When Life Got Big: The Ediacaran emergence of biological complexity

点击翻译按钮获取中文摘要

The Ediacaran Period, the period immediately before the Cambrian explosion of shelly animal life 541 million years ago, marks a watershed in Earth evolution – the abrupt appearance of multiple groups of large, morphologically complex, life forms after three billion years of Precambrian microbial evolution. Our proposed project will utilize fossil evidence, supplemented by sedimentology and geochemistry of the fossil successions, to document the origin and early development of biological complexity in the Ediacaran oceans. The oldest definite fossils of complex, soft-bodied life forms are 580 million-year-old fronds up to two meters long at Mistaken Point in eastern Newfoundland and equivalent fossils we recently discovered in NW Canada. All known occurrences of the oldest complex life are from deep-water deposits, implying that biological complexity may have arisen in the deep-sea and later spread into shallower-water environments. We will examine these two regions in detail, and will also investigate several other geological sites that are potentially favourable to preserving early large and complex fossils, to test the age and environmental conditions leading to biological complexity and the origin of animals. Some of the questions we will investigate include how Ediacaran life forms achieved large size and complexity, what types of complex organisms characterized early communities of complex life, and the role of oxygen and other factors in the early evolution of complexity. As a related question, we will investigate the evolution of Ediacaran and early Cambrian braininess through an evaluation of the sequential innovations in behavioural complexity shown by burrowing animals during this period. Our studies in NW Canada suggest that Ediacaran burrowers showed minimal responses to environmental stimuli but some Cambrian burrowers showed consistent and strong responses that were probably genetically controlled within the species. We intend to test and refine this hypothesis through studies of Ediacaran and Cambrian trace fosil-rich successions in Newfoundland and southern Africa. This research will provide training for 1 postdoctoral fellow, 4 PhD students, 4 MSc students, and 10 undergraduate assistants/honours thesis students. This origin of animals and other complex life has proven popular among the public and our studies have been featured abundantly in the popular media, including an Emmy Award-winning documentary on early life by Sir David Attenborough. Our key fossil site at Mistaken Point in Newfoundland is also an approved candidate site for consideration as as a possible UNESCO World Heritage Site.