Time evolution of radial stellar surface density (top) and vertical density (bottom) profiles from z = 1.5 to z = 0 for the disc components identified using GMM. The thickest solid grey line represents the total disc surface density profile at z = 0, while the dashed lines show exponential profiles with scale-lengths r_d, obtained by fitting the z = 0 surface density profile of each substructure. The vertical profiles are shown in a cylindrical bin within r_d ± 1 kpc (see e.g. Park et al. 2021), where r_d is calculated at each look-back time.