Data from: Comparative cranial myology and biomechanics of Plateosaurus and Camarasaurus and evolution of the sauropod feeding apparatus

Sauropodomorpha represents an important group of Mesozoic megaherbivores, and includes the largest terrestrial animals ever known. It was the first dinosaur group to become abundant and widespread, and its members formed a significant component of terrestrial ecosystems from the Late Triassic until the end of the Cretaceous. Both of these factors have been explained by their adoption of herbivory, but understanding the evolution of sauropodomorph feeding has been hampered by the scarcity of biomechanical studies. To address this, the jaw adductor musculature of the basal sauropodomorph Plateosaurus and the sauropod Camarasaurus have been reconstructed. These reconstructions provide boundary conditions for finite element models to assess differences in structural performance between the two taxa. Results demonstrate that Camarasaurus was capable of much greater bite forces than Plateosaurus, due to greater relative adductor muscle mass and shape changes to the mandible. The skull and mandible of Camarasaurus are also ‘stronger’ under static biting. The Plateosaurus mandible appears to compromise structural efficiency and force transmission in order to maintain relatively high jaw closure speed. This supports suggestions of facultative omnivory in basal sauropodomorph taxa. The expanded mandibular symphysis and ‘lateral plates’ of sauropods each lead to greater overall craniomandibular robustness, and may have been especially important in accommodating forces related to asymmetric loading. The functional roles of these characters, and observed general shape changes in increasing skull robustness, are consistent with hypotheses linking bulk-herbivory with the origin of Sauropoda and the evolution of gigantism.蜥脚形亚目（Sauropodomorpha）是中生代一类重要的巨型植食性恐龙类群，包含了迄今已知体型最为庞大的陆生动物。该类群是首个实现繁盛与广泛分布的恐龙支系，其成员自三叠纪晚期直至白垩纪末期，始终构成陆地生态系统的核心组成部分。此前学界多将这两大演化特征归因于其植食性习性的建立，但对蜥脚形亚目进食机制演化的理解长期受限于生物力学研究的匮乏。为填补这一研究空白，本研究对基干蜥脚形亚目板龙（Plateosaurus）以及蜥脚类圆顶龙（Camarasaurus）的下颌收肌进行了三维重建。上述重建结果可为有限元模型（finite element models）提供边界条件，用以评估二者在结构性能上的差异。研究结果表明，圆顶龙的咬合力远高于板龙，这一差异源于其相对更大的收肌质量与下颌骨的形态改造；同时，圆顶龙的颅骨与下颌骨在静态咬合工况下也具备更优的结构强度。板龙的下颌骨则在结构效率与力传递效率上做出了一定妥协，以维持相对较高的下颌闭合速度，这一发现支持了基干蜥脚形亚目类群具备兼性杂食性的相关学术假说。蜥脚类所特有的扩大下颌联合与"侧侧板"结构，分别提升了整体颅下颌系统的坚固性，这可能在应对不对称加载相关的受力时发挥了尤为关键的作用。上述特征的功能角色，以及颅骨坚固性随演化进程逐步提升的普遍趋势，均与"大量植食性习性与蜥脚类起源及巨型化演化存在关联"的假说相一致。