A study of wild Agama bibroni indicated that adults fed largely on Orthoptera with an active selection for species in the middle to large size range. The juvenile diet was mainly of Hymenoptera, Formicidae. This dietary difference led to a study of jaw mechanisms suggesting that due to a differential growth of the cranial bones, particularly those of the lower jaw, the mechanical advantages of the adult and juvenile jaws differed considerably. This allowed the rapid bite of the adult to be two and a half times more powerful, per unit area, than that of the juvenile. During slow close there was almost no difference in efficiency. From this it is suggested that the differing diets are not only the result of different habitats but also due to skeletal arrangements.