Data from: The tetrapod fauna of the upper Permian Naobaogou Formation of China: a new species of Elginia (Parareptilia, Pareiasauria)

The pareiasaur fossil record in China is poor compared to that of Russia or South Africa. A new pareiasaur specimen is here reported from the upper Permian Naobaogou Formation of the Daqing Mountains, Nei Mongol, China. It is recognized as a new species of Elginia, a taxon otherwise known only from the upper Permian Cutties Hillock Sandstone of Scotland. Diagnostic features include a moderately developed cheek flange; prominent otic notch (formed between squamosal and quadratojugal at the posterior margin of the temporal plate); enlarged supraorbital bosses on prefrontal, postfrontal, and postorbital; a hypertrophied supratemporal horn, and squamosal horn prominently projecting posteriorly from caudal margin of temporal plate. The new taxon is differentiated from E. mirabilis by a well-developed and crescentic postfrontal boss, which is the largest among a series of circumorbital bosses; upper orbital border distinctly domed with a smooth rather than angled anterodorsal margin; lesser developed cranial bosses, basal confluence of the transverse process and postzygapophysis produces at horizontal flange in some dorsal vertebrae. The new discovery significantly extends the geographic distribution of Elginia and Elginiidae.

相较于俄罗斯与南非，中国的pareiasaur（盾甲龙类）化石记录较为匮乏。本次研究报道了一件采自中国内蒙古大青山地区晚二叠世脑包沟组的盾甲龙类新标本。该标本被归入Elginia（埃尔金龙属）的一个新物种，此前该属仅发现于苏格兰晚二叠世卡蒂希尔砂岩组地层中。该新物种的鉴定特征如下：发育中等的颊缘突；显著的耳凹（由颞板后缘的鳞骨与方轭骨共同围合而成）；前额骨、后额骨及眶后骨均具膨大的眶上隆脊；极度膨大的上颞角，以及从颞板后缘显著向后突出的鳞骨角。该新分类群与E. mirabilis（奇异埃尔金龙）的区别在于：其发育完好且呈新月形的后额骨隆脊为一系列眶周隆脊中最大的；眶上缘呈显著穹隆状，前背缘光滑圆润而非棱角分明；颅顶隆脊发育较弱；部分背椎的横突与后关节突在基部愈合，形成水平翼状结构。此次新发现极大地拓展了Elginia（埃尔金龙属）以及Elginiidae（埃尔金龙科）的地理分布范围。