The trace-fossil record of the Cambrian explosion

寒武纪大爆发的痕迹化石记录

• 批准号: RGPIN-2015-05021
• 负责人: Mangano, Maria
• 金额: $ 2.99万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633831
• 关键词: trace; fossil; record; Cambrian; explosion

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-bodiedorganisms, 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 thissecond 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 theCambrian 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.

寒武纪大爆发是生命史上最具戏剧性的事件之一。在埃迪卡拉纪（Ediacaran）之后，软体生物在生物群中占主导地位，化石记录迅速变化，下寒武纪岩石中出现了几乎所有基本动物体型的化石代表。关于动物的早期进化有两种对立的观点，一种观点认为化石记录只是表面上的价值，支持现代动物门快速起源的观点（寒武纪大爆发）。另一种观点强调化石记录的不完美性，强调后生动物进化历史中前寒武纪的深层根源。根据这第二种观点，化石在中生代开始时的突然出现只是一种人为现象，这是由于与获得矿化骨骼有关的身体化石的可吸收性增加而造成的。遗迹学包括对生物和基质之间相互作用产生的生物结构（称为遗迹化石）的研究。由于遗迹化石通常是由软体动物产生的，它们不像身体化石那样受到同样的限制。因此，遗迹化石可以提供一个独立的证据线来校准寒武纪大爆发。本项目的目标是：（1）记录与寒武纪大爆发及其Fortunian前奏有关的遗迹动物群;（2）在生物圈历史的关键时期，探索遗迹化石的潜力，以提高我们对寒武纪生态系统建设的认识;以及（3）探索遗迹学信息如何提供对这个突破的时间和环境约束的见解，揭示了进化创新中潜在的历时性。