilk’s Lambda = 0.345, F = 27.55, p<0.0001.
Table 1.
Predicted vs. actual diets of training specimens used in our QDA model.
Table 2.
Standardized scoring coefficients of QDA model.
Fig 3.
OD/DE (a) and BD/MD (b) of specimens used in the QDA model by dietary category. (a) Seed eaters have thicker enamel caps relative to their occlusal surfaces. Kruskal-Wallis, p<0.0001. Steel-Dwass all pairs comparisons: Herbivore-Omnivore, p = 0.6697; Herbivore-Seed Eater, p = 0.0025, Omnivore-Seed Eater, p = 0.0001. (b) Herbivores have relatively broader incisors. Kruskal-Wallis, p<0.0001. Steel-Dwass all pairs comparisons: Herbivore-Omnivore, p<0.0001; Herbivore-Seed Eater, p<0.0001, Omnivore-Seed Eater, p = 0.5249.
Fig 4.
Samples from Sterkfontein Member 4 (purple circles) and Swartkrans Member 1 (orange crosses) were treated as unknowns in our dietary model. Ellipses represent 50% of the distribution of the training specimens where blue = seed eater; green = omnivore; red = herbivore.
Table 3.
Dietary classifications of fossil specimens.