ABSTRACT
One of the better-known and most enduring examples of biotic interactions in the fossil record is that between platyceratid gastropods and crinoids. The record of the co-occurrence of platyceratids and crinoids begins in the Ordovician and typically involves a single platyceratid attached to the crinoid calyx (Lane 1978, but see Baumiller 2002). Examples of the association exist for each geologic period of the Paleozoic with the exception of the Cambrian. There is consensus that the association is non-spurious and that the two organisms interacted for a long time during life (see Baumiller & Gahn 2002 for most recent review).
