LOWER ORDOVICIAN (LATE ARENIG) VERMIFORICHNUS SHELL BORINGS FROM NEW WORLD ISLAND, NEWFOUNDLAND

Abundant shell-borings are reported in brachiopods from the Lower Ordovician Summerford Group, New World Island, Newfoundland. Host brachiopods lived in turbulent shallow water and are preserved in a calcareous tuff within an extrusive volcanic sequence. Borings occur as natural casts in voids left by diagenetic dissolution of the host brachiopod shell. Borings are indistinguishable in size, shape, and preferred orientation (perpendicular to host commissure) from latter Vermiforichnus. The borings therefore probably represent the traces of spionid annelids which lived commensally within the shells of live hosts. This report extends the age range of Vermiforichnus into the Early Ordovician and represents one of the oldest known examples of a specialized commensal relationship. The find also further documents the rapid radiation of shell-encrusting and shell-boring taxa that occurred within the Lower Ordovician.