Mud to muscles: Dinosaur-bird locomotor evolution from fossil footprints

化石足迹是一种直接的运动记录，而骨骼是永远无法做到的。我将用化石足迹来探索鸟类从兽脚亚目恐龙进化而来时所发生的运动变化。与它们的恐龙祖先相比，鸟类的尾巴和相关的肌肉组织都要小得多。鸟类为了飞行而“放弃”了陆地运动的优势吗？化石足迹记录中是否记录了肢体运动的进化变化？如果是这样的话，它们是从尾巴驱动的兽脚亚目恐龙逐渐转变为膝盖驱动的鸟类，还是随着特定特征的出现，肢体运动突然发生了变化？从泥到肌肉，我将结合联合收割机先进的3D成像，物理实验和计算机模拟来弥合化石足迹和化石骨骼之间现有的差距，揭示这一重要的进化转变。基于实验室的足迹制作实验将结合联合收割机运动学和动力学分析，以建立一个前所未有的足迹形成的观点。将使用化石足迹重建长期灭绝的恐龙的肢体运动，然后将使用超级计算机模拟模拟每一粒沉积物对缩进的脚的反应来测试重建的运动。这些模拟将计算脚和地面之间发生的力。这些力量和运动将驱动肌肉骨骼生物力学模拟，不仅可以揭示恐龙的脚在做什么，还可以揭示这些神秘动物的整个四肢甚至身体曾经是如何运动的。通过从世界各地采集自兽脚亚目恐龙首次出现以来的2.3亿年的化石足迹样本，该项目将恢复沿着鸟类谱系的运动轨迹。使用严格的，创新的方法，我的建议将解锁灭绝动物移动方式的定量分析，促进与现存后代的直接比较，并提供无法单独从骨骼恢复的运动进化的独特视角。

Fossil footprints are a direct record of motion in a way that skeletons can never be. I will use fossil footprints to explore the locomotor changes that took place as birds evolved from theropod dinosaurs. Compared to their dinosaur ancestors, birds have a much-reduced tail and associated musculature. Did birds "give up" terrestrial locomotor superiority in order to fly? Are evolutionary changes in limb motions recorded in the fossil footprint record? If so, do they show a gradual change from tail-driven theropods to knee-driven birds, or do limb motions change abruptly with the appearance of specific traits?From mud to muscles, I will combine advanced 3D imaging, physical experimentation, and computer simulation to bridge the existing gap between fossil footprints and fossil skeletons, shedding light on this important evolutionary transition. Lab-based footprint-making experiments will combine kinematic and kinetic analyses to build an unprecedented view of footprint formation. Limb motions of long-extinct dinosaurs will be reconstructed using fossil tracks, then supercomputer simulations modelling every grain of a sediment responding to the indenting foot will be used to test the reconstructed motions. These simulations will compute the forces occurring between foot and ground. These forces and motions will drive musculoskeletal biomechanical simulations that will shed light, not only on what the feet of dinosaurs were doing, but on how the whole limbs and even bodies of these enigmatic animals once moved.By sampling fossil tracks from around the world, spanning the 230 million years since theropods first appeared, this project will recover fossilised motions along the dinosaur-bird lineage. Using rigorous, innovative methods, my proposal will unlock quantitative analysis of the way extinct animals moved, facilitating direct comparison with their extant descendants, and providing a unique view of locomotor evolution that cannot be recovered from bones alone.