Fig. 2From: A universal power law for modelling the growth and form of teeth, claws, horns, thorns, beaks, and shellsVertebrate teeth grow following the power cascade model, showing linear change in log Radius with log Distance from tip. a Measurement of Radius and Distance for Tyrannosaurus rex (UWBM 99000) lower right tooth 2 (shown in light green in b), which fits a linear model with R2 = 0.997. Radius = √ (cross-sectional area/π). b Teeth from all vertebrate groups show a linear pattern on log-log axes. Linear regression gives R2 > 0.994 for all teeth shown, other than snake fang where R2 = 0.954 (R2 = 0.999 excluding base 20%). EDJ, enamel-dentine junction. c Power cones vary depending on Slope (from conical to blunt) and Intercept (from wide to narrow) of the Log Radius-Distance plotBack to article page