Determining the nature and drivers of Earth's first metazoan radiation and subsequent extinction: The Cambrian 'Explosion' and Sinsk Event

寒武纪辐射，开始CA。5.4亿年前（Ma），标志着化石记录中丰富多样的动物（后生动物）的出现。这种辐射可能是由振荡的海洋氧化和生产力事件驱动的，但被第一次大规模灭绝，即“辛斯克事件”所终止。公元513年。辛斯克事件被认为是一个广泛的海洋缺氧的高温间隔，重新设定了所有后续后生动物生命的轨迹。然而，尽管它对地球的可居住性和复杂生命的进化过程具有重要意义，但人们对这一事件的驱动因素或哪些环境因素控制了灭绝选择性知之甚少。我们假设，这是低海洋硫酸盐水平，促进振荡氧化，从而创造脉冲后生动物辐射，但矛盾的是，这也使早期寒武纪浅海高度容易缺氧，以应对全球变暖，从而终止这些辐射与深刻的灭绝。我们提出了一个雄心勃勃的综合古生物学，地球化学和建模方法，以解开辐射的控制过程，以及神秘的，但非常重要的，辛斯克事件的后果。通过比较寒武纪辐射的驱动因素与其消亡的驱动因素，我们将解决一个基本的激励问题：低硫酸盐海是否既促进了辐射，又推动了地球历史的发展？

The Cambrian Radiation, starting ca. 540 million years ago (Ma), marks the appearance of abundant and diverse animals (metazoans) in the fossil record. This radiation may have been driven by oscillating ocean oxygenation and productivity events, but was terminated by the first mass extinction, the 'Sinsk Event', ca. 513 Ma. The Sinsk Event is considered to have been a hyperthermal interval of widespread ocean anoxia that reset the trajectory for all subsequent metazoan life. However, despite its significance for the course of Earth's habitability and the evolution of complex life, little is known about the drivers of this event, or which environmental factors controlled extinction selectivity. We hypothesise that it was low oceanic sulphate levels that promoted oscillating oxygenation, so creating pulsed metazoan radiations, but paradoxically this also made the early Cambrian shallow ocean highly susceptible to anoxia in response to global warming, thereby terminating these radiations with a profound extinction. We propose an ambitious integrated palaeobiological, geochemical and modelling approach to unravel the controlling processes of radiations, and the consequences of the enigmatic, but highly significant, Sinsk Event. By comparing the drivers of the Cambrian Radiation with those of its demise, we will address a fundamental motivating question: Did low sulphate seas both promote radiations and drive extinctions through Earth History?