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Poster Session Abstracts: Taxonomic Diagnosis of the Hadrosaur from the Liscomb Bone Bed, Prince Creek Formation, North Slope, Alaska - Abstract
Several taxa of Ornithischian dinosaurs have been collected from the Liscomb Bone Bed, Prince Creek Formation, North Slope, Alaska, including the hadrosaur believed to be Edmontosaurus. The available fossils were collected from the Liscomb bone bed in the cliffs overlooking the Colville River by University of California Berkeley and University of Alaska investigators. All the skull materials collected belong to juveniles. Because juveniles experience significant morphological changes related to ontogeny, a diagnosis to the species is intangible. A new taxonomic examination of fossils from the University of Alaska Fairbanks Museum of The North's collection was preformed to ascertain the identity of the North Slope hadrosaur. The examined specimens are here diagnosed as c.f. Edmontosaurus based on (1) the jugal being massive relative to other hadrosaurines; (2) the frontals being longer than wide irregular shaped and flat; (2) the body of the postorbital is enlarged, and deeply excavated on the orbital surface relative to other hadrosaurines; (3) the orbit is large; (4) squamosals do not make contact along the dorsal midline; (5) a caudal extension of the circum-naril depression exists above the rostral margin of the orbit; (6) the mandible is robust and the dentary accounts for more than 75% of the mandibular length, a trait not shared by other hadrosaurines; (7) rostral region of the mandible is edentulous and elongated relative to other hadrosaurines; (8) skull is high and broad posteriorly; (9) and the skull is triangular is shape when viewed from the side. Due to the lack of adult skull material, it is suggested that the new taxonomic diagnosis of c.f. Edmontosaurus is most appropriate. It is further suggested that this diagnosis stand until adult skull material is found.
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