C. carcharias tooth with crenulations in the blade.
Palaeocarcharodon orientalis with crenulations in the blade.
Crenulations, also known as wrinkles, occur in a number of species and are diagnostic in Isurus retroflexus, Cretodus borodini, and Palaeogaleus vincenti, for examples from Kent. Kent describes the I. retroflexus condition as "short vertical wrinkles along basal margin of labial coronal surface." Kent is describing wrinkles in the enameloid of the crown. However, there are some examples of teeth in which the crenulations extend beyond the crown into the root.
