Paleoecology ofSphenothalluson an Upper Ordovician hardground

摘要

A hardground from the Upper Ordovician Dillsboro Formation near Dillsboro, Indiana, U.S.A., preserves an assemblage of encrusting and boring fossils on both top and bottom surfaces. The slab is inferred to have been an undercut ledge, and the dominant fossils of the assemblage, holdfasts of the tube‐building wormSphenothallusand trepostome bryozoans, are prevalent on both sides. The clumping ofSphenothallusholdfasts has been statistically demonstrated using a nearest‐neighbor technique.Sphenothallushas also been shown to withstand overgrowth in interactions with bryozo