HYDROXYAPATITE VARIETIES IN RECENT FISH SCALES

Abstract

. Mineralogy of apatite in the scales of Recent sharks, rays, and teleosts was studied using X-ray diffraction analysis. All the studied fish scales are composed of hydroxyapatite with different lattice parameters. The apatite in the scales ofRecent rays and teleosts has lattice parameters within the range of a=9.44-9.46 апа с = 6.87-6.88, which is comparable to the apatite in Recent vertebrate bones. The shark scale apatite has lattice parameters a = 9.40-9.41 and c = 6.87-6.88, closer to the apatite in Recent lingulate brachiopod shells. The distinct lattice parameters reflect differences in the chemical composition, first of all, in the content of hydroxyl, fluorine, and carbonate anions. These differences between the higher taxa of Recent fishes are significant from an evolutionary perspective and have implications to the interpretation of the mineralogy of fossil vertebrate skeletons.