High-resolution electron microscopy of the crystallites of fossil enamels obtained from various geological ages

To elucidate the stability of the central dark line (CDL) in biologically i nduced hydroxyapatite crystals, we examined the diagenetic changes on the m icrostructures of the crystallites during the course of fossilization. Usin g transmission electron microscopy, we investigated the enamel crystallites of fossil animals of various geological ages ranging from Pleistocene to C retaceous. Electron micrographs indicated that the microstructures and latt ice images of each crystallite in fossil enamels were well-preserved regard less of the thickness of the enamel layer, and the presence of CDLs in foss il enamel crystals was also confirmed. The results indicated that the micro structure of hydroxyapatite crystals containing lattice images of CDLs appe ar stable during long geological periods. In addition, we conclude that the existence of lattice images in apatite with CDLs may be an indicator for t he assessment of the evolution of dental enamel from fossil remains.