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The origin of ultra-compact dwarfs(UCDs)– objects larger and more massive than typical globular clusters(GCs),but more compact than typical dwarf galaxies – has been hotly debated in the 15 years since their discovery.In this contribution,I will present our recent results on the kinematical properties of an unprecedentedly large sample of UCDs around the Virgo central cD galaxy – M87.Our sample of UCDs(118)increases the number of known Virgo UCDs by a factor of three,and provides by far the best opportunity to probe the kinematics of UCDs as a population.We found that most of the Virgo UCDs are not consistent with simply being the luminous or extended tail of otherwise normal GCs,and the centrally confined spatial distribution and distinct kinematics of UCDs open the possibility that many UCDs may be the remnants of primordial compact galaxies.