A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Upper Cretaceous of Shandong, China

Abstract

A new saurolophine hadrosaurid, Laiyangosaurus youngi gen. et sp. nov. is described and phylogenetically analyzed based on several cranial elements from the Jingangkou Formation, Wangshi Group, Upper Cretaceous of Laiyang, Shandong, China. Laiyangosaurus youngi differs from other members of the saurolophine clade on the basis of a number of autapomorphies, including a prominent and narrow ridge on the lateral side of the nasal which forms the posterodorsal and posterior margin of the circumnasal depression, a primary ridge that runs along most of the maxillary tooth row that is slightly deflected posteriorly, a retroarticular process of the surangular that is dorsolateroposteriorlly recurved, and orbital margins that are wider than the infratemporal margins of the jugal. This new taxon can be further distinguished by a number of unique combination of characters, including dorsal margin of nasal is flat, absence supracranial crest, a relatively shallow and rostrodorsally directed caudal margin of the lacrimal process of the jugal, and one or more foramina present on the rostral surface of the premaxilla. A phylogenetic analysis indicates that L. youngi comprises a monophyletic clade, which is known as Edmontosaurini.