  If the dark matter in galactic halos is made up of compact, macroscopic
objects (MO), such as black holes with $M_\MO >>M_{stars}$, gravitational
scattering will lead to kinematic heating of the stars. Observational
constraints on the amount of heating in the disk of the Milky Way put upper
limits on $M_\MO \ltorder 10^{6.3}\msun $. We find limits that are three orders
of magnitude more stringent by examining the heating limits in low mass stellar
systems, where higher densities of dark matter and lower relative velocities
disperse the stars in less than a billion years. Specifically, the structure
and kinematics of the Local Group member GR8 yield a limit of $M_\MO \ltorder
6\times 10^{3}\msun$. If the properties of the dark matter are universal these
results preclude the dominance of dark matter constituents in the
cosmologically interesting mass range $\sim 10^6\msun$ and limit them to $M_\MO
\ltorder 10^{3.7}\msun$. These results also rule out massive compact halo
objects as significant contributors to the kinematic heating of the Galactic
disk.
