The rise of the ruling reptiles and ecosystem recovery from the Permian-Triassic mass extinction

One of the key faunal transitions in Earth history occurred after the Permo-Triassic mass extinction (ca. 252.2 Ma), when the previously obscure archosauromorphs (which include crocodylians, dinosaurs, and birds) become the dominant terrestrial vertebrates. Here, we place all known middle Permian–early Late Triassic archosauromorph species into an explicit phylogenetic context, and quantify biodiversity change through this interval. Our results indicate the following sequence of diversification: a morphologically conservative and globally distributed post-extinction ‘disaster fauna’; a major but cryptic and poorly sampled phylogenetic diversification with significantly elevated evolutionary rates; and a marked increase in species counts, abundance, and disparity contemporaneous with global ecosystem stabilisation some 5 million years after the extinction. This multiphase event transformed global ecosystems, with far-reaching consequences for Mesozoic and modern faunas.

地球历史上的关键动物群转变事件之一，发生于二叠纪-三叠纪大灭绝（Permo-Triassic mass extinction，约2.522亿年前）之后——彼时此前鲜为人知的主龙形类（archosauromorphs，包含鳄类、恐龙与鸟类）一跃成为陆地脊椎动物的优势类群。本研究将所有已知的中二叠世至早三叠世晚期的主龙形类物种纳入明确的系统发育分析框架，并量化了该时段内的生物多样性变化历程。我们的研究结果揭示了如下多阶段辐射演化序列：灭绝事件后首先出现形态保守、全球广布的“灾难动物群”；随后发生一次规模宏大却隐秘、采样不足且演化速率显著提升的系统发育辐射；而在灭绝事件发生约500万年后，伴随全球生态系统趋于稳定，物种种数、个体丰度与形态分异度（disparity）均出现显著增长。这一多阶段演化事件重塑了全球陆地生态系统，对中生代乃至现代的动物群均产生了深远影响。