Secondary tiering on crinoids from the Waldron Shale (Silurian: Wenlockian) of Indiana

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