The clade Neoceratopsia include all ceratopsians more derived than psittacosaurids . Another subset of neoceratopsians is called Coronosauria , which currently include all ceratopsians more derived than Auroraceratops . Coronosaurs show the first development of the neck frill and the fusion of the first several neck vertebrae to support the increasingly heavy head . Within Coronosauria , three groups are generally recognized , although the membership of these groups vary somewhat from study to study and some animals may not fit in any of them . One group can be called Protoceratopsidae and include Protoceratops and its closest relatives , all Asian . Another group , Leptoceratopsidae , include mostly North American animals that are more closely related to Leptoceratops . The Ceratopsoidea include animals like Zuniceratops , which are more closely related to the family Ceratopsidae . This last family include Triceratops and all the large North American ceratopsians and is further divided into the subfamilies Centrosaurinae and Ceratopsinae ( also known as Chasmosaurinae ) .