Diagnostic criteria for identification of seashell as a trephination implement

Scanning electron microscopy has been applied to experimentally cut bone samples and an ethnographical example of trephination on a human skull in order to produce diagnostic criteria for the identification of mollusc shells as cutting implements used in trephination. Shell scrapes are identifiable by parallel striations in the direction of cut, crossed at 90° by chatter marks caused by uneven movement of the fragile shell-edge across the bone surface.