Hadrosaurus breviceps Marsh, 1889

Prieto-Márquez, Albert, Weishampel, David B. & Horner, John R., 2006, The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus, Acta Palaeontologica Polonica 51 (1), pp. 77-98 : 93

Hadrosaurus breviceps Marsh, 1889

Holotype: YPM 1779 , a partial dentary.

Type locality: Bearpaw Mountain , Yellowstone, Wyoming .

Type horizon: Judith River Formation, Campanian, Upper Cretaceous.

Comments.—This species was briefly described and figured by Marsh in two short papers in 1889 and 1890. Lull and Wright (1942) considered this material to be a species of Kritosaurus as K. breviceps . YPM 1779 consists of the middle to caudal part of the main body of a dentary ( Fig. 6D). Caudally, the specimen includes nearly the last teeth of the dental battery and the rostrodorsal portion of the mandibular canal. The ventral portion of the dentary is eroded away. The dentary is relatively wide mediolaterally. There are 27 tooth positions and a maximum of two teeth contributing to the occlusal plane per each position. Tooth crowns are dorsoventrally elongate, with a ratio of crown length/width of 3.1 to 3.4 ( Fig. 6D 2 ). The occlusal plane is flat, in contrast to the concave condition observed in M. peeblesorum , B. canadensis , Gryposaurus , and Edmontosaurus ( Ostrom 1961; Weishampel 1984).

Conclusion.— H. breviceps is a nomen dubium due to the lack of distinguishable characters; referrable to Hadrosauridae indeterminate.

Figures

Fig. 2. Hadrosaurus foulkii Leidy, 1858 (ANSP 10005), Haddonfield, New Jersey, U.S.A., Wood− bury Formation, Campanian, Upper Cretaceous. A. Left radius in dorsal view. B. Left ulna in medial view . C. Left humerus in anteromedial view. D. Partial left coracoid in glenoidal (D1) and craniolateral (D2) views. E. Schematic drawing of a generalized hadrosaurid coracoid showing in white the preserved region displayed in D.