How disastrous was Oceanic Anoxic Event 2? A shelf versus deep-sea comparison from the echinoderm perspective

深海是迄今为止地球上分布最广的环境，然而我们对深海生物群的组成、生物多样性和起源的认识仍然非常贫乏。特别模糊的是地质历史和现代大型底栖动物的进化动力学。深海生物群要么是相对较新的，由与深海环境的大规模破坏有关的多次翻转造成的，要么是古老的，可能对这种变化有弹性。这场争论没有解决的原因是深海底栖动物的地质历史缺乏直接证据，因为深海沉积物的露头没有保存下来的化石遗骸。最近，我们发现了一种意想不到的可能性，可以研究深海底栖动物的进化，为评估深海生态系统的进化起源提供关键的直接证据。在一项初步研究中，我们在海洋钻探计划回收的中白垩纪沉积物中发现了大量可识别的棘皮动物化石骨骼残骸。在这个项目中，我们将以这一发现为基础，使用DSDP/ODP材料系统地评估下白垩纪深海棘皮动物群落的组成和多样性，以测试它们是否与现代同类有显著差异，以及深海动物群的最后一次重大重组发生在什么时候。该项目为ODP/DSDP材料提供了一个新的视角，可以基于大型底栖动物群体的微化石记录开创一个全新的应用范围。

The deep sea is by far the most widespread environment on the planet, yet our knowledge on thecomposition, biodiversity and the origin of the deep-sea biota remains remarkably poor. Particularlyobscure is the geological history and the evolutionary dynamics of the present-day macrobenthos. Thedeep-sea biota is either relatively recent, resulting from multiple turnovers linked to large disruptions ofthe deep sea environment, or it is ancient and presumably resilient to such changes. The reason whythis debate is unsettled is the lack of direct evidence on the geological history of deep-seamacrobenthos due to the absence of outcrops of deep-sea sediments with preserved fossil remains.Recently, we have identified an unexpected possibility to investigate the evolution of deep-seamacrobenthos and provide key direct evidence to assess the evolutionary origin of the deep-seaecosystems. In a pilot study, we have discovered significant quantities of identifiable skeletal remainsof fossil echinoderms in mid-Cretaceous sediments recovered by the Ocean Drilling Program. In thisproject we will build on this discovery and use DSDP/ODP material to systematically assess thecomposition and diversity of Lower Cretaceous deep-sea echinoderm communities in order to testwhether they significantly differ from modern equivalents and when the last major reorganisation of thedeep-sea fauna took place. This project gives a new perspective to ODP/DSDP material that could setoff an entirely new range of applications based on the microfossil record of macrobenthic groups.