Fig. 2.

Tooth pattern in alevins and fry. Graphical representation of the order of tooth development on the dentary in alevin and fry stage wild Atlantic salmon. a: 18.1 mm TL, b: 22.7 mm TL, c: 31.1 mm FL; d: 32.6 mm FL; e: 48.4 mm FL. Vertical lines represent (numbered) tooth positions (= tooth families); horizontal lines connect teeth in a similar stage of development. Lingual to the top, labial to the bottom of each figure. Teeth form a linear series, from position 1 (anteriormost position on the dentary) to 13. Up to around 22.7 mm TL, all teeth are first-generation teeth, but they differ in developmental stage, reflecting the time at which they were initiated. Four stages are distinguished: initiation and morphogenesis stage (small blue triangles), early cytodifferentiation stage (small light green triangles), late cytodifferentiation stage (large dark green triangles), tooth undergoing attachment (large light yellow triangles). Functional teeth are attributed to one of the following three states of functionality: newly attached functional teeth (large dark yellow triangles), mature functional teeth (large red triangles), functional teeth undergoing resorption (large purple triangles). Between 22.7 mm TL and 31.1 mm FL, replacement teeth appear (second-generation teeth), the developmental stage of which corresponds largely to the state of functionality of the predecessor. They will replace the first-generation teeth and be succeeded themselves by third-generation teeth. In (e) most of the functional teeth belong to the second generation (labeled ‘2’), the tooth in position 5 already belongs to the third generation (labeled ‘3’), whereas the functional teeth in the last three positions still belong to the first generation. Further explanation related to the pattern: see text.