Data from: Craniodental functional evolution in sauropodomorph dinosaurs

Sauropodomorpha included the largest known terrestrial vertebrates and was the first dinosaur clade to achieve a global distribution. This success is associated with their early adoption of herbivory, and sauropod gigantism has been hypothesized to be a specialization for bulk-feeding and obligate high-fiber herbivory. Here, we apply a combination of biomechanical character analysis and comparative phylogenetic methods with the aim of quantifying the evolutionary mechanics of the sauropodomorph feeding apparatus. We test for the role of convergence to common feeding function and divergence towards functional optima across sauropodomorph evolution, quantify the rate of evolution for functional characters and test for coincident evolutionary rate shifts in craniodental functional characters and body mass. Results identify a functional shift towards increased cranial robustness, increased bite force, and the onset of static occlusion at the base of the Sauropoda, consistent with a shift towards bulk-feeding. Trends towards similarity in functional characters are observed in Diplodocoidea and Titanosauriformes. However, these two clades retain significant craniodental functional differences and evidence for convergent adoption of a common ‘adaptive zone’ between them is weak. Modelling of craniodental character and body mass evolution demonstrates that these functional shifts were not correlated with evolutionary rate shifts. Instead, a significant correlation between body mass and characters related to bite force and cranial robustness suggest a correlated-progression evolutionary mode, with positive-feedback loops between body mass and dietary specializations fueling sauropod gigantism.

蜥脚形亚目（Sauropodomorpha）包含迄今已知体型最大的陆生脊椎动物，也是首个实现全球分布的恐龙演化支。这一演化成功与其早期采取植食性习性密切相关，而学界曾提出假说，认为蜥脚类巨型化是特化以适应批量取食与专性高纤维植食的结果。本研究结合生物力学特征分析与比较系统发育方法，旨在量化蜥脚形亚目进食器官的演化机制。我们检验了蜥脚形亚目演化过程中，类群趋同于共同进食功能与向功能最适值分化的模式，量化了功能特征的进化速率，并检测颅齿功能特征与体重是否存在同步的进化速率移位。研究结果显示，在蜥脚类（Sauropoda）基部类群中，出现了颅部强健度提升、咬合力增强以及静态咬合行为出现的功能转变，这与转向批量取食的适应性变化相一致。梁龙超科（Diplodocoidea）与泰坦龙形类（Titanosauriformes）中均观察到功能特征趋于相似的演化趋势，但这两个演化支仍保留了显著的颅齿功能差异，且二者之间趋同演化形成共同‘适应区’的证据较为薄弱。对颅齿特征与体重演化的建模分析表明，上述功能转变并未与进化速率移位存在相关性。相反，体重与咬合力、颅部强健度相关特征之间存在显著相关性，这提示二者遵循协同进化模式——体重与食性特化之间的正反馈循环，推动了蜥脚类巨型化的演化进程。