Median values of the posterior distributions obtained for the stellar mass percentiles of 18 stacks, as a function of cosmic time (in Gyr) and redshift, coloured according to their velocity dispersions (in km s⁻¹). Redder colours indicate higher velocity dispersions (more massive galaxies), and bluer ones lower velocity dispersions (less massive ones). In the inset, we plot the observed spectra, normalised and in the wavelength range [4023, 6000] Å, with the same colour map.