Boreholes in Devonian blastoids and their implications for boring by platyceratids

Complete, circular holes found on the thecae of 51 specimens of Devonian nucleocrinid blastoids are interpreted as biogenic in origin. Their morphology, their stereotyped position on the theca, and the lack of multiple borings, suggest that they represent predation or parasitism. Platyceratid gastropods are presumed to be the borers because (1) they occur in the same localities as the bored blastoids, (2) they have been found on thecae of other blastoids, and (3) their boring abilities have been previously demonstrated..