ABSTRACT Three-dimensional Late Cretaceous elasmobranch endoskeletal elements (including palatoquadrates, ceratohyals, braincase fragments, and a series of anterior vertebrae) are described from the Late Cretaceous University of Alabama Harrell Station Paleontological Site (HSPS), Dallas County, Alabama. The material is referred to the extant elasmobranch Family Squatinidae on the basis of several distinctive morphological features. It also exhibits features not shared by any modern or fossil Squatina species or the extinct Late Jurassic squatinid Pseudorhina. A new genus and species is erected, despite there being some uncertainty regarding potential synonymy with existing nominal species previously founded on isolated fossil teeth (curiously, no squatinid teeth have been documented from the HSPS). A preliminary phylogenetic analysis suggests that the new genus falls on the squatinid stem, phylogenetically closer to Squatina than Pseudorhina. The craniovertebral articulation in the new genus exhibits features considered convergent with modern batomorphs (skates and rays), including absence of contact between the posterior basicranium and first vertebral centrum, and a notochordal canal which fails to reach the parachordal basicranium. Supporting evidence that similarities in the craniovertebral articulation of squatinoids and batomorphs are convergent rather than synapomorphic (as “hypnosqualeans”) is presented by an undescribed Early Jurassic batomorph, in which an occipital hemicentrum articulates with the first vertebral centrum as in all modern sharklike (selachimorph) elasmobranchs. The fossil suggests instead that the batomorph synarcual evolved by fusion of the anterior basiventral and basidorsal cartilages prior to the reduction of the anterior centra and loss of the occipital hemicentrum, not afterward as predicted by the hypnosqualean hypothesis.

中文翻译：

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晚白垩世天使鲨（Elasmobranchii；Squatinidae）的一个新属，以及对Squatinid系统发育的评论

摘要 阿拉巴马州达拉斯县晚白垩世大学哈雷尔站古生物遗址 (HSPS) 描述了晚白垩世的三维晚白垩世 elasmobranch 内骨骼元素（包括腭方、角状体、脑壳碎片和一系列前椎骨）。根据几种独特的形态特征，该材料被称为现存的 elasmobranch Family Squatinidae。它还展示了任何现代或化石 Squatina 物种或已灭绝的晚侏罗世 Squatinid Pseudorhina 所没有的特征。尽管与先前建立在孤立的化石牙齿上的现有名义物种的潜在同义词存在一些不确定性（奇怪的是，HSPS 中没有记录到扁平牙齿），但还是建立了一个新的属和种。初步的系统发育分析表明，新属落在鳞科植物的茎上，在系统发育上比 Pseudorhina 更接近 Squatina。新属的颅椎关节表现出被认为与现代蝙蝠形态（冰鞋和鳐鱼）融合的特征，包括后基颅骨和第一椎体之间没有接触，以及无法到达脊索基颅骨的脊索管。一个未描述的早侏罗纪 batomorph 提供了支持证据表明，squatinoids 和 batomorphs 的颅椎关节的相似性是会聚的而不是突触性的（如“hypnosqualeans”），其中一个枕骨半中心与所有现代鲨鱼类（selachi）一样与第一椎体连接。 ) 弹性分支。