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Teeth and their tissues, dentin and enamel, have a long, well-defined history. Their origin was traced back to the extra-oral dermal skeleton of early jawless vertebrates, approximately 500 million years ago, mya (see reviews in Huysseune and Sire, 1998; Smith and Coates, 2000; Sire and Huysseune, 2003). Once recruited into the mouth in early gnathostomes, circa 450 mya, teeth were subjected to strong selective pressure due to their crucial function. This explains why teeth, and particularly their developmental processes, organization and structural components, were conserved nearly unchanged through geological times. In mammals, as in most tetrapod taxa, teeth are covered by a thick and highly mineralized, protective tissue, enamel. The amelogenin gene (AMEL) encodes the major protein of enamel (90% of the organic matrix). Recent molecular analyses have brought insights into the evolutionary pattern …