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

Abstract

A small shell-ground made of disarticulated valves of ostreids, preserved in a small sandy area in the Pliocene clayey deposit outcropping near the Ficulle Village (central Italy), exhibit a dense and almost exclusive colonization by rasping traces of regular echinoids  referable to the ichnospeciesGnathichnus pentax Bromley.   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 two bioerosion traces assemblages  can be assigned to the two Gnathichnus ad Entobia  bioerosion ichnofacies   as defined by  Bromley and Asgaard ( 1993).