Development of the dentition in a close series of accurately staged and aged embryos of Alligator mississippiensis was studied by macroscopy, light microscopy, scanning electron microscopy (SEM) and detailed reconstructions. Dental development in the lower jaw up to stage 18; day 26 is described in this paper. In the lower jaw, the first formed tooth germ appears at stage 14 in tooth family 3; the second at stage 15 in family 6; the third, fourth, fifth, sixth and seventh at stage 17 in families 12,2,4,9 and 16, respectively. Neither ‘Zahnreihen’ nor ‘perfect alternation’ theories of tooth initiation explain the data. Rather the present data suggest that initiation of teeth is related to jaw growth, the distance between existing teeth and the size and developmental maturity of the latter. Each tooth is postulated to have a ‘zone of inhibition’ around it. The first formed embryonic teeth are discernible by macroscopy and SEM as surface elevations (projecting tooth germs). The dental tissues of these are poorly differentiated and lack enamel. Projecting tooth germs sink into the jaw mesenchyme, their dental epithelia degenerate and they persist as non-functional dentine rudiments for varying periods before becoming completely resorbed or shed. Formation of the dental lamina occurs by an overgrowth of the operculum (on which a distinct line of cobblestoned cells is visible by SEM) and closure of the dental furrow, as well as by the formation of a dental prolamina. The scaled fate maps and descriptive appearances of the developing alligator dentition highlight its value for future experimental studies of pattern formation and positional information.