Opinions from P. C. Sereno 2000
- 'Archaeoceratops belongs to Neoceratopsia'
- 'Archaeoceratops oshimai belongs to Archaeoceratops'
- 'Asiaceratops is a nomen dubium'
- 'Asiaceratops salsopaludalis is a nomen dubium'
- 'Bagaceratops belongs to Protoceratopsidae'
- 'Bagaceratops rozhdestvenskyi belongs to Bagaceratops'
- 'Breviceratops is a subjective synonym of Bagaceratops'
- 'Centrosaurinae belongs to Ceratopsidae'
- 'Ceratopsia was reranked as a unranked clade and belongs to Marginocephalia'
- 'Ceratopsidae belongs to Ceratopsoidea'
- 'Ceratopsinae belongs to Ceratopsidae'
- 'Ceratopsoidea belongs to Coronosauria'
- 'Chaoyangsaurus belongs to Neoceratopsia'
- 'Chaoyangsaurus youngi belongs to Chaoyangsaurus'
- 'Coronosauria belongs to Neoceratopsia'
- 'Domocephalinae is a nomen vanum'
- 'Goyocephale belongs to Pachycephalosauria'
- 'Goyocephale lattimorei belongs to Goyocephale'
- 'Graciliceratops belongs to Protoceratopsidae'
- 'Graciliceratops mongoliensis belongs to Graciliceratops'
- 'Homalocephale belongs to Pachycephalosauria'
- 'Homalocephale calathocercos belongs to Homalocephale'
- 'Leptoceratops belongs to Neoceratopsia'
- 'Microceratops is a nomen dubium'
- 'Microceratops gobiensis is a nomen dubium'
- 'Microceratops sulcidens is a nomen dubium'
- 'Micropachycephalosaurus is a nomen dubium'
- 'Micropachycephalosaurus hongtuyanensis is a nomen dubium'
- 'Montanoceratops belongs to Ceratopsoidea'
- 'Neoceratopsia belongs to Ceratopsia'
- 'Ornatotholus belongs to Pachycephalosauria'
- 'Pachycephalosauria was reranked as a unranked clade and belongs to Marginocephalia'
- 'Pachycephalosauridae belongs to Pachycephalosauria'
- 'Pachycephalosaurinae belongs to Pachycephalosauridae'
- 'Pachycephalosaurus belongs to Pachycephalosaurinae'
- 'Prenocephale belongs to Pachycephalosaurinae'
- 'Prenocephale prenes belongs to Prenocephale'
- 'Protoceratops belongs to Protoceratopsidae'
- 'Protoceratops andrewsi belongs to Protoceratops'
- 'Protoceratops kozlowskii is a subjective synonym of Bagaceratops rozhdestvenskyi'
- 'Protoceratopsidae belongs to Coronosauria'
- 'Psittacosaurus belongs to Ceratopsia'
- 'Psittacosaurus mazongshanensis is a nomen dubium'
- 'Psittacosaurus meileyingensis belongs to Psittacosaurus'
- 'Psittacosaurus mongoliensis belongs to Psittacosaurus'
- 'Psittacosaurus sattayaraki is a nomen dubium'
- 'Stegoceras belongs to Pachycephalosauridae'
- 'Stenopelix belongs to Pachycephalosauria'
- 'Stenopelix valdensis belongs to Stenopelix'
- 'Stygimoloch belongs to Pachycephalosaurinae'
- 'Tholocephalidae is a nomen vanum'
- 'Turanoceratops belongs to Ceratopsoidea'
- 'Turanoceratops tardabilis belongs to Turanoceratops'
- 'Tylocephale belongs to Pachycephalosaurinae'
- 'Tylocephale gilmorei belongs to Tylocephale'
- 'Udanoceratops belongs to Neoceratopsia'
- 'Udanoceratops tschizhovi belongs to Udanoceratops'
- 'Wannanosaurus belongs to Pachycephalosauria'
- 'Wannanosaurus yansiensis belongs to Wannanosaurus'
- 'Yaverlandia belongs to Pachycephalosauria'