Echinoid grazing traces on ostreid shell-ground from the Pliocene Ficulle quarry (Central Italy)

Echinoid grazing traces present on ostreid valves constituting a shell-ground were studied. The shell-ground is preserved in sandy levels in the Pliocene clayey deposit cropping out near the Ficulle Village (central Italy). A dense frame made almost exclusively by rasping traces of regular echinoids referable to the ichnospecies Gnathichnus pentax Bromley was recognized. Ostreid shells dispersed in the surrounding clayey sediment show deep-tier endogenic traces, as Entobia, Gastrochaenolites, Caulostrepsis and Meandropolydora. Only on rare specimens rasping traces coexist with the latter ones. The different bioerosion trace-assemblages can be assigned to the two Gnathichnus and Entobia bioerosion ichnofacies as defined by Bromley and Asgaard (1993).