  We consider a sample of 51 distant galaxy clusters at 0.15<z<0.9 (<z> about
0.3), each cluster having at least 10 galaxies with available redshift in the
literature. We select member galaxies, analyze the velocity dispersion
profiles, and evaluate in a homogeneous way cluster velocity dispersions and
virial masses. We apply the same procedures already recently applied on a
sample of nearby clusters (z<0.15, Girardi et al. 1998b) in order to properly
analyze the possible dynamical evolution of galaxy clusters. We remark problems
induced by the poor sampling and the small spatial extension of the sampled
cluster region in the computation of velocity dispersion. We do not find any
significant difference between nearby and distant clusters. In particular, we
consider the galaxy spatial distribution, the shape of the velocity dispersion
profile, and the relations between velocity dispersion and X-ray luminosity and
temperature. Our results imply little dynamical evolution in the range of
redshift spanned by our cluster sample, and suggest that the typical redshift
of cluster formation is higher than that of the sample we analyze.
