not been prepared or studied as of 2008. [ 2 ] A partial adult skull from the Bayan Mandahu Formation has been assigned to a distinct species, Velociraptor osmolskae . [ 2 ] Paleoecology Illustration of V. mongoliensis All of the fossil sites that have yielded Velociraptor remains preserve an arid environment with fields of sand dunes and only intermittent streams , although the younger Barun Goyot environment seems to have been slightly wetter than the older Djadochta. [ 22 ] The posture of some complete fossils, as well as the mode of preservation most show within structureless sandstone deposits, may show that a number of specimens were buried alive during sandstorm events common to the three environments. [ 2 ] Many of the same genera were present across these formations, though they varied at the species level. For example, the Djadochta was inhabited by Velociraptor mongoliensis , Protoceratops andrewsi , and Pinacosaurus grangeri , while the Bayan Mandahu was home to Velociraptor osmolskae , Protoceratops hellenikorhinus , and Pinacosaurus mephistocephalus . These differences in species composition may be due a natural barrier separating the two formations, which are relatively close to each other geographically. [ 2 ] However, given the lack of any known barrier which would cause the specific faunal compositions found in these areas, it is more likely that those differences indicate a slight time difference. [ 20 ] Classification Velociraptor is a member of the subfamily Velociraptorinae , a derived sub-group of the larger family Dromaeosauridae.