Same size–stellar mass relations as in Fig. 8 but colour-coded according to their age as estimated using the g − r colour at the fixed metallicity value stated in the colour bar. While the differences between the relations using -1.71 and -1.31 are minor, there are larger differences in individual points with the -0.71 relation. However, given that we are interested in relative age distributions, the bifurcation we report in this work remains unchanged when considering either of those relations separately (see text for discussion).