Spatial and temporal trends in Ediacaran-Cambrian ichnofaunas

埃迪卡拉纪-寒武纪的分界线代表了生命史上的一个主要分界线。埃迪卡拉纪的生物群以软体生物为主，这些生物现在被认为与现代多细胞动物群在很大程度上无关。埃迪卡拉纪生物在全球冰期后繁盛，现在被称为“雪球地球”时期。另一方面，寒武纪见证了几乎所有现代动物群的快速发展，包括骨骼动物群的兴起，这是一个被称为寒武纪大爆发的重大进化创新。大多数关于埃迪卡拉-寒武纪过渡的进化研究都是基于对身体化石的分析。然而，技术记录（由动物留下的足迹、足迹和洞穴组成）提供了一条独立的证据线来校准寒武纪大爆发。最近的许多研究都强调了埃迪卡拉纪生态系统的非现实特征，表明与现代环境不同，这些生态系统由与耐药微生物垫直接相关的底栖生物群落主导。微生物结合稳定沉积物是埃迪卡拉纪生态系统的主要因素。在寒武纪早期，由于垂直生物扰动的开始，基质变得罕见，并在被称为“农艺革命”的事件中被混合地所取代。综合沉积学和技术分析提供了对这些古老生态系统生态学的一瞥，特别是与理解元古宙-寒武纪末期底栖生物群落有关。本项目旨在分析埃迪卡拉-寒武纪区系的时空格局。计划开展的活动包括：(1)对几个埃迪卡拉-寒武纪序列进行野外考察；(2)对痕量化石资料进行修订；(3)建立埃迪卡拉-寒武纪生物动物群数据库；(4)研究压力环境下与微生物基质相关的现代生物成因结构。实地考察将在阿根廷西北部、南非、西班牙、中国、加拿大落基山脉和肯尼亚进行。

The Ediacaran-Cambrian boundary represents a major divide in the history of life. Ediacaran biotas were dominated by soft-bodied organisms that are now considered for the most part to be unrelated with modern multicelular faunas. Ediacaran organisms flourished after a global glaciation that is presently known as the Snowball Earth episode. On the other hand, the Cambrian witnessed the rapid development of almost all modern groups of animals, including the rise of skeletal faunas, a major evolutionary innovation known as the Cambrian explosion. The majority of evolutionary studies on the Ediacaran-Cambrian transition have been based on the analysis of body fossils. However, the ichnologic record (that consisting of tracks, trails and burrows produced by animals) provides an independent line of evidence to calibrate the Cambrian explosion. Many recent studies have stressed the anactualistic character of the Ediacaran ecosystems by showing that, unlike modern environments, these ecosystems were dominated by benthic communities that developed in direct association with resistant microbial mats. Sediment stabilization by microbial binding was a major factor in Ediacaran ecosystems. During the Early Cambrian, matgrounds became rare due to the onset of vertical bioturbation and were replaced by mixgrounds in an event referred to as the "agronomic revolution". Integrated sedimentological and ichnological analysis provides a glimpse into the ecology of these ancient ecosystems and is particularly relevant to understanding the benthic communities of the terminal Proterozoic-Cambrian transition. The aim of this project is to analyze the spatial and temporal patterns of Ediacaran-Cambrian ichnofaunas. Planned activities include: (1) fieldwork in several Ediacaran-Cambrian successions, (2) revision of trace fossil collections, (3) construction of a database of Ediacaran-Cambrian ichnofaunas, and (4) study of modern biogenic structures associated with microbial matgrounds in stressed environments. Fieldwork will be done in northwest Argentina, South Africa, Spain, China, the Canadian Rockies and Kenya.