We measure the central stellar velocity dispersion function for quiescent galaxies in a set of nine northern clusters in the redshift range 0.18 1.5 and within R200. The cluster velocity dispersion functions all show excesses at s ? 250 km s-1 compared to the field velocity dispersion function. The velocity dispersion function slope at large velocity dispersion (s > 160 km s-1) is steeper for more massive clusters, consistent with the trend observed for cluster luminosity functions. The spatial distribution of galaxies with large velocity dispersion at radii larger than R200 further underscores the probable major role of dry mergers in the growth of massive cluster galaxies during cluster assembly.
