Standardized major axis equation shown in the format y = mx + b. Symbols: (°) represents differences at 90 to 95% (0.1 <P > 0.05); (*) at 9 to 99% (0.05 <P > 0.01); and (**) at greater than 95% (P < 0.01). Otherwise, P-values are > 0.1. All P-values are adjusted for multiple comparisons using FDR. Significant differences using 95% CI are assessed on whether the intervals overlap or not; non-overlapping comparisons are indicated with an asterisk (*). acomparisons based on a subset of the mammalian dataset that has the same body mass range as the total reptilian dataset [See Additional file 2, Table S1]; mCI, slope comparisons based on 95% confidence intervals; mP, slope comparisons based on likelihood ratio test; bCI, intercept comparisons based 95% confidence intervals; bP, intercept comparisons based on two-tailed t-test; b'P, t-test comparison of adjusted intercepts to the minimum value along the x-axis; BM, body mass; CF, femoral circumference; FDR, false discovery rate; LH, humeral length; CH, humeral circumference; CH+F, total humeral and femoral circumference; LF, femoral length.