Data from: The Middle Triassic procolophonid Kapes bentoni: computed tomography of the skull and skeleton

Procolophonids were diverse small reptiles through the Late Permian and Triassic. Relatively complete specimens of various taxa are known from the Early and Late Triassic, but the ten or so Middle Triassic taxa, from South Africa, Russia, China and the UK, are mostly incomplete, being known only from skulls or partial and poorly preserved isolated elements. Because of their small size, it has often been difficult to establish details of anatomy using physical preparation methods, so application of scanning technology can massively improve knowledge. Here we describe the first substantial portion of a skull and anterior postcranial skeleton of the genus Kapes, known from Russia and the UK. CT scanning and 3D digital restoration of the new specimen from the Anisian Otter Sandstone of Devon, UK, reveal anatomical details previously unknown for this taxon, most notably the enlarged quadratojugal processes. This is also one of the few mature procolophonid specimens with a preserved postcranium, and it gives a valuable insight into ossification patterns. Fused sutures of the skull, fused scapulocoracoid, and heavily worn teeth show evidence of the common reptilian ossification pattern with a possible limitation in tooth replacement. There is sufficient anatomical information to include Kapes bentoni for the first time in a cladistic analysis, which shows that it is sister to the Russian Kapes majmesculae and part of a clade of Anisian taxa phylogenetically more basal than Procolophon. Inferences on the function of the quadratojugal spines and fossorial mode of life are also considered.

前棱蜥科（Procolophonidae）是晚二叠世至三叠纪时期多样性丰富的小型爬行动物类群。目前学界已在早三叠世与晚三叠世地层中发现多个类群的相对完整标本，但产自南非、俄罗斯、中国与英国的十余种中三叠世前棱蜥类，大多仅保存头骨或零散且保存不佳的孤立遗骸，完整性较差。由于其体型小巧，传统物理制备手段难以获取其解剖学细节，因此扫描技术的应用可极大提升该类群的研究认知。本文记述了产自俄罗斯与英国的凯佩斯龙属（Kapes）首个较为完整的头骨及前部颅后骨骼标本。对产自英国德文郡安尼阶奥特尔砂岩组的新标本进行CT扫描与三维数字化修复后，揭示了该类群此前未被知晓的解剖学特征，其中最显著的为其膨大的方轭突（quadratojugal processes）。该标本也是少数保存有颅后骨骼的成熟前棱蜥类标本之一，可为骨化模式研究提供重要参考。其头骨骨缝愈合、肩胛骨乌喙骨（scapulocoracoid）愈合以及牙齿重度磨损的特征，均符合常见爬行动物的骨化模式，且可能存在牙齿替换受限的情况。此次获取的充足解剖学信息，首次使得弯顿凯佩斯龙（Kapes bentoni）可被纳入分支系统学分析，结果显示其与俄罗斯的马伊梅斯库拉凯佩斯龙（Kapes majmesculae）互为姐妹群，且属于安尼阶类群组成的演化支，系统发育位置较前棱蜥属（Procolophon）更为基干。本文还探讨了其方轭棘突（quadratojugal spines）的功能以及该类群可能的穴居生活方式。