The colonisation of freshwater and marine ecosystems by land vertebrates has repeatedly occurred in amphibians, reptiles, birds and mammals over the course of 300 million years. Functional interpretations of the fossil record are crucial to understanding the forces shaping these evolutionary transitions. Secondarily aquatic tetrapods have acquired a suite of anatomical, physiological and behavioural adaptations to locomotion in water. However, much of this information is lost for extinct clades, with fossil evidence often restricted to osteological data and a few extraordinary specimens with soft tissue preservation. Traditionally, functional morphology in fossil secondarily aquatic tetrapods was investigated through comparative anatomy and correlation with living functional analogues. However, in the last two decades, biomechanics in palaeobiology has experienced a remarkable methodological shift. Anatomy-based approaches are increasingly rigorous, informed by quantitative techniques for analysing shape. Moreover, the incorporation of physics-based methods has enabled objective tests of functional hypotheses, revealing the importance of hydrodynamic forces as drivers of evolutionary innovation and adaptation. Here, we present an overview of the latest research on the locomotion of extinct secondarily aquatic tetrapods, with a focus on amniotes, highlighting the state-of-the-art experimental approaches used in this field. We discuss the suitability of these techniques for exploring different aspects of locomotory adaptation, analysing their advantages and limitations and laying out recommendations for their application, with the aim to inform future experimental strategies. Furthermore, we outline some unexplored research avenues that have been successfully deployed in other areas of palaeobiomechanical research, such as the use of dynamic models in feeding mechanics and terrestrial locomotion, thus providing a new methodological synthesis for the field of locomotory biomechanics in extinct secondarily aquatic vertebrates. Advances in imaging technology and three-dimensional modelling software, new developments in robotics, and increased availability and awareness of numerical methods like computational fluid dynamics make this an exciting time for analysing form and function in ancient vertebrates.

中文翻译：

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已灭绝的次生水生四足动物的运动

在 3 亿年的时间里，陆地脊椎动物对淡水和海洋生态系统的殖民化在两栖动物、爬行动物、鸟类和哺乳动物身上反复发生。化石记录的功能解释对于理解塑造这些进化转变的力量至关重要。其次，水生四足动物已经获得了一套在水中运动的解剖学、生理学和行为适应能力。然而，对于已灭绝的进化枝，大部分信息都丢失了，化石证据通常仅限于骨学数据和一些具有软组织保存的非凡标本。传统上，化石次生水生四足动物的功能形态是通过比较解剖学和与活体功能类似物的相关性来研究的。然而，在过去的二十年里，古生物学中的生物力学经历了显着的方法论转变。通过分析形状的定量技术，基于解剖学的方法越来越严格。此外，基于物理学的方法的结合使功能假设的客观测试成为可能，揭示了水动力作为进化创新和适应驱动力的重要性。在这里，我们概述了关于已灭绝的次生水生四足动物运动的最新研究，重点是羊膜动物，重点介绍了该领域使用的最先进的实验方法。我们讨论了这些技术在探索运动适应的不同方面的适用性，分析它们的优点和局限性，并为它们的应用提出建议，旨在为未来的实验策略提供信息。此外，我们概述了一些尚未探索的研究途径，这些途径已成功应用于古生物力学研究的其他领域，例如在摄食力学和陆地运动中使用动态模型，从而为灭绝的次生水生生物力学领域提供新的方法论综合。脊椎动物。成像技术和 3D 建模软件的进步、机器人技术的新发展，以及计算流体动力学等数值方法的可用性和意识的提高，使得现在成为分析古代脊椎动物形态和功能的激动人心的时刻。例如在摄食力学和陆地运动中使用动态模型，从而为已灭绝的次生水生脊椎动物的运动生物力学领域提供了一种新的方法论综合。成像技术和 3D 建模软件的进步、机器人技术的新发展，以及计算流体动力学等数值方法的可用性和意识的提高，使得现在成为分析古代脊椎动物形态和功能的激动人心的时刻。例如在摄食力学和陆地运动中使用动态模型，从而为已灭绝的次生水生脊椎动物的运动生物力学领域提供了一种新的方法论综合。成像技术和 3D 建模软件的进步、机器人技术的新发展，以及计算流体动力学等数值方法的可用性和意识的提高，使得现在成为分析古代脊椎动物形态和功能的激动人心的时刻。