Fig. 4. Results from post-hoc Games-Howell pairwise comparisons of δ⁶⁶Zn values of enameloid from fossil and extant Otodus spp. and Carcharodon spp.

All assemblages and ages are combined for a given species, except for extant C. carcharias. Extant C. carcharias teeth are indicated with grey silhouettes. a Includes all O. megalodon populations, whereas (b) excludes the Japanese (Pacific) population, focusing on Atlantic and Tethys/Paratethys populations only. The boxes for n > 5 represent the 25th–75th percentiles (with the median as a horizontal line), and the whiskers show the 10th–90th percentiles. Significance level is indicated by “*” (p value < 0.05), “**” (p value < 0.005), “***” (p value < 0.0005) and “****” (p value < 0.00005). Measurement uncertainty is indicated at the 2 SD level. See also Supplementary Tables 11, 12. Otodus chubutensis (dark blue) and O. megalodon teeth (light blue) are coloured separately. All other samples are colour-coded following their genus. Source data are provided as a Source Data file. Silhouettes are not to scale.