The ability to capture and hold specific prey is likely under strong selective pressure and should allow for predictable convergent modifications. Skinks are difficult prey to capture due to their hard scales, and examples of specializations for scincivory abound within Serpentes. However, direct comparisons between related specialists or quantified intraspecific differences have not been attempted. A model system would contain several taxa with various diet specializations, such as the genus Lampropeltis. Lampropeltis elapsoides is a skink specialist, while diet across the subspecies of Lampropeltis triangulum are variable. Lampropeltis triangulum syspila shifts from ectotherms to a generalist diet over ontogeny, while Lampropeltis triangulum triangulum ingests endotherms throughout. We utilized preserved specimens and computerized tomography to compare teeth across ontogeny and quantified the size and shape variation using semilandmark analysis to test for dietary specializations. There is significant change in tooth size and size-disparity in all three taxa at a specific body size, with consistent specializations shown in quantified tooth shape and jaw descriptions in smaller snakes. This suggests an ontogenetic transition that correlates to a change in diet away from scincivory that is consistent with the dietary hypothesis for L. elapsoides and L. t. syspila. These data suggest heterochrony can explain the specializations of L. elapsoides; it has a smaller maximum size and maintains specializations throughout its life, whereas L. t. syspila transitions its diet at a larger size. Dietary observations in Lampropeltis t. triangulum could be explained by an unknown dietary shift or ancestral condition.