A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Campanian of Utah, North America

A new hadrosaurid is described from the Upper Cretaceous Neslen Formation of central Utah. <i>Rhinorex condrupus</i> gen. et sp. nov. is diagnosed on the basis of two unique traits, a hook-shaped projection of the nasal anteroventral process and dorsal projection of the posteroventral process of the premaxilla, and is further differentiated from other hadrosaurid species based on the morphology of the nasal (large nasal boss on the posterodorsal corner of the circumnarial fossa, small protuberences on the anterior process, absence of nasal arch), jugal (vertical postorbital process), postorbital (high degree of flexion present on posterior process), and squamosal (inclined anterolateral processes). This new taxon was discovered in estuarine sediments dated at approximately 75 Ma and just 250 km north of the prolific dinosaur-bearing strata of the Kaiparowits Formation, possibly overlapping in time with <i>Gryposaurus monumentensis</i>. Phylogenetic parsimony and Bayesian analyses associate this new taxon with the <i>Gryposaurus</i> clade, even though the type specimen does not possess the diagnostic nasal hump of the latter genus. Comparisons with phylogenetic analyses from other studies show that a current consensus exists between the general structure of the hadrosaurid evolutionary tree, but on closer examination there is little agreement among species relationships.http://zoobank.org/urn:lsid:zoobank.org:pub:0FDD0FE6-6C20-4838-BD4A-092161179095

研究描述了产自美国犹他州中部上白垩统内斯伦组（Neslen Formation）的一新鸭嘴龙科（Hadrosauridae）物种。鼻吻龙（*Rhinorex condrupus*）gen. et sp. nov.（新属新种）基于两处独有特征确立分类鉴别依据：鼻骨前腹突的钩状突起与前上颌骨后腹突的背侧突起；此外还可通过以下骨骼形态特征与其他鸭嘴龙科物种相区分：鼻骨（环绕鼻窝后背角处具大型鼻骨隆突、前突具小型突起、无鼻骨拱）、颧骨（眶后突垂直）、眶后骨（后突高度弯曲）以及鳞骨（前外侧突倾斜）。该新分类单元发现于约75 Ma的河口沉积地层中，其地理位置位于盛产恐龙化石的凯帕罗维茨组（Kaiparowits Formation）地层以北仅250公里处，生存时间可能与纪念碑怪鼻龙（*Gryposaurus monumentensis*）存在重叠。系统发育简约分析与贝叶斯分析均显示，该新分类单元隶属于怪鼻龙属（*Gryposaurus*）演化支，尽管其正模标本不具备该属的鉴别性鼻骨隆突。与其他研究的系统发育分析对比后可见，当前鸭嘴龙科演化树的整体框架已达成一定共识，但深入分析后发现，各物种间的演化关系仍存在较大分歧。http://zoobank.org/urn:lsid:zoobank.org:pub:0FDD0FE6-6C20-4838-BD4A-092161179095