* Dietary inferences are a key foundation for paleoecological, ecomorphological and macroevolutionary studies because they inform us about the direct relationships between the components of an ecosystem. However, we need to consider the range of dietary variation we want to investigate and characterize before choosing a proxy. The goal of the present work is to evaluate the differences in dietary discrimination power between our new method, the multidimensional multi-proxy dental morphology analysis (MPDMA) and unidimensional dental morphology proxies such as orientation patch count (OPCR), relief index (RI) or slope. * In order to do that, we three-dimensionally scanned the dentitions of 134 extant mammals including 28 marsupials (order Diprotodontia) and 106 placentals (orders Carnivora, Primates and Rodentia) and classified their diets using a new classification scheme that emphasizes the primary resource in a given diet. Diet categories included herbivory, carnivory, frugivory, granivory, insectivory, fungivory, gumivory and generalist. * Unidimensional proxies significantly discriminate (P < 0·05) between one or two diet categories on the one hand and the rest on the other. For example, OPCR discriminates well between carnivorous and non-carnivorous species. However, none of the individual proxies discriminate all eight dietary categories. Multi-proxy dental morphology analysis demonstrates significant morphological differences across diets (MANOVA, d.f. = 7; F = 7·56; P < 0·05) and correctly discriminates diet for 67-82% of the specimens in the data set including and excluding rodents respectively. * Combining different morphological variables makes it possible to draw better dietary inferences and fully represent the multidimensional nature of dental morphology and dietary specializations. Our results have important applications in ecological, paleoecological and evolutionary research.
