Wiktionary
n. An extension to the dentary in the jawbone of some dinosaurs
Wikipedia
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.
Usage examples of "predentary".
Among them, for example, are the presence of a toothless bone called a predentary at the frdnt of the lower jaw and a toothless forward end of the upper jaw.
The roughened, external surface of the predentary and the front portion of the upper jaw are an indication of a once-present horny bill in front of the snout.