THE RARE BECOMES COMMON: NEW RECORDS OF UPPER PENNSYLVANIAN CRINOID SPINES WITH MULTIPLE PLANES OF REGENERATION

Crinoid spines showing evidence of regeneration following breakage are typically interpreted as evidence of attempted predation and are common in late Paleozoic strata. Published descriptions of regenerating crinoid spines previously consisted exclusively of specimens with a single plane of breakage and regeneration until very recently, when five primibrachials and two anal sac spines belonging to pirasocrinid cladids were described because they each contained two separate regeneration planes, indicating that the individual ossicles were broken and began regenerating twice during the lifespan of the crinoid. All of these specimens were collected from the Upper Pennsylvanian Ames Member of the Glenshaw Formation of eastern Ohio, USA. Newly reported material consisting of both primibrachial (1 specimen) and anal sac (13 specimens) spines from the Upper Pennsylvanian Wann and Barnsdall formations (Ochelata Group) of northeastern Oklahoma contribute to the record of pirasocrinid spines with multiple planes of regeneration. Some of these specimens occur within siliciclastic deposits, in contrast to the previously described material from Ohio, which was collected from carbonate units. Most importantly, these specimens demonstrate that the phenomenon of repeatedly regenerated pirasocrinid spines is more common and geographically widespread than previously recognized, and that its recent recognition most likely reflects material having been overlooked in collections rather than true exceptional rarity.