Neogene Paleontology of the Manonga Valley, Tanzania A Window into the Evolutionary History of East Africa TOPICS IN GEOBIOLOGY Series Editors: Neil H. Landman, American Museum of Natural History, New York, New York Douglas S. Jones, University of Florida, Gainesville, Florida Current volumes in this series: Volume 2 ANIMAL-SEDIMENT RELATIONS The Biogenic Alteration of Sediments Edited by Peter L. McCall and Michael J. S. Tevesz Volume 3 BIOTIC INTERACTIONS IN RECENT AND FOSSIL BENTHIC COMMUNITIES Edited by Michael J. S. Tevesz and Peter L. McCall Volume 4 THE GREAT AMERICAN BIOTIC INTERCHANGE Edited by Francis G. Stehli and S. David Webb Volume 5 MAGNETITE BIOMINERALIZATION AND MAGNETORECEPTION IN ORGANISMS A New Biomagnetism Edited by Joseph L. Kirschvink, Douglas S. Jones and Bruce J. MacFadden Volume 6 NAUTILUS The Biology and Paleobiology of a Living Fossil Edited by W. Bruce Saunders and Neil H. Landman Volume 7 HETEROCHRONY IN EVOLUTION A Multidisciplinary Approach Edited by Michael L. McKinney Volume 8 GALApAGOS MARINE INVERTEBRATES Taxonomy, Biogeography, and Evolution in Darwin's Islands Edited by Matthew J. James Volume 9 TAPHONOMY Releasing the Data Locked in the Fossil Record Edited by Peter A. Allison and Derek E. G. Briggs Volume 10 ORIGIN AND EARLY EVOLUTION OF THE METAZOA Edited by Jere H. Lipps and Philip W. Signor Volume 11 ORGANIC GEOCHEMISTRY Principles and Applications Edited by Michael H. Engel and Stephen A. Macko Volume 12 THE TERTIARY RECORD OF RODENTS IN NORTH AMERICA William Korth Volume 13 AMMONOID PALEOBIOLOGY Edited by Neil H. Landman, Kazushige Tanabe, and Richard Arnold Davis Volume 14 NEOGENE PALEONTOLOGY OF THE MANONGA VALLEY, TANZANIA A Window into the Evolutionary History of East Africa Edited by Terry Harrison A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher. Neogene Paleontology of the Manonga Valley, Tanzania A Window into the Evolutionary History of East Africa Edited by Terry Harrison New York University New York, New York Springer Science+Business Media, LLC Library of Congress Cataloging-in-Publication Data Neogene paleontology of the Manonga Valley. Tanzania a window into the evolutionary history of East Africa I edited by Terry Harrison. p. cm. -- (Topics in geobiology ; v. 14) Includes bibliographical references and index. 1. Paleontology--Neogene. 2. Animals. Fossil--Tanzania--Manonga Valley. 3. Geology. Stratigraphic--Neogene. 4. Geology--Tanzania- -Manonga Valley. I. Harrison. Terry. II. Series. QE738.5.N46 1997 560' . 1786'0967827--dc21 97-14542 CIP ISBN 978-1-4419-3265-5 ISBN 978-1-4757-2683-1 (eBook) DOI 10.1007/978-1-4757-2683-1 © 1997 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1997. Softcover reprint ofthe hardcover 1st edition 1997 http://www.plenum.com All rights reserved 10 9 8 7 6 5 4 3 2 1 No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher To the people of Tanzania who welcomed me into their country and shared their knowledge and wisdom Contributors Miranda Armour-Chelu Department of Anatomy, College of Medicine, Howard University, Washington, D.C. 20059 Eric Baker Department of Anthropology, Paleoanthropology Laboratory, New York University, New York, New York 10003 Raymond L. Bernor College of Medicine, Department of Anatomy, Howard University, Washington, D.C. 20059 Laura C. Bishop Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, United Kingdom Achilles Gautier Universiteit Gent, Vakgroep Geologie en Bodemkunde, Labo­ ratorium voor Paleontologie, B-9000 Gent, Belgium Alan W. Gentry c/o Department of Palaeontology, Natural History Museum, London SW7 5BD, United Kingdom Terry Harrison Department of Anthropology, Paleoanthropology Laboratory, New York University, New York, New York 10003 Michael 1. Mbago Director General, National Museums of Tanzania, Dar es Salaam, Tanzania Medard Mutakyahwa Department of Geology, University of Dar es Salaam, Dar es Salaam, Tanzania William J. Sanders Museum of Paleontology, University of Michigan, Ann Arbor, Michigan 48109 Kathlyn M. Stewart Paleobiology Section, Canadian Museum of Nature, Ottawa, Ontario K1P 6P4, Canada Dirk Van Damme Universiteit Gent, Vakgroep Geologie en Bodemkunde, Labo­ ratorium voor Paleontologie, B-9000, Gent, Belgium Jacques Verniers Universiteit Gent, Vakgroep Geologie en Bodemkunde, Labo­ ratorium voor Paleontologie, B-9000, Gent, Belgium Alisa J. Winkler Shuler Museum of Paleontology, Southern Methodist Univer­ sity, Dallas, Texas 75275 vii Preface In spite of the dedication and resourcefulness shown by paleontologists and paleoanthropologists over the past seventy years in their quest to find new fossil hominids, it is clear that, in the enterprise of reconstructing the evolutionary history of humans (and other mammals), we still have much to accomplish. It is true that we have made significant advances, with the help of some remarkable fossil discoveries, in documenting the main phylogenetic strands, but we know very little about the detailed anatomy or paleobiology of these lineages, or about the critical events that led to their divergence and subsequent evolutionary changes. Our image of the early evolutionary history of our own species is based on a montage of snapshots obtained from fleeting glimpses of the phylogenetic tree as seen through a few narrow temporal and spatial windows provided us by the fossil record. If our objective is not simply to fill in the missing gaps, and thereby document the configuration of the major branches of the human evolu­ tionary tree, but rather to gain some real insight into early hominid diversity in space and time, and to explain this diversity in terms of the complexity of ecological, geographic, and evolutionary factors that produced it, then we need a broader perspective. We should strive to improve the quality (not just the quantity) of the hominid fossil record, so that it includes a wider geographic coverage and a finer temporal resolution. In order to achieve this objective, the search for new paleontological sites in Africa, and elsewhere, must be considered as a high priority. Paleontology is inherently a risky business, with no guarantee of returns on one's investment, but given the right balance of effort, perseverance, funding, and good fortune, significant advances in our knowledge of human evolution can be made. Exciting new finds of Plio-Pleistocene hominids from Ethiopia, Eritrea, Kenya, Malawi, and Chad provide tangible evidence of such successes. The people of Tanzania are justifiably proud of the fact that some of the most important fossil and archaeological finds pertaining to the earliest stages of human evolution have been discovered in their country. Olduvai Gorge and Laetoli are famous throughout the world, and fossil discoveries at these sites have made a significant contribution toward helping to piece together the evolutionary history of humankind over the past four million years. Today, Tanzania is celebrated internationally as a leading center for paleoanthropologi­ cal studies. Even so, only three sites in Tanzania have yielded the remains of early fossil hominids, Olduvai Gorge, Laetoli, and Peninj, all located in the Serengeti Plains in the northeastern part of the country. This limited distribution is primarily a consequence of geological factors. The sites cluster at the southern ix x Preface extremity of the Gregory Rift. where the eastern branch of the East African Rift valley splays out around the margin of the resistant Tanganyika shield. The rift valley. and its associated volcanism. provides an ideal geological setting for the preservation and recovery of fossils. Indeed. almost all of the spectacular early hominid fossil finds in East Africa are from sites located within the Eastern Rift. However. another significant factor is that the sites in northern Tanzania are easily accessible. especially from Kenya. The full paleontological potential of Olduvai Gorge was not realized until the 1950s. when Louis and Mary Leakey were able to intensify their explorations from their base in Nairobi. Today it is relatively easy for expeditions and tourist buses to reach Olduvai Gorge. but when Louis Leakey began his pioneering work there in the early 1930s. it was a major logistical problem. Louis Leakey's initial paleontological experiences in the southern part of Tanzania give some indication of the past difficulties and dangers involved in mounting major expeditions to the more remote regions of the country. In 1924. Louis Leakey took part in an ill-fated expedition to the Jurassic site of Tendaguru. where W. E. Cutler. the leader of the expedition. succumbed to blackwater fever. Our knowledge of the paleontology and archae­ ology of most of Tanzania is quite limited. especially when compared with that of neighboring Kenya. which has been much more extensively explored. Geolo­ gists interested in locating economically important minerals and deposits have surveyed much ofTanzania. and in the process they have reported finding further sites with fossils. but very few paleontologists or archaeologists have ever visited these sites. As a consequence, a large number