LAUSR

Abstract Dental microwear texture analysis (DMTA) has been instrumental in reconstructing dietary ecology of extinct and extant carnivorans. Current sampling methods for canids focus on lower second molars (m2), where the grinding of flesh and bone captures dental microwear indicative of diet. However, dental microwear on other biomechanically analogous grinding facets (i.e. the talonid basin on the lower carnassial, m1) might be comparable and could help dramatically increase sample sizes of fossil specimens, as carnassials are more frequently recovered and identifiable than lower m2s. Here, we quantify the degree to which dental microwear textures between grinding facets on lower first and second molars are similar in two species of extant canids, coyotes (Canis latrans) and gray wolves (Canis lupus). Casts of paired m1s and m2s for each individual were sampled from museum collections and analyzed for three microwear parameters that correlate with diet in carnivorans: anisotropy, complexity, and textural fill volume. Within wolves, the m1 talonid and m2 are indistinguishable in all DMTA parameters. In coyotes, grinding facets of the m1 talonid and m2 are indistinguishable in complexity and textural fill volume, but anisotropy values of m1s are significantly lower than those of m2s. Differences in anisotropy between species were unlikely to be driven by biomechanical shifts in bite force between the m1 talonid and m2, but could stem from a combination of subtle morphological variation and intra-tooth variation. Overall, these data suggest that regions across molars with similar functions yield similar dental microwear textures. Finally, to demonstrate the effect of increased sample size, we show how the combination of DMTA data from lower m1 talonids and lower m2s of the hypocarnivorous Phlaocyonini canids from the John Day Formation of eastern Oregon, USA, alters the size and shape, but not position, of their reconstructed dietary “niche” space and hence interpretations about dietary behavior.