Up is down: testing the equivalence in dental wear patterns of the upper and lower carnassial.

The analysis of dental microwear is widely applied to reconstruct the diet of different fossil species. Dental microwear is usually sampled on worn facets, that are produced during food processing. To maximize the sample size, tooth wear is sampled on upper and lower teeth assuming equality in wear patterns between two homologous opposite facets. Anyhow, previous research on fossil herbivores have highlighted potential discrepancies between upper and lower teeth, particularly in non-homologous facets, raising questions about the validity of this practice. Here we test if wear of the homologous facets of the slicing portion of the carnassials in four species of extant carnivores can be analysed without distinction, resulting in the same ecological evidence. To achieve a high-resolution representation of these patterns, we used Dental Microwear Texture Analysis. The results of similarity tests validated that there is no statistically significant difference between SSFA attributes and, moreover, they are equivalent. This statistical equivalence opens new possibilities for the future by effectively doubling the data availability, at least for extant carnivores. In addition, it can help overcome the scarcity of data on tooth wear in fossil carnivores.