In Pursuit of Early Mammals

Zofia Kielan-Jaworowska

Description

Mammals from the age of dinosaurs

In Pursuit of Early Mammals presents the history of the mammals that lived during the Mesozoic era, the time when dinosaurs ruled the Earth, and describes their origins, anatomy, systematics, paleobiology, and distribution. It also tells the story of the author, a world-renowned specialist on these animals, and the other prominent paleontologists who have studied them. Zofia Kielan-Jaworowska was the first woman to lead large-scale paleontological expeditions, including eight to the Gobi Desert in Mongolia, which brought back important collections of dinosaur, early mammal, and other fossils. She shares the difficulties and pleasures encountered in finding rare fossils and describes the changing views on early mammals made possible by these discoveries.

Preface
1. Introduction
2. Methods: Collecting Materials and Establishing Relationships
3. Paleontological Exploration of Mongolia by American, Japanese, Soviet and Russian Expeditions
4. Polish-Mongolian Expeditions, and the Nomadic Expedition, 2002
5. Origins of Mammals and the Earliest Representatives of Mammaliaforms and Mammals
6. Haramiyidans and Probable Related Forms
7. Docodontans
8. Eutriconodontans
9. Monotremes and the Issue of Australosphenida and Boreosphenida
10. Multituberculates and Gondwanatherians
11. "Symmetrodontans"
12. "Eupantotherians" and the Origin of Pseudotribosphenic Molars
13. Tribotheria, Matatheria, and the Issue of Deltatheroida
14. Eutherian and Placental Mammals
15. Paleobiology of Mammaliaforms and Early Mammals
16. Diversification of Mammaliaforms and Mesozoic Mammals: A Summary
Bibliography
Index

Sujets

• Sciences de la nature
• Biologie
• Life Sciences
• Mammals
• Sciences et techniques
• Biology
• Zoology
• Paleontology
• Mammal
• Evolution
• 454 Life Sciences
• Science

Informations

• Publié par: Indiana University Press
• Date de parution: 12 juillet 2013
• Nombre de lectures: 0
• EAN13: 9780253008244
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

In Pursuit of Early Mammals
IN PURSUIT OF EARLY MAMMALS
Zofia Kielan-Jaworowska
Life of the Past James O. Farlow, editor
Indiana University Press Bloomington Indianapolis
This book is a publication of
Indiana University Press Office of Scholarly Publishing Herman B Wells Library 350 1320 East 10th Street Bloomington, Indiana 47405 USA
iupress.indiana.edu
Telephone orders 800-842-6796 Fax orders 812-855-7931
2013 by Zofia Kielan-Jaworowska
All rights reserved
No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and recording, or by any information storage and retrieval system, without permission in writing from the publisher. The Association of American University Presses Resolution on Permissions constitutes the only exception to this prohibition.
The paper used in this publication meets the minimum requirements of the American National Standard for Information Sciences-Permanence of Paper for Printed Library Materials, ANSI Z39.48-1992.
Manufactured in the United States of America
Library of Congress Cataloging-in-Publication Data
Kielan-Jaworowska, Zofia. In pursuit of early mammals / Zofia Kielan-Jaworowska. pages cm.-(Life of the past) ISBN 978-0-253-00817-6 (cl : alk. paper)-ISBN 978-0-253-00824-4 (eb) 1. Paleontology-Mesozoic. 2. Mammals, Fossil. 3. Archaeological expeditions. I. Title. QE731.K54 2013 569-dc23
2012047303
1 2 3 4 5 18 17 16 15 14 13
I dedicate this book to the memory of my husband ZBIGNIEW JAWOROWSKI
(17 October 1927-12 November 2011)
Contents
Foreword
Preface
Acknowledgments
List of Institutional Abbreviations

1. Introduction
2. Methods: Collecting Materials and Establishing Relationships
3. Paleontological Exploration of Mongolia by American, Japanese, Soviet, and Russian Expeditions, including the Mongolian Academy/American Museum and Mongolia/Japan Joint Expeditions
4. The Polish-Mongolian Paleontological Expeditions, 1963-1971, and the Nomadic Expedition, 2002
5. Origins of Mammals and the Earliest Representatives of Mammaliaforms and Mammals
6. Haramiyidans and Probable Related Forms
7. Docodontans
8. Eutriconodontans
9. Monotremes and the Issue of Australosphenida and Tribosphenida
10. Multituberculates and Gondwanatherians
11. Symmetrodontans
12. Eupantotherians and the Origin of Tribosphenic and Pseudotribosphenic Molars
13. Tribotheria, Metatheria, and the Issue of the Deltatheroida
14. Eutherian and Placental Mammals
15. Aspects of Paleobiology of Mammaliaforms and Early Mammals
16. Diversification of Mammaliaforms and Mesozoic Mammals: A Summary

References
Index
Foreword
SINCE THE DEMISE OF NON-AVIAN DINOSAURS SOME 65 MILLION years ago, modern mammals-that is to say, marsupials, placentals, and monotremes-have become conspicuous, diverse elements of Earth s biota. But the family tree that includes mammals and their nearest relatives (mammaliaforms, in technical parlance) is far more deeply rooted in time, extending back to perhaps 220 million years ago. Clearly, then, the varieties known from the age of mammals that followed dinosaur extinctions represent only the uppermost boughs of what is increasingly being revealed as a bushy, complex tree.
Knowledge of early mammalian history-the lower part of that tree-has long been limited by a fossil record that is disappointingly sparse, even to those paleontologists who set a low bar when it comes to basic data. Fossils are generally tiny, fragmentary (most species are known by isolated teeth or jaw fragments), and incredibly hard to find. The dawn of discovery took place in the late nineteenth century. Synthetic study of these fossils, almost all from Britain and the western United States, was completed in the 1920s by the great evolutionary biologist G. G. Simpson. It was also at this time that the first mammalian skulls of Mesozoic age were discovered in Cretaceous rocks of Mongolia. Simpson recognized the existence of various now-extinct Mesozoic mammal lineages, as well as representatives (or, it now appears, relatives) of modern groups. But this early period of discovery and study raised fundamental questions that could not be addressed with the existing record. Did the egg-laying platypus and echidnas of Australia and New Guinea, for example, independently evolve from reptilian precursors? Meaningful biological interpretation also remained beyond reach: about all one could say is that early mammals were generally small, shrew-like creatures that probably preferred an insect-based diet. (The stereotype has persisted: as this book shows, it is erroneous.) Early mammal history had emerged from total darkness, but remained in the shadows.
The situation has changed profoundly in recent decades. A new period of fossil discovery began in the mid-twentieth century and its pace has quickened to a dizzying rate. A number of species are now known by breathtakingly complete specimens, some even preserving remnants of fur. Long-term, dedicated effort has resulted in the collection of large samples and comprehensive assemblages for some areas and time intervals. Informative fossils have been recovered from most major landmasses, and though substantial gaps in the record persist, much of the Mesozoic time scale has been sampled. And, of course, many new species and some major groups have been discovered, revealing previously unimagined diversity among early mammals: some hopped; others climbed, burrowed, swam, and even glided; at least one species fed on young dinosaurs. Amazingly, a venom-delivery system (in the form of an ankle spur as seen in living monotremes) seems to have been widespread among early groups. This explosive growth in basic data-the fossils themselves-has been coupled with important conceptual, technological, and methodological advances. Ultrahigh-resolution X-ray computed tomography, for example, has made accessible a wealth of new anatomical information. Comparative studies of new fossils show that early mammals played a broad array of biological roles. Key evolutionary transformations, such as the appearance of the multi-function molar, expansion of the brain, and the development of the characteristic three-boned middle ear, are now relatively well understood. Notably, it appears that each of these transformations took place more than once in mammalian history. The fossil record now provides reasonable time constraints on the divergence of modern lineages-constraints that are consistent with estimates derived from molecular studies based on living species. Perhaps most significantly, new means of reconstructing genealogy have provided the outlines and many details of the mammalian tree mentioned earlier, and there is now general consensus about placement of many of the major branches on that tree.
Now, finally, we know enough about Mesozoic mammals that a general book on the subject is not only possible, but urgently needed. This volume serves that purpose. The author, Zofia Kielan-Jaworowska, has been at the vanguard of the field for half a century. In the following pages she recounts the origin, evolutionary history, relationships, and biology of early mammals-largely from firsthand experience in both field and lab. More than that, she tells us about the people who have discovered and studied the fossils unearthed during the modern era. No field program has contributed more to-or symbolizes better-this modern era of discovery than the now-legendary Polish-Mongolian Expeditions (1963-1971), which Kielan-Jaworowska herself led. Here she gives us a compelling personal account of those remarkable journeys-the logistics, hazards, setbacks, and successes, together with a behind-the-scenes tour of subsequent research that shed important new light on early mammals.
Where do we go from here? We now have a rough outline of mammalian history during the Mesozoic. That outline is still very much a work in progress. Simple logic tells us that state-of-the-art is, after all, just a state; and the history of science provides us with ample evidence that states of understanding are ephemeral. Despite all that we have learned in the past half-century, the data remain scant: significant as they are, the advances reported on these pages represent approximately charted islands of a barely explored sea. The study of Mesozoic mammals is ripe with opportunity. Single new specimens can overturn decades of established wisdom. Fundamental new interpretation and understanding will depend on the discovery of new fossils and the adoption of new perspectives. May this book inspire the next generation of paleontologists to set out in pursuit of early mammals!
Richard L. Cifelli
Preface
THIS BOOK PRESENTS A HISTORY OF MESOZOIC MAMMALS AS SEEN through the eyes of people studying them, including myself and the colleagues with whom I had a chance to work over the years. The Mesozoic Era was the time when dinosaurs ruled the earth. Mammals living with them were mostly small, and it seemed for a long time that they did not play an important role in Mesozoic faunas. But in recent decades our view has changed. Thanks to new methods of searching for them, and new expeditions organized to countries from which they previously were unknown, or hardly known, new collections of Mesozoic mammals have been gathered and studied.
In contrast to my earlier book Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure , which I wrote in collaboration with Richard L. Cifelli and Zhe-Xi Luo (2004), in which we used the traditional definition of Mammalia including extinct groups outside the crown group, in the present book I follow the high-rank systematics of Rowe (1988) and McKenna and Bell (1997). The crown group, as defined by Jeffries (1989), consists of the living members of a monophyletic group, their latest living ancestor, and all descendants of that ancestor. Mammalia are thus restricted to the