Palpebral (bone)

The palpebral bone is a small dermal bone found in the region of the eye socket in a variety of animals, including crocodilians and ornithischian dinosaurs. In ornithischians, it can form a prong that projects from the front upper corner of the orbit. It is large in heterodontosaurids,basal ornithopods such as Thescelosaurus (as Bugenasaura) and Dryosaurus, and basal ceratopsians such as Archaeoceratops; in these animals, the prong is elongate and would have stuck out and over the eye like a bony eyebrow. As paleoartist Gregory S. Paul has noted, elongate palpebrals would have given their owners fierce-looking "eagle eyes". In such cases, the expanded palpebral may have functioned to shade the eye.

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