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. It is also known as the adlacrimal[1] or supraorbital, although the latter term may not be confused with the supraorbital in osteichthyan fishes.[2] In ornithischians, the palpebral can form a prong that projects from the front upper corner of the orbit. It is large in heterodontosaurids,[3] basal ornithopods such as Thescelosaurus (as Bugenasaura) and Dryosaurus,[3] [4] and basal ceratopsians such as Archaeoceratops;[5] 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".[6] In such cases, the expanded palpebral may have functioned to shade the eye.[7]
. David B. Norman . Sues, Hans-Dieter . Witmer, Larry M. . Coria, Rodolfo A. . Weishampel, David B. . Dodson, Peter . Osmólska, Halszka . The Dinosauria . limited . 2nd . 2004. University of California Press . Berkeley . 978-0-520-24209-8 . 393–412 . Basal Ornithopoda.
. Gregory S. Paul . Paul, Gregory S. . The Scientific American Book of Dinosaurs . 2000 . St. Martin's Press . New York . 978-0-312-26226-6 . 102 . Restoring the Life Appearances of Dinosaurs .