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.

发现于英国克罗姆霍尔采石场裂隙沉积中的晚三叠世（Late Triassic）喙头类（rhynchocephalian）宽齿克莱沃斯龙（Clevosaurus latidens Fraser, 1993），此前多项研究对其归入克莱沃斯龙属（Clevosaurus）的分类处理提出了质疑，部分系统发育分析（phylogenetic analyses）显示其与植食性喙头类亲缘关系密切。本研究重新检视了宽齿克莱沃斯龙的正模标本（type specimens）及归入标本，以阐明其分类学身份。此外，我们采用简约法（parsimony）与贝叶斯法（Bayesian）两种分析框架，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类系统发育分析结果均表明，宽齿克莱沃斯龙不应归入克莱沃斯龙属，而应代表一个全新的属。我们对该类群进行重新评估，并为弗雷泽楔齿龙新属（Fraserosphenodon gen. nov.）提供了修订后的鉴别特征。简约法与贝叶斯法分析得到的系统发育拓扑结构相似，我们还为喙头目内的两个高级演化支（clade）正式命名：真楔齿蜥演化支（Eusphenodontia）与新楔齿蜥演化支（Neosphenodontia）。