Data_Sheet_1_Topology-Based Three-Dimensional Reconstruction of Delicate Skeletal Fossil Remains and the Quantification of Their Taphonomic Deformation.zip

Taphonomic and diagenetic processes inevitably distort the original skeletal morphology of fossil vertebrate remains. Key aspects of palaeobiological datasets may be directly impacted by such morphological deformation, such as taxonomic diagnoses and phylogenetic hypotheses, interpretations of the shape and orientation of anatomical structures, and assessments of interspecific and intraspecific variation. In order to overcome these ubiquitous challenges we present a novel reconstruction workflow combining retopology and retrodeformation, allowing the original morphology of both symmetrically and asymmetrically damaged areas of fossils to be reconstructed. As case studies, we present idealised three-dimensional reconstructions of the sternum of the crownward stem-bird Ichthyornis dispar, and cervical vertebrae of the diplodocid sauropod Galeamopus pabsti. Multiple Ichthyornis sterna were combined into a single, idealised composite representation through superimposition and alignment of retopologised models, and this composite was subsequently retrodeformed. The Galeamopus vertebrae were individually retrodeformed and symmetrised. Our workflow enabled us to quantify deformation of individual specimens with respect to our reconstructions, and to characterise global and local taphonomic deformation. Our workflow can be integrated with geometric morphometric approaches to enable quantitative morphological comparisons among multiple specimens, as well as quantitative interpolation of “mediotypes” of serially homologous elements such as missing vertebrae, haemal arches, or ribs.

古生物学中的埋藏学过程和成岩作用不可避免地扭曲了化石脊椎动物骨骼的原始形态。此类形态变形直接影响了古生物学数据集的关键方面，如分类诊断和系统发育假设、解剖结构形状和方向的解读，以及对种间和种内变异的评估。为了克服这些普遍存在的挑战，我们提出了一种新的重建工作流程，该流程结合了重拓扑和逆向变形技术，从而能够重建化石中对称和不对称受损区域的原始形态。作为案例研究，我们展示了伊卡蒂奥里斯（Ichthyornis dispar）胸骨和加莱阿摩普斯（Galeamopus pabsti） Diplodocid 长颈龙颈椎的理想化三维重建。通过重拓扑模型的叠加和对齐，将多个伊卡蒂奥里斯胸骨合并成一个单一的、理想化的复合表示，随后进行逆向变形。加莱阿摩普斯颈椎则分别进行逆向变形和对称化处理。我们的工作流程使我们能够量化单个标本相对于我们重建的变形，并表征全局和局部的埋藏学变形。我们的工作流程可以与几何形态测量方法相结合，以便在多个标本之间进行定量形态比较，以及定量插值连续同源元素（如缺失的椎骨、血拱或肋骨）的“中介型”。