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.

与俄罗斯、南非相比，中国的帕拉蜥类（pareiasaur）化石记录较为匮乏。本文报道了一件产自中国内蒙古大青山地区上二叠统脑包沟组的帕拉蜥类新标本，该标本被归入埃尔金龙属（Elginia）的一个新物种，该属此前仅在苏格兰上二叠统卡蒂希尔砂岩组中有化石记录。该物种的鉴别特征包括：中等发育的颊突（cheek flange）；显著的耳凹（otic notch，由颞板（temporal plate）后缘的鳞骨（squamosal）与方轭骨（quadratojugal）共同围成）；前额骨（prefrontal）、后额骨（postfrontal）及眶后骨（postorbital）上的眶上隆起（supraorbital bosses）明显增大；上颞角（supratemporal horn）极度膨大，鳞骨角（squamosal horn）自颞板的后缘（caudal margin）显著向后突出。该新类群与奇异埃尔金龙（E. mirabilis）的区别在于：具有发育良好、呈新月形的后额骨隆起，该隆起为一系列眶周隆起（circumorbital bosses）中最大的一个；眶上缘（upper orbital border）明显呈穹隆状，前背缘（anterodorsal margin）平滑而非棱角状；颅顶隆起（cranial bosses）发育较弱；部分背椎（dorsal vertebrae）的横突（transverse process）与后关节突（postzygapophysis）基部愈合，形成水平突缘（horizontal flange）。此次新发现极大地拓展了埃尔金龙属（Elginia）及埃尔金龙科（Elginiidae）的地理分布范围。