The cerapods (Cerapoda, or “horn-footed”) were the group within the Neornithischia—a sister group of the Thyreophora within the clade Genasauria. They are divided into the ornithopods (Ornithopoda; “bird-foot”) and marginocephalians (Marginocephalia; “fringed-heads”); other classifications divide the Marginocephalia into two groups: the Pachycephalosauria (“thick-headed lizards”) and Ceratopsia (“horned-face”). In general, the primary characteristic of the cerapods was that they had only five or fewer premaxillary teeth, with the enamel distributed differently on the sides of their teeth. The Marginocephalia are often distinguished by a bony shelf they had at the back of the skull. One example is the Stormbergia dinosaur fossil from the Early Jurassic period in South Africa.