Ecomorphological analysis was used to evaluate ecological relationships between 2 species of bats, Myotis auriculus and M. evotis. We imaged jaws and skulls of 242 specimens from 20 localities within the range of both taxa, emphasizing their southwestern regional area of sympatry. Using traditional morphometric and geometric morphometric methods, values for characters taken from dentaries of both species were analyzed in detail. Both methods detected character displacement and allowed us to detect differences in jaw size and shape within both species. The morphological difference in jaw shape is more emphasized within sympatric populations of M. evotis than in M. auriculus. This may indicate that competitive selection acts more on M. evotis. At sympatric localities, M. evotis displayed a shift to a more specialized trophic state with a trophic architecture (more highly placed articular process and robust molars) likely better at capturing beetles, whereas M. auriculus may have a greater advantage for capturing soft-bodied prey such as moths. On the other hand, the articular process is located lower relative to the toothrow of the dentary in M. auriculus. Also the shape of the jaw in this species suggests a weaker bite, more shearing force, and wider gape. All shape differences in jaw morphology are emphasized in sympatry, confirming active competitive interactions between these 2 species.