Article: A new genus of inadunate crinoid with unique stem morphology from the Ashgill of Sweden
Stephen K. Donovan
Bodacrinus columnus gen. et sp. nov. from the Ashgill Boda Limestone of Sweden is described on the basis of dissociated stem material only. The column is unusual, being trimeric, and trilobate to sub-trapezoid in outline. Bodacrinus is presumed to be closely related to the disparid inadunate crinoid Ectenocrinus, the only other pelmatozoan known to have had a trimeric stalk. Relative stratigraphic positions indicate that Ectenocrinus may have been the ancestor of Bodacrinus. The stem of Bodacrinus is functionally adapted to articulate about an axis which is at 90° to the directions of movement in other bilaterally symmetrical columns such as those of myelodactylids.