FISHERY BULLETIN: VOL. 82, NO. 1 



Enamel 



Enamel 



Prenatal dentine 



Neonatal line 



Approximate region 

 and angle of GLG and 

 label measurements 



Cementum 



ABC P Pulp cavity 

 Tetracycline margin 

 labels , 



654 3 2 1 



i i 



Dentinal 

 GLGs 



VIEW IN UV LIGHT 



VIEW IN PLAIN LIGHT 



B 



Periods of treatment 



Dentinal labels 



ig78 197g 



1980 



.i i i i i i i i i i I 



Death 



Pulp cavity 



FIGURE 1 .—Line drawing of hypothetical dolphin tooth in thin section showing appearance of TCL labels, A, B, C, D, 

 under ultraviolet light (1A, left-hand side) and dentinal growth layer group (GLG) layering patterns under plain 

 transmitted light (IB, right-hand side), and standard positions in tooth where label and GLG thickness are measured. 

 1 C illustrates method of identifying labels in tooth section with TCL treatment dates by comparing relative thickness 

 and spacing of labels with treatment periods. 



210 



