Gryposaurus incurvimanus (Parks, 1920)

Gates, Terry A. & Sampson, Scott D., 2007, A new species of Gryposaurus (Dinosauria: Hadrosauridae) from the late Campanian Kaiparowits Formation, southern Utah, USA, Zoological Journal of the Linnean Society 151 (2), pp. 351-376 : 353

GRYPOSAURUS INCURVIMANUS PARKS, 1919

Revised diagnosis: Hadrosaurids of the genus Gryposaurus possessing: dorsal premaxillary process that is more concave posteriorly than in other species of the genus; nasal arch smaller than in other species and positioned well anterior to the orbit and rising to a level below the frontals; jugal with a small spur on the posterior margin of the posteroventral flange; and slightly excavated ventral surface of the nasal hump. In addition, G. incurvimanus possesses the following unique combination of characters: nearly straight lateroventral margin of the maxilla; infratemporal fenestra larger than the orbit; and broad ‘U’-shaped posterior margin of the external naris. Gryposaurus incurvimanus is significantly more gracile than either G. notabilis or G. monumentensis . It has a smaller premaxillary lip than the other species, as well as premaxillae that are angled more steeply than in other species. Gryposaurus incurvimanus also possesses an anteroposteriorly shortened skull relative to the maximum skull depth.

Holotype: ROM 764 , mostly complete skull and complete postcranium.