A new taxon, Cymbospondylus duelferi sp. nov., is described from the late Anisian of the Fossil Hill Member of the Favret Formation of the Augusta Mountains, Pershing County, Nevada, USA. The holotype and only specimen consists of a fairly complete skull associated with articulated and disarticulated postcranial material. Body length reconstruction revealed a medium-sized individual with an estimated body length of 4.3 m. Dorsal vertebrae as well as the left humerus of this specimen are associated with three strings of articulated tail and posterior dorsal vertebrae, which are on average 68% smaller than the vertebrae of the medium-sized individual. Due to the small size of these vertebrae and their position within the trunk region, they most likely represent fetuses. Cymbospondylus duelferi sp. nov. provides the second-oldest evidence for viviparity in ichthyosaurs. In the course of this study, the skull morphology of C. petrinus and C. nichollsi was reviewed, resulting in revised character scorings for both. Phylogenetic analyses demonstrate a sister-taxon relationship of the new taxon with C. petrinus, which was found in the same stratigraphic unit, the Fossil Hill Member, that also crops out at the classical Fossil Hill locality in the Humboldt Range, where the member is part of the Prida Formation. Cymbospondylus duelferi sp. nov. shares a very similar skull morphology with C. petrinus and C. nichollsi, whereas the shoulder girdle morphology differs. Because there is no evidence for ontogenetic differences or sexual dimorphism in the new specimen, a third species of Cymbospondylus – neglecting the type species C. piscosus that is only known from five vertebrae – is recognized from the Fossil Hill Member. Further occurrences of the genus in the Lower and Middle Triassic of Svalbard (Boreal Ocean) and Europe (Tethys) point to a very fast radiation and dispersal of cymbospondylids during the Middle Triassic.

https://zoobank.org:pub:906F5F32-9090-496D-8FC7-680D25EED5EF

一个新的分类单元，Cymbospondylus duelferi sp。nov。，是从美国内华达州潘兴县奥古斯塔山脉Favret组化石山成员的晚期Anisian来描述的。完整的且唯一的标本由一个相当完整的颅骨与颅骨的关节连接和脱关节的材料组成。体长重建显示一个中等身材的个体，估计体长为4.3 m。该标本的背椎和左肱骨与三节铰接的尾巴和后背椎骨相连，平均比中型个体的椎骨小68％。由于这些椎骨的尺寸较小，并且它们在躯干区域内的位置，它们很可能代表胎儿。小叶锦蛇sp。十一月 提供了鱼龙活胎的第二大证据。在这项研究的过程中，对C. petrinus和C. nichollsi的头骨形态进行了审查，从而对这两种字符的得分进行了修改。系统发育分析表明，新的分类单元与小孢子虫（C. petrinus）之间存在姐妹-分类单元关系，这是在同一地层​​单元Fossil Hill Member中发现的，该单元也出现在洪堡山脉（Humboldt Range）的经典Fossil Hill位置，该成员位于Prida编队的一部分。杯椎鱼龙duelferi SP。十一月 与C. petrinus和C. nichollsi有着非常相似的头骨形态，而肩带的形态有所不同。由于没有证据表明新标本中存在个体差异或性别二态性，因此从化石山成员那里可以识别出第三种斜纹夜蛾（Cymbospondylus），它忽略了仅从五个椎骨得知的粘液梭状芽胞杆菌（C. piscosus）。斯瓦尔巴特群岛（北海）和欧洲（特提斯）在三叠纪的中下三叠纪进一步发生，这表明三叠纪中的三角棘皮非常快速地辐射和扩散。

https://zoobank.org:pub:906F5F32-9090-496D-8FC7-680D25EED5EF