  We study the evolution of rapid neutron-capture process (r-process) isotopes
in the Galaxy. We analyze relative contributions from core collapse supernovae
(CCSNe), neutron star mergers (NSMs) and collapsars under a range of
astrophysical conditions and nuclear input data. Although the r-process in each
of these sites can lead to similar (or differing) isotopic abundances, our
simulations reveal that the early contribution of r-process material to the
Galaxy was dominated by CCSNe and collapsar r-process nucleosynthesis, while
the NSM contribution is unavoidably delayed even under the assumption of the
shortest possible minimum merger time.
