Regeneration in a stellarocrinid cladid crinoid axillary spine from the Upper Pennsylvanian Wann Formation of northern Oklahoma, USA

Abstract

Cladid crinoid crown spines showing evidence of breakage followed by regeneration are relatively common and generally regarded as evidence of attempted predation, most likely by snipping fishes. Herein, we describe a minute spine from the Upper Pennsylvanian (Kasimovian) Wann Formation of northeastern Oklahoma, USA, that represents a stellarocrinid axillary spine. The specimen con-tains a single plane of breakage and subsequent regeneration, making this the first detailed descrip-tion of predation-generated regeneration in an ossicle of this type, and one of few examples of re-generation in a stellarocrinid prey target. Predation-generated breakage of stellarocrinid spines is not surprising and probably reflects a general lack of attention to isolated crinoid ossicles. This occur-rence of attempted predation provides further suggestive evidence that such biotic interactions likely drove the spinosity characteristic of this group.