Predators exert strong selective pressures on prey, which respond by evolving defenses. Armor is one such defense which can vary in the presence of different levels of predation pressure. However studies on this have been uneven in scope, limiting their usefulness for deriving general conclusions concerning predator effects on armor evolution. This study investigates the evolutionary covariation of turtle shell strength and the bite forces of turtle predators across the turtle phylogeny. Shell strength is assessed through finite element (FE) modeling. Predator overlap with turtle ranges is assessed through GIS and bite forces are collected from the literature; these are combined to produce two measures of predation pressure. Evolutionary correlations are consistently seen between all variables, indicating that strong predators may impose selection pressure for increased shell strength. However, these correlations are consistently weak. A number of potential explanations could account for this: trade-offs between turtle shell strength and other shell functions, selection in response to predation risk rather than predator presence, and selection acting on shell strength in juveniles or subadults rather than adults. Trade-offs have been documented, and variable strength of selection in different environments support the second hypothesis. Future work is necessary to support the third hypothesis. This study joins others in demonstrating that the evolution of armor has a complex relationship with predation.