Density of COSMOS2015 star-forming (blue) and quiescent (red) galaxies (according to NUVrJ classification) in the sSFR–z plane. The solid black line shows the fixed sSFR threshold used in this work; dashed lines indicate the time-dependent thresholds of Pacifici et al. 2016 (green) and Franx et al. 2008 (purple). Thresholds diverge at z > 2, but converge near z ∼ 0.7–0.9, where most COSMOS galaxies lie. The bottom histograms show the redshift distribution of galaxies that would change classification under the two time-dependent thresholds, as reported in the legend.