Sun Zhixin, Zhao Fangchen, Zeng Han, Erwin Douglas H, Zhu Maoyan
State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Adv. 2025 May 2;11(18):eadt7572. doi: 10.1126/sciadv.adt7572.
Body size greatly affects how organisms interact with their environments. However, the macroevolutionary patterns of body size across many major metazoan clades and their constraining mechanisms remain elusive. A new high-resolution body size dataset covering 2435 species from 1091 genera of Cambrian and Ordovician trilobites reveals that body size evolution changes episodically, with three marked reductions in size. Such a pattern rules out a persistent Cope's rule dynamic. Rather, we find a strong temporal link between body size changes and major fluctuations in marine redox, supporting the hypothesis that marine oxygen levels exerted a primary control on the tempo and mode of trilobite body size evolution. These further imply a dominant role for marine oxygen in early animal evolution.
体型大小极大地影响着生物体与环境的相互作用方式。然而，许多主要后生动物类群的体型宏观进化模式及其制约机制仍不明确。一个新的高分辨率体型数据集涵盖了寒武纪和奥陶纪三叶虫1091个属的2435个物种，该数据集显示体型进化呈阶段性变化，有三次明显的体型缩小。这种模式排除了持续的柯普法则动态变化。相反，我们发现体型变化与海洋氧化还原的主要波动之间存在着紧密的时间联系，这支持了海洋氧气水平对三叶虫体型进化的节奏和模式施加主要控制的假说。这些进一步暗示了海洋氧气在早期动物进化中起主导作用。
