Cowen’s History of Life Cowen’s History of Life Edited by Michael J. Benton Written by Michael J. Benton, John Cunningham, Tom Davies, Philip C. J. Donoghue, Andy Fraass, Christine Janis, Davide Pisani, Emily Rayfield, Daniela Schmidt, Jakob Vinther, and Tom Williams Palaeobiology Research Group University of Bristol UK Sixth Edition This sixth edition first published 2020 © 2020 John Wiley & Sons Ltd Edition History 5e: 9780470671726 (Wiley 2013) 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, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions. The right of Michael J. Benton to be identified as the author of the editorial material in this work has been asserted in accordance with law. 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Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. Library of Congress Cataloging‐in‐Publication Data Names: Benton, M. J. (Michael J.), author. | Cowen, Richard, 1940– History of life. Title: Cowen’s history of life / edited by Michael J. Benton ; written by Michael J. Benton, John Cunningham, Tom Davies, Philip C. J. Donoghue, Andy Fraass, Christine Janis, Davide Pisani, Emily Rayfield, Daniela Schmidt, Jakob Vinther, and Tom Williams, Palaeobiology Research Group, University of Bristol. Other titles: History of life Description: Sixth edition. | Hoboken, NJ : Wiley-Blackwell, [2019] | Includes index. | Identifiers: LCCN 2019015116 (print) | LCCN 2019017612 (ebook) | ISBN 9781119482208 (Adobe PDF) | ISBN 9781119482222 (ePub) | ISBN 9781119482215 (paperback) Subjects: LCSH: Paleontology. Classification: LCC QE711.2 (ebook) | LCC QE711.2 .C68 2019 (print) | DDC560–dc23 LC record available at https://lccn.loc.gov/2019015116 Cover Design: Wiley Cover Image: © Sergey Krasovskiy/Getty Images Set in 10/12pt Warnock by SPi Global, Pondicherry, India 10 9 8 7 6 5 4 3 2 1 v Contents Preface vii About the Companion Website xi 1 The Origin of Life on Earth 1 2 The Earliest Life on Earth 17 3 The Origin of Eukaryotes 33 4 The Evolution of Metazoans 45 5 The Cambrian Explosion 59 6 Changing Life in a Changing World 71 7 The Early Vertebrates 93 8 Leaving the Water 109 9 Early Tetrapods and Amniote Origins 123 10 Early Amniotes and Thermoregulation 137 11 The Mesozoic Marine Revolution 151 12 The Triassic Takeover 169 13 Dinosaurs 181 14 Birds and the Evolution of Flight 203 15 The Cretaceous Terrestrial Revolution 219 16 The End of the Dinosaurs 233 17 Changing Oceans and Climates 245 18 The Origin of Mammals 263 19 Cenozoic Mammals 277 vi Contents 20 Geography and Evolution 297 21 Primates 313 22 Evolving Toward Humans 325 23 Life in the Ice Age 343 Glossary 361 Index 369 vii Preface Authorship extensively about scientific topics. In his day, people found fossil shells in the limestone mountains of central This book is based on the classic work through five Italy, and they wondered how they got there. Had the editions by Richard Cowen, and many of his words Roman soldiers dumped the shells after eating their remain in this new edition. Among the team of revisers, lunch? Leonardo realized, correctly, that these limestones Mike Benton led the revision, contributing more or less had been deposited in the sea, and that the mountains to all chapters, supported by Tom Williams (Chapters had subsequently been uplifted. He realized the Earth 1 – 3), John Cunningham (Chapters 4 and 5), Davide was ancient, and the animals that had inhabited the shells Pisani (Chapters 3 – 5), Phil Donoghue (Chapters 4, 5, 7 truly had once lived on the seabed, and it took millions of and 8), Daniela Schmidt and Andy Fraass (Chapter 17), years for them to reach their present location, many Christine Janis and Emily Rayfield (Chapters 18 – 21 and miles from the sea. 23), and Tom Davies (Chapter 22). Great debates in science in later times focused around rocks and fossils – could extinct species of often unfa- miliar appearance even exist? How ancient is the Earth? For Everyone Has life evolved or simply been created in an instant? Are humans merely naked apes or are they in some way spe- Richard Cowen’s History of Life has run through five edi- cial? How do environmental changes such as rising sea tions since it first appeared in 1990. He based the book levels, rising temperatures, and ocean acidification affect on his long experience as an instructor at the University life? The paleontologist has (some of) the answers. of California, Davis, teaching a course called “History of Since 1990, when History of Life first appeared, our Life” for 40 years. As he said in his Preface to the fifth knowledge of paleontology has changed enormously – edition, the book “is meant not just for students, but for think of the thousands of extraordinary new discoveries everyone interested in the history of life on our planet. from China: the early animals from Chengjiang, the Fortunately, paleontology (= paleobiology) is accessible Silurian fishes from Yunnan, the feathered dinosaurs and to the average person without deep scientific training. birds from northern China, and many more. Every week, My aim is ambitious: I try to take you to the edges of our exciting new finds are made, adding records of the very knowledge in paleontology, showing you how life has oldest traces of life on Earth, early microbes, plants, and evolved on Earth, and how we have reconstructed animals that tell us about the origins of modern biodiver- the history of that evolution from the record of rocks sity. A new dinosaur species is named every two weeks. and fossils.” In a way, more important than the new fossil finds are The story of the history of life is of profound interest to the changes in methods. Richard Cowen has lived through many because it addresses core questions in philosophy several revolutions in paleobiology. First came cladistics, and knowledge, especially about origins, crises, and envi- a set of methods to draw up evolutionary trees according ronmental change. Since the times of the earliest thinkers to rules, so that the trees are testable hypotheses rather in China, India, and Greece, people have asked questions than merely guesses. Then came phylogenomics, a about where humans came from and how we relate to the wholly new set of methods to draw up evolutionary trees plants and animals we see around us. During the develop- using gene sequences from DNA and RNA, to provide an ment of modern science in Europe, great philosophers independent test of the fossil‐based trees. Then came have debated what fossils are and what the rocks show us. massive improvements in stratigraphy, with fine tuning As an example, Leonardo da Vinci (1452–1519), as of methods such as radiometric dating and astrochronol- well as being one of the greatest artists of all time, wrote ogy, so that events can now be dated with much greater viii Preface precision than was imagined in the 1980s. These three The book is aimed at students and we hope some will fields of science provide the essential backdrop for pale- be inspired to find out more, and perhaps sign up for ontology – a well‐dated evolutionary tree. further courses on paleontology, paleobiology, historical Then there were revolutions in the way paleontologists geology, macroevolution, and related topics. It’s a great life study macroevolution. First came the explosion of inter- as a paleontologist, even though jobs are thinly spread. est in mass extinctions, whether caused by asteroid In this new edition, we have kept the basic structure impact or massive volcanic eruption – this is a field that and have substantially rewritten chapters on the origins attracts huge interest from multidisciplinary teams of of eukaryotes, the Cambrian explosion, the terrestrializa- paleontologists, geologists, geochemists, astronomers, tion of plants and animals, the Triassic recovery of life, and ecological modelers. New methods of phylogenetic the origin of birds, the end‐Cretaceous mass extinction, comparative methods (PCM) allowed paleobiologists to and human evolution. We have added three new chap- explore diversifications, times when new groups of plants ters, one on the Mesozoic Marine Revolution, all the or animals radiate rapidly. The PCM provide numerous great events in the oceans as life “speeded up,” one on the approaches to test rates of evolution on well‐dated evo- Cretaceous Terrestrial Revolution, when the diversifica- lutionary trees to identify times of unusually high rates of tion of flowering plants changed ecosystems on land for- evolution, responses of life to external events, and key ever, and one on the evolution of oceans and climates. characters that might contribute to a group’s success. This means the book can be used for introductory classes, Finally, in paleobiology itself, the science of bringing but the theme can be either “the major steps in evolution fossils to life, new engineering methods can be applied from origins to humans” or “history of the diversity of to ancient shells and bones to test their strength charac- life.” The new chapters allow us to keep the strong focus teristics and capabilities. You want to know the bite on vertebrate evolution, but to strengthen the more geo- force of Tyrannosaurus rex? Paleobiologists can calcu- logical and ecological themes of the evolution of oceans, late that. How fast did Brontosaurus run? We can test climates, and marine life. that too. Could an ammonite shell withstand 100 pounds The genesis of this edition may require a brief com- of compression force from a predator? We can work that ment. Richard Cowen has labored valiantly on his own, one out. presenting five editions of the History of Life from 1990 What has happened since 1990 is that paleobiology to 2013. When the call came from Wiley for a sixth edi- has become a testable science in all its aspects – know- tion, he turned to the paleontology group at the University ing the shape of evolution, dating fossils, describing of Bristol, UK, to help. Richard’s idea is that we keep the ancient crises and their effects, identifying whether a shape and flavor of the book but freely update it. Mike group radiated explosively and why, and testing what Benton took the lead and his colleagues in Bristol, Tom extinct organisms could do. No longer can we simply sit Williams, John Cunningham, Davide Pisani, Jakob around speculating … “I think T. rex was purple with Vinther, Phil Donoghue, Daniela Schmidt, Andy Fraass, green spots,” “No, surely it was blue with yellow stripes,” Christine Janis, Emily Rayfield, and Tom Davies (listed “I think the dinosaurs died out because they were just roughly in order of their chapters), accepted the chal- too big and stupid.” When you hear these kinds of state- lenge with enthusiasm. Adrian Lister at the Natural ments, the answer is, “How can we test that?” If it History Museum, London, provided extensive help with cannot be tested, it’s best left aside for the moment until the Ice Ages chapter. We decided collectively also to pool we can find a way to determine color or reasons for any earnings from the sales of the book and donate them extinction. to the Bob Savage Memorial Fund which supports stu- As Richard Cowen noted in his introduction to the dent research – some of which appears in this book! fifth edition, “The challenge of teaching paleontology, and the challenge of writing a book like this, is to present To Our Teaching Colleagues a complex story in a way that is simple enough to grasp, yet true enough to real events that it paints a reasonable picture of what happened and why. I believe it can be The course for which this book was written serves four done and done so that you can learn enough to appreci- audiences at the same time: it is an introduction to pale- ate what’s going on in current research projects.” ontology; it is a “general education” course to introduce Combining the excitement of the story – all the new nonspecialists to science and scientific thought; it pro- fossils, the exotic lands and fossil sites, the big events vides an overview of the interactions of environmental they tell us about – with a true feel of how that knowl- change and biodiversity; and it can serve as an introduc- edge has been debated and tested is a tricky task. We tion to the history of life to biologists who know a lot have attempted to tell the story while also giving a flavor about the present and little about the past. Therefore, the of the hard work behind each discovery. style and language of this book are aimed at accessibility.