SECONDARY TIERING ON CRINOIDS FROM THE WALDRON SHALE (SILURIAN, WENLOCKIAN) OF INDIANA

Superbly preserved specimens of Eucalyptocrinites tuberculatus from th e Waldron Shale (Silurian, Wenlockian) of Indiana have been found with epibionts attached in living position to their stems. The rhynchonell id brachiopod Stegerhynchus indianense, the tabulate coral Favosites f orbesi, the annelids? Spirorbis and Cornulites, bryozoans, and rarely the ichnogenus Tremichnus utilized living crinoids as secondary tierin g surfaces. Crinozoans also attached to upright crinoid columns, and t heir holdfasts are the most abundant epibionts on pluricolumnals. Euca lyptocrinites crassus individuals contributed to the success of their epibionts by providing stable attachment surfaces elevated up to one m eter above the sediment-water interface. Although crinoid-epibiont rel ationships are frequently blurred by taphonomic processes, articulated crinoid specimens and encrusters on pluricolumnals suggest that secon dary tiering was a significant paleoecological element in the Waldron Shale.