Locomotion has influenced the ecology, evolution, and extinction of species throughout history, yet studying locomotion in the fossil record is challenging. Computational biomechanics can provide novel insight by mechanistically relating observed anatomy to whole-animal function and behavior. Here, we leverage optimal control methods to generate the first fully predictive, three-dimensional, muscle-driven simulations of locomotion in an extinct terrestrial vertebrate, the bipedal non-avian theropod dinosaur Coelophysis. Unexpectedly, our simulations involved pronounced lateroflexion movements of the tail. Rather than just being a static counterbalance, simulations indicate that the tail played a crucial dynamic role, with lateroflexion acting as a passive, physics-based mechanism for regulating angular momentum and improving locomotor economy, analogous to the swinging arms of humans. We infer this mechanism to have existed in many other bipedal non-avian dinosaurs as well, and our methodology provides new avenues for exploring the functional diversity of dinosaur tails in the future.

中文翻译：

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跑步步态的预测模拟揭示了尾巴在双足恐龙运动中的关键动态作用

运动影响了整个历史上物种的生态、进化和灭绝，但研究化石记录中的运动具有挑战性。计算生物力学可以通过机械地将观察到的解剖结构与整个动物的功能和行为相关联来提供新的见解。在这里，我们利用最优控制方法来生成第一个完全预测的、三维的、肌肉驱动的运动模拟，该模拟已经灭绝的陆生脊椎动物，双足非鸟类兽脚类恐龙腔骨龙. 出乎意料的是，我们的模拟涉及尾部明显的侧屈运动。模拟表明，尾巴不仅是一种静态平衡，还发挥了至关重要的动态作用，侧屈作为一种被动的、基于物理的机制来调节角动量和提高运动经济性，类似于人类的摆臂。我们推断这种机制也存在于许多其他双足非鸟类恐龙中，我们的方法为未来探索恐龙尾巴的功能多样性提供了新途径。