Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum Vol. 50, No. 1

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.