Cranial anatomy of <i>Erlikosaurus andrewsi</i> (Dinosauria, Therizinosauria): new insights based on digital reconstruction

ABSTRACTThe skull of <i>Erlikosaurus andrewsi</i> from the Upper Cretaceous Baishin Tsav locality of Mongolia represents the only known three-dimensionally preserved and nearly complete skull of a therizinosaurian. Computed tomographic (CT) scanning of the original specimen and three-dimensional visualization techniques allow the cranial skeleton to be digitally prepared, disarticulated, and restored. Here, we present a detailed description of the restored skull morphology and the individual cranial elements, including visualization of the internal neurovascular and pneumatic structures. Information gained from this study is used in a revised and emended diagnosis for <i>E. andrewsi</i>. A reappraisal of the evolutionary and functional changes in the cranial skeleton as provided by this study supports prior proposals that a keratinous sheath or rhamphotheca was developed early in the evolution of Therizinosauria. Paralleled by the reduction of functional and replacement teeth, this development indicates a shift in the manner of food processing/procurement at the tip of the snout. Extensive pneumatization of the braincase, most evidently developed in <i>E. andrewsi</i> in comparison with other known therizinosaurians, appears to have led to a reduction of the adductor musculature and thus the potential bite force in derived therizinosaurians. In addition, the application of digital data, as presented in this study, introduces a novel way to document fossil data that will allow for morphological and anatomical data to be made widely accessible.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

摘要
产自蒙古国上白垩统白辛查干（Baishin Tsav）化石产地的安德鲁斯嗜蜥蜴龙（Erlikosaurus andrewsi）头骨，是目前已知唯一一件三维保存且近乎完整的镰刀龙类（therizinosaurian）头骨。本研究通过对原始标本开展计算机断层扫描（Computed Tomographic, CT）及三维可视化技术，实现了该颅部骨骼的数字化制备、解离与复原。本文详细描述了复原后的头骨形态及各颅部骨骼结构，其中涵盖内部神经血管与气腔构造的可视化呈现。本研究获取的相关信息被用于修订安德鲁斯嗜蜥蜴龙的鉴别特征。

通过本次研究对颅部骨骼演化与功能变化的重新评估，验证了此前提出的“镰刀龙类演化早期即已演化出角质鞘或喙鞘（rhamphotheca）”的学术观点。结合功能性牙齿与替换牙齿的退化现象，这一演化特征表明吻端的食物处理与获取方式发生了转变。相较于其他已知镰刀龙类，安德鲁斯嗜蜥蜴龙的脑壳具有极为显著的广泛气腔化构造，该特征似乎致使衍生型镰刀龙类的颌收肌发生退化，进而降低了其潜在咬合力。此外，本研究采用的数字化数据方法，为化石资料的记录提供了全新路径，可使形态学与解剖学数据实现广泛共享与获取。

补充数据——本文的补充材料可通过网址www.tandfonline.com/UJVP免费获取。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于Erlikosaurus andrewsi（一种镰刀龙类恐龙）的颅骨解剖，通过CT扫描和三维数字重建技术，提供了其颅骨形态、内部结构及演化功能的新见解。数据集包含原始和重建的3D PDF文件，支持了镰刀龙类早期角质鞘发展和颅骨气腔化对咬合力影响的研究，适用于古生物学、进化生物学和数字可视化领域。