Article: The British Permian crinoid 'Cyathocrinites' ramosus (Schlotheim)
Stephen K. Donovan, Neville T. J. Hollingworth and Cornelis J. Veltkamp
Although dissociated ossicles are locally common in the Upper Permian, Zechstein Cycle 1, Ford Formation reef of north-east England, the crinoid fauna is monospecific, consisting of 'Cyathocrinites' ramosus (Schlotheim). This species differs from Cyathocrinites s. s. in having a broad, bowl-shaped cup with wide radial arm facets and the right proximal plate of the anal tube incorporated into the calyx. The taxonomic position of 'C.' ramosus below order level is uncertain. 'C.' ramosus is interpreted as a rheophile and is found associated with a diverse fauna of mainly bivalves, gastropods, brachiopods, and bryozoans. A unique dorsal cup is known and dissociated ossicles from the crown and stem have been found, particularly the latter. The stem is xenomorphic. The proxistele was composed of low columnals and was particularly flexible. The mesistele was the principal organ of elevation of the crown. Dististele attachment was by a cirriferous runner. Two tentative palaeobiological deductions concerning the stem of 'C.' ramosus are that the distinctive pentastellate jugula of the axial canal were possibly adaptations for efficient autotomy and that, if present, peripheral through-going ligaments may have been about seven to nine columnals in length.