When Life Got Big: The Ediacaran emergence of biological complexity

埃迪卡拉纪，即5.41亿年前寒武纪贝壳类动物大爆发之前的一段时期，标志着地球进化的一个分水岭——经过30亿年的前寒武纪微生物进化，突然出现了多群大型、形态复杂的生命形式。我们提出的项目将利用化石证据，辅以化石演替的沉积学和地球化学，来记录埃迪卡拉纪海洋生物复杂性的起源和早期发展。最古老的确定的复杂软体生命形式化石是在纽芬兰东部的错误点发现的5.8亿年前长达两米的叶子，以及我们最近在加拿大西北部发现的类似化石。所有已知的最古老的复杂生命都来自深海沉积物，这意味着生物复杂性可能在深海中出现，后来扩散到浅水环境中。我们将详细研究这两个地区，并将调查其他几个可能有利于保存早期大型复杂化石的地质遗址，以测试导致生物复杂性和动物起源的年龄和环境条件。我们将研究的一些问题包括埃迪卡拉时代的生命形式是如何达到巨大的规模和复杂性的，什么样的复杂生物是复杂生命早期群落的特征，以及氧气和其他因素在复杂性早期进化中的作用。作为一个相关的问题，我们将通过评估穴居动物在这一时期表现出的行为复杂性的连续创新来研究埃迪卡拉纪和寒武纪早期大脑的进化。我们在加拿大西北部的研究表明，埃迪卡拉的穴居动物对环境刺激的反应最小，但一些寒武纪的穴居动物表现出一致和强烈的反应，这可能是由物种内部的遗传控制的。我们打算通过对纽芬兰和非洲南部埃迪卡拉纪和寒武纪富含化石的序列的研究来检验和完善这一假设。本研究将培养1名博士后、4名博士生、4名硕士生、10名本科生助理/荣誉论文学生。事实证明，动物和其他复杂生命的起源在公众中很受欢迎，我们的研究在大众媒体上得到了大量的报道，包括大卫·阿滕伯勒爵士拍摄的一部关于早期生活的艾美奖获奖纪录片。我们在纽芬兰的错误点的主要化石遗址也被批准为联合国教科文组织世界遗产的候选地点。

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.