Particles belonging to the main (blue dots) and second (red dots) progenitors at redshift 0.06 are shown at different redshifts (given in the top left of each panel). Black dots indicate the other particles that belong to the halos at z = 0. Masses are given in h⁻¹M_⊙ for each halo. In the last four gigayears (after z = 0.4), there are no mergers between the most massive progenitor and a progenitor with a mass larger than about a tenth of the mass of the halos apart from that with the second progenitor.