Borings in Devonian and Mississippian blastoids (Echinodermata)

Abstract

Previously undescribed holes on the calyx of single specimens of the blastoids Pentremites and Cordyloblastus are circular in plan view, penetrate the test at a right angle, and are found in the interambulacral region. The same features characterize holes on 23 specimens of the Mississippian blastoid Orophocrinus. The holes are interpreted as biogenic in origin; examples of multiple complete holes on individual specimens and of incomplete holes on some blastoids indicate that the holes represent parasitism rather than predation. The similarity of these holes to those previously described in nucleocrinids and crinoids suggests that they were produced by platyceratid gastropods or closely related taxa.