  RXJ0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of
galaxies. Our analysis of stellar populations and star formation history in the
cluster covers 24 members and is based on deep optical spectroscopy from Gemini
North and imaging data from HST. Focusing on the 13 bulge-dominated galaxies
for which we can determine central velocity dispersions, we find that these
show a smaller evolution of sizes and velocity dispersions than reported for
field galaxies and galaxies in poorer clusters. The galaxies in RXJ0848.6+4453
populate the Fundamental Plane similar to that found for lower redshift
clusters with a zero point offset corresponding to an epoch of last star
formation at z_form= 1.95+-0.2. The spectra of the galaxies in RXJ0848.6+4453
are dominated by young stellar populations at all galaxy masses and in many
cases show emission indicating low level on-going star formation. The average
age of the young stellar populations (estimated from H-zeta) is consistent with
a major star formation episode 1-2 Gyr prior, which in turn agrees with
z_form=1.95. Galaxies dominated by young stellar populations are distributed
throughout the cluster. We speculate that low level star formation has not yet
been fully quenched in the center of this cluster may be because the cluster is
significantly poorer than other clusters previously studied at similar
redshifts, which appear to have very little on-going star formation in their
centers.
