Parasitism of Ordovician bryozoans and the origin of pseudoborings

Upper Ordovician trepostome bryozoans from the vicinity of Cincinnati, Ohio, USA, contain trace fossils that resulted from the overgrowth by the bryozoan of soft-bodied parasites that settled on the living colony. The resulting structures (pseudoborings) superficially resemble borings, and the term 'bioclaustration' is introduced to describe the process. The pseudoboring consists of groups or rows of sub-circular pits, connected by tunnels that were formed by the roofing-over of adventitious stolons by localized bryozoan growth. The structure reflects the external morphology of the parasite, and is named Catellocaula vallata ichnogen. and ichnosp. nov. A hydroid or colonial ascidiacian tunicate is suggested as the perpetrator.