Sixteen taxa of mud-bottom marine gastropods from the Pennsylvanian of north-central Texas were examined for direct evidence of unsuccessful attacks by crushing predators. Frequencies of these repaired shell fractures were determined for each taxon according to shell size and stratigraphic position within the Middle and Upper Pennsylvanian sequence. No directional trend in repair frequencies through time within the Pennsylvanian was found within any taxon. Trochiform and high-spired shells may have been better able to withstand attacks at larger shell sizes, though no such "size refuge" from predation seems in evidence for planispiral shells. Repaired fractures were more common for some high-spired forms and trochiform taxa than for planispiral shells. Estimates of repair frequencies among fusiform shells are less reliable. Among six trochiform taxa, higher-spired and turreted taxa displayed higher repair frequencies than low-spired forms. As architectural themes, high spires and taller trochiform shape may have provided more potential for crushing resistant morphological variations than the low trochiform and planispiral designs. The decline of diversity among low trochiform and planispiral forms, and the diversification of higher-spired taxa during the Mesozoic reorganization of the benthic biosphere may in part have been driven by the selection for anti-crushing shell variations suggested in this Pennsylvanian assemblage.