Evolution of Illustris galaxies on the R_s versus M_s plane from z = 4 to z = 0. There are eight values of redshift along each line. The position of each galaxy at each redshift is marked by a point of different colour. The colour code is as follows: blue (z = 4.0), medium-blue (z = 3.0), light-green (z = 2.2), green (z = 1.6), cyan (z = 1.0), magenta (z = 0.6), coral (z = 0.2), and red (z = 0). The solid lines are the best fits of the Illustris data for z = 0 in the domain of massive galaxies M_T ≥ 10¹¹ M_⊙ (red), and of the Bernardi et al. (2010) ETGs by Chiosi et al. (2012; green). Here we show 20 cases randomly chosen from the whole sample.