Division of Natural Sciences, Dakota State University, Madison, SD 57042.
Department of Science Education, Chinju National University of Education, Jinju-si, Gyeongnam 52673, South Korea.
Proc Natl Acad Sci U S A. 2024 Oct 29;121(44):e2413810121. doi: 10.1073/pnas.2413810121. Epub 2024 Oct 21.
Body fossils set limits on feasible reconstructions of functional capacity and behavior in theropod dinosaurs, but do not document in-life behaviors. In contrast, trace fossils such as footprints preserve in-life behaviors that can potentially test and enhance existing reconstructions. Here, we demonstrate how theropod trackways can be used as indirect evidence of pre-avian aerial behavior, expanding the approaches available to study vertebrate flight origins. This involved exploring the behavioral implications of a two-toed Cretaceous-aged theropod trackway produced by a small, bird-like microraptorine moving at high speed. Applying first principle running biomechanics, we were able to conclude that the trackway is atypical, indirectly evidencing pre-avian aerial behavior. This trackway documents the evidence of wing-assisted aerodynamic force production during locomotion, supporting a broader distribution of this behavior than currently known. These findings support previously proposed aerial behavior in early bird-like theropods, showing how trackways will help to deepen our understanding of theropod flight origins.
体骨限制了对兽脚亚目恐龙功能能力和行为的可行重建，但不能记录生命中的行为。相比之下，足迹等痕迹化石保留了生命中的行为，这些行为有可能检验和增强现有的重建。在这里，我们展示了兽脚类足迹如何可以作为前鸟类空中行为的间接证据，从而扩展了研究脊椎动物飞行起源的方法。这涉及探索由高速移动的小型鸟类似美颌龙属产生的两趾白垩纪兽脚类足迹的行为意义。应用第一原理跑步生物力学，我们能够得出结论，该足迹是非典型的，间接证明了前鸟类的空中行为。这条足迹记录了在运动过程中翅膀辅助空气动力产生的证据，支持这种行为的分布比目前已知的更为广泛。这些发现支持了早期鸟类状兽脚类动物中提出的空中行为，展示了足迹如何帮助我们加深对兽脚类飞行起源的理解。
