An oxygen-rich atmosphere is essential for complex animals. The early Earth had an anoxic atmosphere, and understanding the rise and maintenance of high O2 levels is critical for investigating what drove our own evolution and for assessing the likely habitability of exoplanets. A growing number of techniques aim to reproduce changes in O2 levels over the Phanerozoic Eon (the past 539 million years). We assess these methods and attempt to draw the reliable techniques together to form a consensus Phanerozoic O2 curve. We conclude that O2 probably made up around 5–10% of the atmosphere during the Cambrian and rose in pulses to ∼15–20% in the Devonian, reaching a further peak of greater than 25% in the Permo-Carboniferous before declining toward the present day. Evolutionary radiations in the Cambrian and Ordovician appear consistent with an oxygen driver, and the Devonian “Age of the Fishes” coincides with oxygen rising above 15% atm. ▪ An oxygen-rich atmosphere is essential for complex animals such as humans. ▪ We review the methods for reconstructing past variation in oxygen levels over the past 539 million years (the Phanerozoic Eon). ▪ We produce a consensus plot of the most likely evolution of atmospheric oxygen levels. ▪ Evolutionary radiations in the Cambrian, Ordovician, and Devonian periods may be linked to rises in oxygen concentration.

中文翻译：

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重新审视显生宙期间大气 O2 的演化


富氧的气氛对于复杂的动物来说是必不可少的。早期地球有一个缺氧的大气层，了解高氧气含量的上升和维持对于研究推动我们自身进化的因素以及评估系外行星可能的宜居性至关重要。越来越多的技术旨在重现显生宙（过去 5.39 亿年）内氧气水平的变化。我们评估这些方法并尝试将可靠的技术整合在一起以形成一致的显生宙 O2 曲线。我们得出的结论是，在寒武纪期间，O2 可能占大气的 5-10% 左右，并在泥盆纪上升至约 15-20%，在二叠纪-石炭纪进一步达到超过 25% 的峰值，然后下降到今天。寒武纪和奥陶纪的进化辐射似乎与氧气驱动因素一致，而泥盆纪的“鱼类时代”则与氧气上升到 15% atm 以上相一致。 ▪ 富氧大气对于人类等复杂动物至关重要。 ▪ 我们回顾了重建过去5.39 亿年（显生宙）氧气水平变化的方法。 ▪ 我们绘制了大气氧含量最可能演变的共识图。 ▪ 寒武纪、奥陶纪和泥盆纪的演化辐射可能与氧浓度的上升有关。