ARISTOCYSTITES, A RECUMBENT DIPLOPORID (ECHINODERMATA) FROM THE MIDDLE AND LATE ORDOVICIAN OF BOHEMIA, CSSR

The Ordovician diploporid Aristocystites Barrande lived recumbently on the seafloor but never evolved marginal frame plates or flexible tesselated surfaces. Flume studies on 1:1 scale models clearly indicate that this genus lived attached by an aboral holdfast with the aboral end of the theca facing into the current. The oral end, with its paired brachioles, fed in vortices generated in the lee of the theca. Optical current velocities for feeding probably ranged from 6 to 18 cm/sec. Other species synonymized with Aristocystites bohemicus Barrande from the Caradocian Zahorany Beds of Bohemia are A. desideratus, A. grandisculum, A. idealis, and A. rudis. Aristocystites metroi Parsley and Prokop, n. sp., is described from the upper Zahorany shale facies and the Bohdalec Formation from the Prague area. -from Author