This structure is very similar to that of the later "Protoceratops". This fossil preserves a single "Velociraptor" in the midst of battle against a lone "Protoceratops". A nocturnal lifestyle has been suggested for the primitive ceratopsian "Protoceratops". There is evidence that Protoceratops formed groups. Sereno (2000) included three genera in Protoceratopsidae&colon; "Protoceratops", "Bagaceratops", and "Graciliceratops". Alternatively, Dodson's analysis of structure sizes in large "Protoceratops" found that they were dimorphic. Significant sexual dimorphism has been noted in "Protoceratops" and several ceratopsids. More bones were initially included but later shown to belong to "Protoceratops". "Protoceratops", a type of ceratopsian, also shows signs of sexual dimorphism. One particularly famous specimen preserves a "Velociraptor" locked in combat with a "Protoceratops". It has been suggested that the griffins were inferred from the fossilized bones of "Protoceratops". Contemporary genera included "Velociraptor" and "Protoceratops". One group can be called Protoceratopsidae and includes "Protoceratops" and its closest relatives, all Asian. The large eyes of "Protoceratops" has been suggested as evidence for a nocturnal lifestyle. "Bainoceratops" may be synonymous with "Protoceratops".