  M85 is a peculiar S0 galaxy in Virgo and is a well-known merger remnant. In
this paper, we present the first spectroscopic study of globular clusters (GCs)
in M85. We obtain spectra for 21 GC candidates and the nucleus of M85 using the
Gemini Multi-Object Spectrograph on the Gemini North 8.1 m telescope. From
their radial velocities, 20 of the GCs are found to be members of M85. We find
a strong rotation signal of the M85 GC system with a rotation amplitude of 235
km s$^{-1}$. The rotation axis of the GC system has a position angle of about
161$^{\circ}$, which is 51$\rlap{.}{^\circ}$5 larger than that of the stellar
light. The rotation-corrected radial velocity dispersion of the GC system is
estimated to be $\sigma_{\rm r,cor} = $ 160 km s$^{-1}$. The rotation parameter
$\Omega R_{\rm icor}/\sigma_{\rm r,cor}$ of the GC system is derived to be
1.47$^{+1.05}_{-0.48}$, which is one of the largest among known early-type
galaxies. The ages and metallicities of the GCs, which show the same trend as
the results based on Lick indices, are derived from full spectrum fitting
(ULySS). About a half of the GCs are an intermediate-age population of which
the mean age is $\sim$ 3.7 $\pm$ 1.9 Gyr, having a mean [Fe/H] value of --0.26.
The other half are old and metal-poor. These results suggest that M85
experienced a wet merging event about 4 Gyr ago, forming a significant
population of star clusters. The strong rotational feature of the GC system can
be explained by an off-center major merging.
