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庞大的陆生动物。它是首个得以繁盛并广泛分布的恐龙类群，其成员自三叠纪晚期至白垩纪末期始终是陆地生态系统的重要组成部分。学界此前将这两项特征归因于该类群对植食性策略的采纳，但针对蜥脚形亚目取食行为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）的颌收肌群进行了重建。上述重建结果为有限元模型（finite element models）提供了边界条件，用以评估两个类群间的结构性能差异。研究结果显示，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以及下颌骨的形态变化。此外，圆顶龙的头骨与下颌骨在静态咬合状态下也具备更高的结构强度。板龙的下颌骨则在结构效率与力传递上做出了一定妥协，以此维持相对较高的颌骨闭合速度。该结果支持了基干蜥脚形亚目类群存在兼性杂食性的学术假说。蜥脚类所特有的扩张型下颌联合与侧骨板均能提升整体颅下颌坚固性，这或许在应对不对称载荷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，以及观测到的头骨坚固性随演化进程逐步提升的整体形态变化，均与"大规模植食策略与蜥脚类起源及体型巨型化演化存在关联"的假说相一致。