Dental measures of extant lizards and fossil reptiles

Procolophonoids are hypothesized to be some of the first highly specialized herbivores to evolve in the aftermath of the end-Permian extinction. Hypotheses of procolophonoid diet are based on their unique dentitions: bulbous, multicuspid, differentiated teeth, specialized for feeding on fibrous plant matter. However, these conclusions are largely based on qualitative descriptions, and there has yet to be a broadscale, quantitative comparison of this group of fossil reptiles to modern ones. In our study, we use relatively simple measures of tooth shape and linear discriminant analysis (LDA) to predict dietary ecology from tooth dimensions and phylogenetic MANOVA to test for significant differences in tooth shape for different diets. We find that procolophonids are largely predicted as herbivorous but occupy different ecological niches from modern lizards and that simple methods return relatively similar results as complex methods. We hypothesize that the different mechanical challenges of Triassic-age flora produced a different 'kind' of herbivorous tooth from those observed in extant lizards, like those in procolophonids.