The trace-fossil record of the Cambrian explosion

寒武纪大爆炸代表着生命历史上最戏剧性的事件之一。在经历了一段被称为埃迪卡拉纪(Ediacaran)的时期后，生物群由软体生物主导，化石记录迅速变化，这一点从寒武纪下部岩石中几乎所有基本动物身体平面的化石代表的出现中可见一斑。关于动物的早期进化有两种相反的观点。一种观点认为化石记录只是表面价值，倾向于现代门的快速起源(寒武纪大爆发)的情景。另一种观点强调化石记录的不完美性质，强调后生动物进化史中有深厚的前寒武纪根源的概念。根据这一*第二种观点，化石在显生界开始附近突然出现，只是与矿化骨骼获取相关的遗体化石保存性增加而产生的一种器物。生物信息学包括研究生物有机体和底物之间相互作用产生的生物起源结构(称为痕迹化石)。由于遗迹化石通常由软体动物产生，因此它们不会受到与身体化石相同的保护约束。因此，遗迹化石可能会提供一条独立的证据线来校准前寒武纪的爆炸。该项目的主要目标是：(1)记录与寒武纪爆发及其福图尼纪前奏有关的生物动物群；(2)探索遗迹化石的潜力，以提高我们对生物圈历史上关键时刻寒武纪生态系统建设的理解；以及(3)探索化石信息如何提供对寒武纪爆发的时间和环境限制的见解，揭示进化和创新中潜在的历时性。

The Cambrian explosion represents one of the most dramatic episodes in the history of life. Following a period known as Ediacaran, when biotas were dominated by soft-bodied*organisms, the fossil record changed rapidly as revealed by the appearance of fossilized representatives of almost all the basic animal body plans in lower Cambrian rocks. There are two opposed views on the early evolution of animals. One view considers the fossil record at face value, favoring a scenario of rapid origination of modern phyla (the Cambrian explosion). The other view stresses the imperfect nature of the fossil record, stressing the notion of deep Precambrian roots in metazoan evolutionary history. According to this*second perspective, the sudden appearance of fossils near the beginning of the Phanerozoic is just an artifact resulting from an increase in preservability of body fossils related to the acquisition of mineralized skeletons. Ichnology comprises the study of biogenic structures (known as trace fossils) that result from the interactions between organisms and the substrate. Because trace fossils are commonly produced by soft-bodied animals, they are not subjected to the same preservational constrains than body fossils. Accordingly, trace fossils may offer an independent line of evidence to calibrate the Cambrian explosion. The objectives of this project are: (1) to document ichnofaunas associated with the*Cambrian explosion and its Fortunian prelude, (2) to explore the potential of trace fossils to improve our understanding of Cambrian ecosystem construction at a critical time in the history of the biosphere; and (3) to explore how ichnologic information provides insights into the timing and environmental constrains of this breaktrough, revealing potential diachronism in evolutionary innovations.******