Ostracods are common yet understudied prey in the fossil record. We document drill holes in Paleocene (Danian) ostracods from central Argentina using 9025 specimens representing 66 species. While the assemblage-level drilling percentage is only 2.3%, considerable variation exists within species (0.3–25%), suggesting prey preference by the drillers. This preference is not determined by abundance because no significant correlation is found between species abundance and drilling percentages. Seven methods were used, some of which are new, to quantify drilling percentages for the abundant and commonly drilled Togoina argentinensis. The obtained range from 9.9 to 14.6% suggests that drilling percentages are fairly insensitive to the method used, implying that comparisons across studies appear possible. Using this knowledge, the Cretaceous-Paleogene mass extinction had limited effect on drilling intensity in ostracod prey. The cylindrical (Oichnus simplex) and parabolic (O. paraboloides) drill holes from Argentina may have been primarily caused by muricid and naticid gastropods. Two oval drill holes (O. ovalis) are morphologically similar to octopod drill holes, but their small size, the fact that extant octopods are unknown to drill ostracods and the absence of such holes in co-occurring gastropods preclude ascription to a predator. Drill holes are located preferentially in the median and dorsal regions, where most soft tissue including the adductor muscle is located. Drilled specimens are statistically taller than non-drilled specimens for T. argentinensis and larger predators selected larger ostracods. The drilling percentage is significantly higher in ornamented ostracods, suggesting that ornamentation is not functional against drilling predators here.