Spatial and temporal trends in Ediacaran-Cambrian ichnofaunas

埃迪卡拉纪和寒武纪的界线代表着生命历史上的一个重大分水岭。埃迪卡拉纪生物群主要是软体生物，现在认为它们在很大程度上与现代多细胞动物群无关。埃迪卡拉生物在全球冰川之后蓬勃发展，现在被称为雪球地球事件。另一方面，寒武纪见证了几乎所有现代动物群体的快速发展，包括骨骼动物群的兴起，这是一种被称为寒武纪爆发的重大进化创新。大多数关于埃迪卡拉纪-寒武纪过渡的进化研究都是基于对遗体化石的分析。然而，生物记录(包括动物留下的足迹、踪迹和洞穴)提供了一条独立的证据线来校准寒武纪的爆炸。最近的许多研究强调了埃迪卡拉生态系统的非精算性特征，表明与现代环境不同，这些生态系统主要由底栖生物群落主导，这些群落与耐药微生物垫直接相关。微生物结合稳定沉积物是埃迪卡拉生态系统中的一个主要因素。在早寒武世，由于垂直生物扰动的开始，草地变得稀少，取而代之的是混合草地，这一事件被称为“农学革命”。综合的沉积学和生物分析提供了对这些古老生态系统生态的一瞥，对于了解元古界末期-寒武纪过渡时期的底栖生物群落特别相关。该项目的目的是分析埃迪卡拉纪-寒武纪遗迹动物群的空间和时间格局。计划开展的活动包括：(1)在几个埃迪卡拉纪-寒武纪序列中进行实地考察；(2)修订遗迹化石收藏；(3)建立埃迪卡拉纪-寒武纪遗迹动物群数据库；(4)研究与压力环境中的微生物地有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.