Zhang Jialiang, Wang Xiaolin, Wang Qiang, Jiang Shunxing, Cheng Xin, Li Ning, Qiu Rui
Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing, 100044, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
An Acad Bras Cienc. 2019;91Suppl 2(Suppl 2):e20160920. doi: 10.1590/0001-3765201720160920. Epub 2017 Aug 31.
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.
一种新的亚冠龙类鸭嘴龙，杨氏莱阳龙（Laiyangosaurus youngi）属种，根据来自中国山东莱阳上白垩统王氏群金刚口组的几块颅骨化石进行了描述和系统发育分析。杨氏莱阳龙与亚冠龙类分支的其他成员不同，具有一些独征，包括鼻骨外侧突出且狭窄的嵴，形成鼻周凹陷的后上缘和后缘；一条沿着大部分上颌齿列延伸且略向后偏转的主嵴；隅骨的关节后突向背外侧后弯；眶缘比颧骨的颞下边缘宽。这个新分类单元还可以通过一些独特的特征组合进一步区分，包括鼻骨的背缘平坦，无颅顶嵴；颧骨泪突的尾缘相对较浅且向前背侧方向；以及前上颌骨的吻面有一个或多个孔。系统发育分析表明，杨氏莱阳龙构成一个单系类群，即埃德蒙托龙类。
