Predentary

The predentary is an ossification situated on the front of the lower jaw, which extended the dentary (the main lower jaw bone). It is found in the fossilised remains of ornithischian dinosaurs, which were herbivorous. The predentary coincided with the premaxilla in the upper jaw. Together, they formed a beak-like apparatus used to clip off plant material. In ceratopsian dinosaurs, it opposes the rostral bone.