Utility of postcanine dental dimensions for body size estimation in Mustela (Carnivora)

Mustela, one of the most species-rich and widespread genera of Carnivora, has a 4-million-year fossil record that mainly comprises permanent teeth, of which postcanines (premolars and molars) are most useful for taxonomic identification. To evaluate the utility of a simple method using linear measurements of permanent postcanines for body size estimation in extinct and extant Mustela, we correlated 25 linear measures of permanent postcanines with the condylobasal skull length (CBL; which in Mustela strongly correlates with both body mass and length) in three representative species of this genus (least weasel, M. nivalis; ermine, M. erminea; European polecat, M. putorius). Most postcanine measures were strongly correlated with CBL (Pearson's r > 0.70) in all species, which supports their utility for body size estimation in Mustela. Three of these measures (the mandibular first molar's mesiodistal length, the maxillary first molar's buccolingual width, and, to a lesser degree, the maxillary fourth premolar's mesiodistal length measured between the parastyle and protocone lobes) consistently showed a relatively high level of correlation with CBL in all species, and we therefore propose these measures as the best simple dental predictors of body size in Mustela. The differences in the strength of correlation of postcanine measures with CBL observed here between closely related species and between and within teeth emphasize the need for caution in using dental dimensions as a surrogate for body size.