DARWIN'S l LOST f The hidden history of animal life MARTI N BRASI ER . ‘The case at present mu- m inexplicable . Darwin wrote in The Origin ofSpecies. The rocks beyond the trilobite-laden Cambrian seemed to be barren. Where were the fossil ancestors to all those amazing early animals? This book is about the quest to solve Darwin’s Dilemma. Since Darwin’s time, palaeontologists have been seeking the hidden history of animals. And sure enough, they have found fossils, all over the world, going back far into the past; fossils that would have thrilled Darwin—large, enigmatic marine forms, and a veritable feast of tiny single cells. But the relatively sudden (geologically speaking) dawn of the modern world of animals—the ‘Cambrian explosion’—has remained a puzzle. Was it really an ‘explosion’ of new forms? Or was it simply an explosion of fossils, once animals acquired hard parts which could be well preserved? In this highly personal and engaging book, Martin Brasier, one of the key players in the study ofPrecambrian life, describes the nature and challenges of the quest, which has taken scientists to the remotest locations. He argues that the Cambrian explosion was real—a genuine and profound change affecting the whole Earth system. And the cause may have been intrinsic to life itself. Small changes can cascade into massive ones. It might only have taken the appearance of one or a handful ofpredators to change the world. The Cambrian explosion was a watershed: once life acquired teeth, the Earth was never the same again. Received on: D A R W I N ’SI. O S T W O R I.. D ' DARWIN'S LOST WORLD The Hidden. History of: Animal Life MARTIN BRASIER OXPORD UNIVERSITY PRESS OXFORD UNIVERSITY PRESS Great Clarendon Street, Oxford 0x2 6dp Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offices in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States by Oxford University Press Inc., New York < Martin Brasier 2009 The moral rights of the author have been asserted Database right Oxford University Press (maker) First published 2009 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, ** without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose the same condition on any acquirer British Library Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data Data available Typeset by SPI Publisher Services, Pondicherry, India Printed in the UK on acid-free paper by CPI William Clowes Beccles NR34 7TL ISBN 978-0-19-954897-2 1 3 5 7 9 10 8 6 4 2 CONTENTS Preface vi List ofFigures xi List of Colour Plates xiii m i. In Search of Lost Worlds I 2. The Devil’s Toenail 35 3. A Fossilized Jelly Baby 63 4. The First Terror with Teeth 93 5. A Worm that Changed the World 119 6. A Mistaken Point 139 7. Reign of the Snow Queen 178 8. Through a Lens, Darkly 204 9. Torridon 234 Notes 261 References 285 Index 295 PREFACE ome 150 years ago, in 1859, Charles Darwin was greatly S puzzled by a seeming absence of animal fossils in rocks older than the Cambrian period. He drew attention to a veritable Lost World that was later found to have spanned more than eighty per cent of Earth history. This book tells the story of his lost world, and of the quest to rescue its hidden history from the fossil record. Intriguingly, such a quest did not really begin until 1958, some hundred years after Darwin. Why did an understanding take so long? Arguably it was because it was, and still remains, a very big and very difficult problem. Its study now involves the whole of the natural sciences. Progress has been a matter of slow attrition. For most of this time, for example, there has been no concept of the vast duration of Precambrian time, nor any evidence for a distinct biota. >r. This book follows the story of my own research history, begin- ning with a cruise as Ship’s Naturalist on HMS Fawn studying Caribbean marine ecosystems. Like my own researches, it then pushes ever further backwards through time, from an inquisition into the nature of the Cambrian explosion and the enigmatic Ediacara biota some 600 to 500 million years ago, towards the vi PREFACE emergence of the earliest complex cells some 1000 million years back. Each step backwards in time has drawn me towards ever, more remote and little known parts of the planetary landscape, and towards equally puzzling parts of the human mental land- scape. I have therefore sought, in each chapter, to put some of the major questions into context by descriptions of premier field locations from around the world, enlivened by descriptions of their fossils, their fossil hunters, and their puzzles. My hope is that the book will show just how rich and diverse have been our ways of thinking about the earliest life forms, written in words that can hopefully be read with ease and enjoy- ment. Good science is, after all, not just about facts. It should be a form of play. If a thing is not playful, it is probably not good science. Each generation has therefore come up with its own favourite solution to the question— whence cometh life?—only to watch it fall as the next generation of science and scientists has arrived on the scene and found even better solutions. Deep down, my hope is that the book will show how my subject works as a science, how the questions are being shaped, and how the early loss'll record of animal life may yet be decoded, bringing the world of ancient and modern life right to the doorstep of all those who are curious and wish to learn about the rich history of life beneath their feet. Here, then, is your passport to becoming a Time Traveller, and to making your own exciting discoveries about the world in which we really live. The fossil record is your best guide for decoding pattern and process and the meaning of life. And the starting point for the reading of patterns is your own natural curiosity spiced with a modicum of doubt. Happily, science is a uniquely valuable system for the measurement of doubt. vii PREFACE As my colleague Andy Knoll at Harvard has so rightly put it: ‘science is a richly social endeavour.’ Nothing in science would be possible without the support of a network of friends and colleagues. I here express my deep gratitude to the following hne teachers and mentors for encouraging my involvement in a life- time’s research into early life, roughly from the 1960s onward: John Dewey, Tony Barber, Bill Smith, Martin Glaessner, Perce Allen, Roland Goldring, Stewart McKerrow, Fran^oise and Max Debrenne, Michael House, John Cowie, Peter Cook, John Shergold, and Stephen Moorbath. I thank my colleagues Jonathan Antcliffe and Latha Menon for acting as major catalysts for this popular (or possibly unpopular) account and for giving me greatly appre- ciated advice upon the written word. The following geologists from around the world are here lauded for their invaluable assist- ance during field work, often in remote and hostile places, followed up by laboratory work, over four decades: Owen Green for his kind support in field and lab, and for running the Palaeobiology Labs at Oxford; my extended family of students and proteges including Duncan Mcllroy, Graham Shields, Louise Purton, Gretta McCarron, David Wacey, Jonathan Leather, Zhou Chuanming, Nicola McLoughlin, Jon Antcliffe, Maia Schweizer, Richard Callow, Alexander Liu, Leila Battison, and Latha Menon for so many years of lively and fruitful discussion in field, lab and pub; and the following for their much valued support and friend- ship in the field: Alexei Rozanov, Andrei Zhuravlev, and Vsevelod Khomentovsky in Siberia and Mongolia from 1990 to 1993; Xiang Liwen, Xing Yusheng, Yue Zhao, Jiang Zhiwen, Luo Huilin, He Tinggui, and Sun Weiguo in China from 1986 to 2007; Lena Zhegallo, D. Dorjnamjaa, Bat-Ireedui, Rachael Wood, Simon Conway Morris, and Stefan Bengtson in Mongolia from 1991 to 1993; Dhiraj Banerjee in India in 1990 and Pratap Singh for the viii PREFACE donation of key Tal material; Joachim Amthor, Salim El Maskery, Philip Allen, and John Grotzinger in Oman; Petroleum Develop- ment Oman and the staff of Shell International for their generous support of Oman field work from 1994 to 2000; Philip Allen and John Grotzinger for showing me how to be a Precambrian sedimentologist; Bahaeddin Hamdi for generous provision of Iran samples and field notes; Eladio Linan, Antonio Perejon, and Miguel-Angel de San Jose in Spain from 1978; Trevor Ford, Helen Boynton, Mike Harrison, Lady Martin, Mike Howe, John Carney, and numerous other kind people for their support of fieldwork in England and Wales at various times since 1965; Michael and Alison Lewis for making their Welsh farmhouse a home to Cambrian fieldwork over many decades; Mike Anderson, Ed Landing, Guy Narbonne, Caas van Staal, Bob Dalrymple, and Duncan Mcllroy for major help with fieldwork in Newfoundland and Nova Scotia since 1987; John Hanchar and his team at Memorial University in Newoundland for their encouragement and support; John Lindsay of NASA and Cris Stoakes in Perth for their enormous enthusiasm and encouragement and greatly valued companionship and hospitality during fieldwork across Australia from 1998 to 2006; Jim Gehling, Dave McKirdy, Richard Jenkins, and Pierre Kruse for their guidance and hospitality in the Adelaide and Darwin regions of Australia in 1998.