  The mass distributions of baryon resonances populated in near-central
collisions of Au on Au and Ni on Ni are deduced by defolding the $p_t$ spectra
of charged pions by a method which does not depend on a specific resonance
shape. In addition the mass distributions of resonances are obtained from the
invariant masses of $(p, \pi^{\pm})$ pairs. With both methods the deduced mass
distributions are shifted by an average value of -60 MeV/c$^2$ relative to the
mass distribution of the free $\Delta(1232)$ resonance, the distributions
descent almost exponentially towards mass values of 2000 MeV/c^2. The observed
differences between $(p, \pi^-)$ and $(p, \pi^+)$ pairs indicate a contribution
of isospin $I = 1/2$ resonances. The attempt to consistently describe the
deduced mass distributions and the reconstructed kinetic energy spectra of the
resonances leads to new insights about the freeze out conditions, i.e. to
rather low temperatures and large expansion velocities.
