part of part of dorsal region element dorsal fin skeleton dorsal fin ceratotrichial spine (elasmobranchs) UBERON:4300101 A small to large enameloid-covered, dentine-cored spine located on the anterior margins of one or both of the dorsal fins, found on bullhead sharks (Heterodontiformes), many dogfish sharks, fossil (but not living) batoids, chimaeroids, but lost entirely or buried in the fin bases of other shark-like fishes [Compagno, Sharks of the World]. ceratotrichium Wasila M Dahdul