Fabrosauridae

…consisted of several subgroups, including Fabrosauridae, Heterodontosauridae, Hypsilophodontidae, Iguanodontidae, and Hadrosauridae (the duck-billed dinosaurs). The fabrosaurs were the earliest and most primitive of the ornithopods; these small, lightly built dinosaurs reached lengths of 60–120 cm (2–4 feet). The heterodontosaurs began to develop the horny beaks and specialized teeth typical of…

In the fabrosaurids the teeth were simple leaf-shaped, laterally compressed elements arranged in a single front-to-back row in each jaw. They were not set in from the outer cheek surface as in most ornithopods. Small incisor-like teeth were borne on the premaxillary bones above, but (as always)…