part of part of in taxon Selachii Chondrichthyes head spine appendage of head cephalic spine UBERON:0017621 cephalic spines One of the spines, probably denticle derivatives, occurring singly or in pairs just behind the orbit on the cheek area in some fossil sharks. May have occurred only in males and may have served to hold the female during copulation, e.g. in the Jurassic genera Hybodus, Asteracanthus and Acrodus.