Hypsilophodon_foxiStegoceras_validusLiaoceratops_yanzhiguouensisArchaeoceratops_oshimaiAsiaceratops_salsopaludalisYamaceratops_gobiensisGraciliceratops_mongoliensisBagaceratops_rozhdestvenskyiProtoceratops_andrewsiZuniceratops_christopheriCentrosaurus_apertusTriceratops_horridusMontanoceratops_cerorhynchusLeptoceratops_gracilisUdanoceratops_tahizhoviPrenoceratops_peiganensisPsittacosaurus_mongoliensisPsittacosaurus_sinensisChaoyangsaurus_youngiIVPP_V12722OsteologyMaximum ParsimonyBased on reanalysis of the original matrix.Makovicky_et_Norell_2006aaMakovicky_et_Norell_2006ab