Mass and the morphology-density relation

We examine the morphology-density relation for complete mass-limited samples of galaxies from five X-ray luminous clusters from z = 0.023 to z = 0.83. We find no change in the morphology-density relation for our complete sample of 366 galaxies with masses > 10(10.8) M-circle dot (roughly 0.4 M-star at z = 0). In contrast, we find a change in the early-type fraction with redshift that is in good agreement with previous work in a luminosity-selected sample (0.4L(star)) of 478 galaxies from the same parent data. Our results indicate that the galaxies that dominate the morphology-density relation, and its evolution, have masses < 10(10.8) M-circle dot.