Predation scars preserved in Chesterian brachiopods: Probable culprits and evolutionary consequences for the articulates

Chesterian (Upper Mississippian) brachiopods from the Confusion Range of west-central Utah display repaired and unrepaired damaged valves attributable to attacks by shell-crushing sharks. Most diagnostic are tetrahedron-shaped indentations. The scars are situated anteriorly or laterally and only infrequently posteriorly. The predators were not species-selective among the common brachiopods except for a possibly epiplanktic rhynchonellid and chonetids which lack scars. Size-selectivity cannot be documented. Missisippian brachiopod taxa minimized loss to these predators by evolutionary development of large valves, spinosity, plication, cementation, quasi-infaunal mode of life or a continuously enlarging pedicle opening to facilitate strong pedicle attachment