Predation scars offer insight into ancient predator-prey relationships and evolutionary processes. One approach to studying predation in fossils is through repair scars, which indicate a failed attempt at predation as the prey survives the attack and repairs its shell. A change in repair frequency is ambiguous as it may indicate either a change in the number of attacks on the prey or a change in the success of the predator. Size refugia, the size of the prey at which the predator will no longer take the prey, can potentially be used to differentiate between these two possibilities. The goal of this study is to examine predatory traces and size refugia in lineages of atrypide and strophomenide brachiopods to determine the relative performance of predators to prey through time in the Middle Devonian of Michigan.