The anatomy and homologies of the ceratopsid syncervical

Abstract

The Ceratopsidae and all other members of the Ceratopsia, except Psittacosaurus and Hongshanosaurus (Family: Psittacosauridae), comprise the order of Neoceratopsia (sensu Sereno, 2000). All members of this group can be distinguished from psittacosaurids and other members of the Ornithischia by fusion of the anterior-most vertebrae (Fig. 1). The resulting structure is called the syncervical (Ostrom and Wellnhofer, 1986) or cervical bar (Langston, 1975). This fusion probably occurred in order to stabilize the neck region so that it could support the relatively larger heads characteristic of neoceratopsians (Hatcher et al., 1907).