3 GHz radio continuum sizes (radii defined as half the major axis FWHM) derived in Paper II (and scaled to the revised redshifts and cosmology adopted here) plotted against the stellar masses derived in the present work (black squares). The SMGs at z> 3 are highlighted by green star symbols. For comparison, the red squares show the rest-frame UV/optical radii from Toft et al. (2014; also scaled to the present redshifts and cosmology). The upper size limits are indicated by arrows pointing down. The three dashed lines show the mass-size relationship of z ~ 2 compact, quiescent galaxies from Krogager et al. (2014), where the lower and upper lines represent the dispersion in the parameters (see text for details).