Data from: Taxonomic reassessment of Clevosaurus latidens Fraser, 1993 (Lepidosauria, Rhynchocephalia) and rhynchocephalian phylogeny based on parsimony and Bayesian inference

The Late Triassic rhynchocephalian Clevosaurus latidens Fraser, 1993 is known from the fissure deposits of Cromhall Quarry, England. Many studies have questioned its referral to the genus Clevosaurus and some phylogenetic analyses suggest a close relationship with herbivorous rhynchocephalians. We reexamine the type specimens and referred material of C. latidens to elucidate its taxonomic identity. Additionally, we provide new phylogenetic analyses of the Rhynchocephalia using both parsimony and Bayesian approaches. Our taxonomic review and both phylogenetic analyses reveal that C. latidens is not referable to Clevosaurus, but represents a new genus. We reassess C. latidens and provide an amended diagnosis for the new genus Fraserosphenodon gen. nov. Both parsimony and Bayesian analyses recover similar topologies and we propose formal names for two higher clades within Rhynchocephalia: Eusphenodontia and Neosphenodontia.

1993年Fraser命名的宽齿克卢氏喙头龙（Clevosaurus latidens Fraser, 1993）是一类三叠纪晚期的喙头类（rhynchocephalian）动物，其化石发现于英国克罗霍尔采石场的裂隙堆积地层中。此前诸多研究对其归入克卢氏喙头龙属（Clevosaurus）的分类学归属提出了质疑，部分系统发育分析显示该物种与植食性喙头类类群存在密切的亲缘关系。本研究重新检视了宽齿克卢氏喙头龙的正型标本及归入该物种的相关材料，以阐明其分类学身份。此外，本研究分别采用简约法（parsimony）与贝叶斯（Bayesian）分析法，针对喙头目（Rhynchocephalia）开展了全新的系统发育分析。本次分类学梳理与两项系统发育分析结果均表明，宽齿克卢氏喙头龙并不隶属于克卢氏喙头龙属，而是代表一个全新的属。本研究重新评估了该物种，并为这个新属弗雷泽喙头龙属（Fraserosphenodon gen. nov.）提供了修订后的鉴别诊断特征。简约法与贝叶斯分析得到的拓扑结构高度一致，本研究还为喙头目下的两个高阶演化支正式命名为真楔齿类（Eusphenodontia）与新楔齿类（Neosphenodontia）。