Troyer Emily M, Rivero-Vega Rafael A, Cui Xindong, Zhu Min, Qiao Tuo, Saad Hadeel H, Figueroa Rodrigo T, Andrews James V, Clement Alice M, Lebedev Oleg A, Higgins Robert, Igielman Benjamin, Pierce Stephanie E, Giles Sam, Friedman Matt
Museum of Paleontology and Department of Earth and Environmental Sciences, University of Michigan, 1105 North University Avenue, Ann Arbor, MI 48109, USA.
Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China.
Curr Biol. 2025 Aug 27. doi: 10.1016/j.cub.2025.08.008.
The evolution of jaws is hypothesized to have fueled radiations among vertebrates, contributing to their overwhelming success in the present day. Past work shows rapid early expansion of diversity in jaw structure in many lineages; however, the evolutionary dynamics underlying this pattern are unclear and hindered by the lack of a robust comparative framework. Here, using a macroevolutionary approach, we explore the diversification of lower jaws in early bony fishes, a major contributor to this initial radiation. Using newly generated three-dimensional mandibular shape data from 86 species, we find evidence of adaptive radiation in jaws during the earliest interval of bony fish evolutionary history (423-359 Ma). These patterns are principally driven by early lungfishes and coelacanths, which display high rates of jaw diversification, rapid shifts into novel functional regions of trait space, and substantial innovation in jaw morphology and feeding ecology, standing in contrast to their "living fossil" descendants of today. Conversely, ray-finned fishes and tetrapodomorphs, morphologically diverse groups in the present day, show little indication of their future success, possessing slow rates of jaw evolution and low functional diversity. This profound inversion of patterns in modern taxa highlights the significance of paleontological data in understanding drivers of evolutionary diversification and the limitations of approaches using only living species. Overall, our findings provide insight into the evolutionary dynamics associated with the evolution of jaws and provide context for the role of jaws in vertebrate success.
据推测，颌骨的进化推动了脊椎动物的辐射演化，促成了它们如今的巨大成功。过去的研究表明，许多谱系的颌骨结构多样性在早期迅速扩张；然而，这种模式背后的进化动态尚不清楚，且因缺乏一个强大的比较框架而受到阻碍。在这里，我们采用宏观进化方法，探索早期硬骨鱼类下颌的多样化，硬骨鱼类是这一初始辐射演化的主要贡献者。利用新生成的86个物种的三维下颌形状数据，我们发现了在硬骨鱼类进化历史的最早阶段（4.23亿至3.59亿年前）颌骨适应性辐射的证据。这些模式主要由早期肺鱼和腔棘鱼驱动，它们表现出较高的颌骨多样化速率、迅速转向性状空间的新功能区域，以及颌骨形态和摄食生态的重大创新，这与它们如今的“活化石”后代形成鲜明对比。相反，如今形态多样的辐鳍鱼类和四足形类动物，几乎没有显示出它们未来成功的迹象，其颌骨进化速率缓慢且功能多样性较低。现代类群中这种模式的深刻反转凸显了古生物学数据在理解进化多样化驱动因素方面的重要性，以及仅使用现存物种的方法的局限性。总体而言，我们的研究结果为与颌骨进化相关的进化动态提供了见解，并为颌骨在脊椎动物成功中的作用提供了背景信息。
