Quantifying the gastral mass in Early Cretaceous ornithuromorphs (Aves: Ornithothoraces) from the Jehol avifauna

Some birds intentionally ingest stones to facilitate digestion of hard foodstuffs, a behavior inherited from non-avian dinosaurs and present in some of the earliest birds, as evidenced from clusters of gastroliths preserved within the abdominal cavity of a wide range of dinosaurs and Cretaceous birds. For the first time, high-resolution computed laminographic and computed tomographic scans were used to reconstruct the gastral mass in two species of non-neornithine ornithuromorph birds from the Lower Cretaceous Jehol Group. Four specimens of each taxon were analyzed. Preservation of the gastral mass in most of these specimens is in situ and regarded as complete or nearly so. The number of gastroliths, their total volume, and their total mass relative to the estimated body mass were calculated for each specimen. The resultant gastral mass-to-body mass ratios fall within the range observed in extant birds, supporting previous inferences that the digestive system in non-neornithine ornithur..., Eight ornithuromorph individuals were scanned by computed tomographic (CT) or computed laminographic (CL). After scanning, all data were processed and rendered using the software VG Studio 3.4. Lastly, all related parameters were extracted in VG Studio 3.4 and processed in Microsoft Excel. R was used to demonstrate that all data fell within the confidence interval. ,部分鸟类会主动吞食石块以辅助硬质食物的消化，这一行为继承自非鸟类恐龙，且在部分早期鸟类中亦有发现，相关证据来自广泛类群的恐龙与白垩纪鸟类腹腔内保存的胃石（gastroliths）集群。本研究首次采用高分辨率层叠计算机断层扫描（computed laminographic, CL）与计算机断层扫描（computed tomographic, CT）技术，对下白垩统热河群中两种非新鸟亚纲今鸟型类的胃石团进行三维重建。每个类群共分析4件标本，多数标本中的胃石团保存状态为原位保存，且被认定为完整或近乎完整。针对每件标本，研究人员计算了胃石的数量、总容积，以及相对于估算体重的总质量。所得胃石团质量与体重之比落在现生鸟类的观测范围内，这支持了此前关于非新鸟亚纲今鸟型类消化系统的推论……（原文此处存在截断）。本次研究共对8件今鸟型类个体开展了CT或CL扫描，扫描完成后，所有数据均通过VG Studio 3.4软件进行处理与可视化渲染。随后，研究人员在VG Studio 3.4中提取全部相关参数，并使用Microsoft Excel完成数据整理，最终通过R语言验证所有数据均落在置信区间内。