Data from: Herbivorous dinosaur jaw disparity and its relationship to extrinsic evolutionary drivers

Morphological responses of nonmammalian herbivores to external ecological drivers have not been quantified over extended timescales. Herbivorous nonavian dinosaurs are an ideal group to test for such responses, because they dominated terrestrial ecosystems for more than 155 Myr and included the largest herbivores that ever existed. The radiation of dinosaurs was punctuated by several ecologically important events, including extinctions at the Triassic/Jurassic (Tr/J) and Jurassic/Cretaceous (J/K) boundaries, the decline of cycadophytes, and the origin of angiosperms, all of which may have had profound consequences for herbivore communities. Here we present the first analysis of morphological and biomechanical disparity for sauropodomorph and ornithischian dinosaurs in order to investigate patterns of jaw shape and function through time. We find that morphological and biomechanical mandibular disparity are decoupled: mandibular shape disparity follows taxonomic diversity, with a steady increase through the Mesozoic. By contrast, biomechanical disparity builds to a peak in the Late Jurassic that corresponds to increased functional variation among sauropods. The reduction in biomechanical disparity following this peak coincides with the J/K extinction, the associated loss of sauropod and stegosaur diversity, and the decline of cycadophytes. We find no specific correspondence between biomechanical disparity and the proliferation of angiosperms. Continual ecological and functional replacement of pre-existing taxa accounts for disparity patterns through much of the Cretaceous, with the exception of several unique groups, such as psittacosaurids that are never replaced in their biomechanical or morphological profiles.非哺乳类植食动物对外部生态驱动因子的形态响应，尚未在长时间尺度下得到量化。植食性非鸟类恐龙是验证此类响应的理想类群，因为它们主导陆地生态系统长达1.55亿年，且包含了地球史上体型最大的植食动物。 恐龙的适应性辐射演化曾被多起生态关键事件打断，包括三叠纪/侏罗纪（Tr/J）与侏罗纪/白垩纪（J/K）界线处的灭绝事件、苏铁类植物的衰落，以及被子植物的起源——所有这些事件都可能对植食动物群落产生了深远影响。 本文首次针对蜥脚形亚目与鸟臀目恐龙开展形态与生物力学差异度（disparity）分析，以探究颌骨形态与功能随时间的演化模式。研究发现，下颌的形态差异度与生物力学差异度彼此解耦：下颌形状差异度随分类多样性变化，在中生代呈持续上升趋势。 与之形成对比的是，生物力学差异度在侏罗纪晚期达到峰值，这一峰值与蜥脚类恐龙间的功能多样性提升相吻合。该峰值之后的生物力学差异度下降，与J/K灭绝事件、伴随而来的蜥脚类与剑龙类多样性丧失，以及苏铁类植物的衰落恰好重合。 研究未发现生物力学差异度与被子植物扩张之间存在特定关联。在白垩纪的大部分时段，已有类群的持续生态与功能替代解释了差异度的变化模式，唯有鹦鹉嘴龙类等若干独特类群除外——这类群从未在功能或形态特征上被其他类群替代。