Sabertooth

Sabertooth

Life of the Past James O. Farlow, editor

SABER TOOTH

Mauricio Antón

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Indiana University Press

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© 2013 by Mauricio Antón

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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 China

Library of Congress Cataloging-in-Publication Data

Antón, Mauricio.

Sabertooth / Mauricio Antón.

pages cm. – (Life of the past)

Includes bibliographical references and index.

ISBN 978-0-253-01042-1 (cl : alk.

paper) – ISBN 978-0-253-01049-0 (ebook)

1. Saber-toothed tigers. I. Title.

QE882.C15A55 2013

569’.7 – dc23

2013001962

1  2  3  4  5  18  17  16  15  14  13

FOR MY FAMILY AND IN MEMORY OF ALAN TURNER.

AND WHAT SHOULDER AND WHAT ART

COULD TWIST THE SINEWS OF THY HEART?

AND WHEN THY HEART BEGAN TO BEAT,

WHAT DREAD HAND AND WHAT DREAD FEET?

WILLIAM BLAKE, THE TYGER

Foreword

Preface

Acknowledgments

1. What Is a Sabertooth?

2. The Ecology of Sabertooths

3. A Who’s Who of Sabertoothed Predators

4. Sabertooths as Living Predators

5. Extinctions

Bibliography

Index

FOR THE PAST THIRTY-FIVE YEARS I HAVE HAD THE PRIVILEGE OF spending time in the company of Africa’s charismatic big cats – the lions, leopards, and cheetahs that my wife, Angie, and I have come to know as individuals, recording their lives in words, drawings, and photographs in the Masai Mara in Kenya, the northern extension of Tanzania’s great Serengeti National Park.

The Mara-Serengeti is an ancient land: there are rocks at the heart of the Serengeti that are more than three billion years old. Standing on a hilltop overlooking the vastness of the Serengeti’s short-grass plains during the rainy season, you can witness a Pleistocene vision, the land awash with animals. Hundreds of thousands of wildebeest and zebras, tens of thousands of gazelles, and hundreds of elands and ostriches share the mineral rich grasslands. Dotted among them you can pick out the sloping backs and powerful forequarters of spotted hyenas as they amble along, the herds parting and closing again as the predators pass through or begin to hunt. Prides of lions rest up in the shade of granite outcrops known as kopjes that emerge like castles from a sea of grass. Somewhere a leopard lies recumbent along the wide limb of a giant fig tree, while a cheetah perches sphinx-like on a termite mound, looking for a gazelle fawn to chase down. This is the last place on earth where you can see scenes of such abundance, yet it’s only a fragment of our planet’s past animal glories.

The fossil record allows us a glimpse of other times and other creatures equally as fascinating and awe inspiring as anything seen today, times when there were many more members of the cat family searching for prey among wild landscapes across the globe.

We are mesmerized by predators. There is a mixture of awe and fear, a reminder at some primal level of the time 2 million years ago when our ancestors emerged from the forest edges into the sunlight of the African savannahs, scavenging and killing prey for themselves. To do this they had to find ways of competing with the great cats and hyenas of that epoch. Little wonder, then, that we fear the large predators for their power while admiring them for their strength and courage. This ambiguous relationship between hunter and hunted is echoed in the hauntingly beautiful cave art of Lascaux and Chauvet in Europe – an artistic tradition that Mauricio Antón so admirably continues with the artwork in his fascinating and informative Sabertooth. It takes a skilled observer with imagination to bring the past to life.

Who hasn’t felt a thrill and fascination at the mention of sabertooths? Cartographers of ancient times inscribed here be dragons on early maps, conjuring up vivid images of giant reptiles living deep in the heart of Africa, in the same way that sabertooth tigers (as they were sometimes referred to) were the highlight of the Boys Own magazines and comics of my childhood. Something for youngsters to fantasize about; ripping adventures played out in the wilds of Africa and beyond.

I first came across Mauricio Antón’s eye-catching draftsmanship in a copy of his The Big Cats and Their Fossil Relatives when Angie and I were researching a series of books on Africa’s big cats to accompany the popular television series Big Cat Diary. Mauricio’s beautifully crafted drawings and paintings allowed us to step back in time to a very different era. If a love of the African savannahs has driven our own passion for wilderness and adventure, then imagine the thrill of taking a safari through the Pleistocence landscape of a million years ago – or further back still, to the Miocene of 20 million years ago that heralded the advent of the extinct relatives of our modern big cats.

The world of fossils and prehistoric life must by its very nature remain part of our imagination – something ancient and to a degree unfathomable. It takes the vision of an artist and the dogged determination of a detective, combined with the highest understanding of our current knowledge of anatomy and animal behavior, to conjure up illustrations that are both believable and awe inspiring. This is Mauricio’s gift, and I particularly love his panoramas: colorful renditions of complete landscapes that suggest a dynamic and living storyboard of creatures and events from tens of thousands of years ago – millions, in some cases.

The largest and most famous of the sabertooth cats is Smilodon, an animal that was larger and more powerful than the largest living tiger and that roamed the American landscapes as recently as ten thousand years ago. Its saber teeth – curved, dagger-like canines – have been the source of speculation and inquiry into why such fearsome yet fragile weapons evolved and how they were used, questions that Mauricio Antón attempts to answer in this book.

The natural world we live in is constantly evolving, molded by climate, soil, and competition between species through the process of natural selection. The wonder of the wild animals, plants, and trees we see today are its creation, as are the remnants of times past in the form of fossils. From these ancient fragments and a thorough knowledge of all these processes combined with the findings of the very latest DNA technology, Mauricio is able to take us on a journey of exploration to rival any modern-day safari.

Jonathan Scott

SABERTOOTH CATS ARE AMONG THE MOST POPULAR OF PREHISTORIC animals, yet surprisingly little information about them is available for the curious layperson. One particular genus, Smilodon, has exerted an intense fascination since its discovery, and it has been featured in children’s books, cartoons and films. But there were actually many other genera and species of sabertooth cats, coming in different shapes and sizes. To define them in a single sentence, sabertooth cats are extinct members of the extant cat family (Felidae), and thus close relatives of our living cats but different from them in several ways – most notably in having spectacularly enlarged upper canines, but also in a series of anatomical features that point to a different hunting style.

Sabertooth cats are not the only subject of this book, because they were not the only sabertooths to exist. As used by paleontologists, the term sabertooth designates also several kinds of extinct predators that were not cats, or even close relatives of them, but that shared some or all of the distinctive anatomical adaptations of sabertooth cats. Nimravids, barbourofelids, thylacosmilids – each of these obscure names designates a wholly different family of predators that developed remarkably similar morphologies. Some were no taller than a domestic cat, others were larger than a lion, and some would have looked weird indeed. This book intends to review that diversity of sabertooths, cats or otherwise.

For specialists, sabertooths have posed some of the most baffling enigmas of paleontology, and there is still much to learn. What did sabertooths look like? Some reconstructions depict them essentially as lions or tigers with oversized fangs, while others show them as bizarre creatures not resembling cats, or any other living carnivores for that matter. How did they use their spectacular canine teeth? There have been many hypotheses about the predatory habits of sabertooths, ranging from theories that they would be utterly unable to hunt and would have been scavengers exclusively to those that they were capable of hyperviolent stabbing. And why did they finally go extinct? Some experts thought that sabertooths were victims of an irreversible trend, in which their canines became so big and cumbersome over the generations that they ultimately caused the demise of the last species. Others believed that sabertooths specialized in hunting gigantic, thick-skinned prey, and that at the end of the last ice age when many of those monsters vanished, so did the sabertooths – leaving the world to the faster normal cats, which were better adapted to hunt fleet-footed prey like horses and antelope. We will probably never be able to answer these questions with total certainty. But over the last few decades a lot of exciting research has been carried out that certainly is taking us closer to the answers, and it has already suggested that all of the old hypotheses reviewed above were, in all likelihood, wrong.

Continuing studies will reveal ever more details about the evolution and biology of sabertooths, but unless we manage to master time travel, one thing will always remain true: they will be visible to us only as dry fossils or as reconstructions of one kind or another. As with all fossil species, a sort of visual translation is needed before we can see them as living creatures, and this process of restoration is also an essential part of the contents of this book. Reconstruction is an art and a science, and it requires a familiarity with anatomy and a fastidious attention to detail. Some people might believe that since we will never know with absolute accuracy what extinct animals looked like, a rough approximation should be enough. But we don’t perceive living animals in an approximate way – at least when we are at all interested in them: horse or dog enthusiasts, for example, know how important precise morphology is in order to define their favorite breeds; and wild animals look beautiful to us because of their unique, precise shapes and proportions. Subtlety is all-important when picturing a living creature, as wildlife artists have known since the times of the Altamira or Chauvet cave paintings. All fossil animals are one step removed from direct observation, so it is essential that we strive for total accuracy in the process of reconstruction, even though – or precisely because – it is an ultimately unattainable goal. In the case of sabertooth cats, careful attention to anatomical detail is the only way to get a realistic idea (one not based on subjective preconceptions) of how similar or how different they were from their modern relatives, the extant big cats.

A strong commitment to science has been the hallmark of good paleoart since its beginnings, and many paleontologists also have a great capacity for visual observation and considerable drawing abilities. The founding father of vertebrate paleontology, G. Cuvier (1769–1832), was a competent draftsman, and around the beginning of the nineteenth century he produced remarkable restorations of some of the fossil species that he described for science. Unfortunately, he did not publish those drawings, which remained forgotten in the archives of the Muséum national d’Histoire naturelle in Paris until they were rediscovered in the late twentieth century (Rudwick 1992). If Cuvier had been less modest (or cautious) about his artwork, maybe modern paleoart would have matured decades earlier than it did, but almost a century had to pass before the greatest pioneer of this discipline brought it to fruition: C. Knight. Besides his solid training as an artist (and an abundant talent), Knight was an accomplished anatomist and a keen observer of nature, and his collaboration with the great paleontologists of his time – especially H. F. Osborn – was a process of constant discovery (Milner 2012). More to the point of this book’s subject matter, Knight’s collaboration with paleontologists led him to create restorations of sabertooths that have stood the test of time in a remarkable way, thanks to the rigor and beautiful simplicity of his working methodology.

In this book, I hope the reconstructions will serve as both a tool of study and a way to make available to readers the diversity and depth of anatomical detail that the fossil record of sabertooths has revealed to scientists after many decades of research. Fossils are recovered only through strenuous fieldwork, followed by patient cleaning and preparation of the specimens and endless hours of analysis, measurement, and the processing of CT scan images, or whatever technique is used to extract information from the fossilized remains. Should the knowledge so laboriously amassed remain buried in academic publications, beyond the reach of sincerely curious lay readers? I don’t think so.

Beyond the interest that any group of fossil animals may have for both specialists and laypersons, the study of extinct creatures and their adaptations gives us a renewed appreciation of how nature works. Furthermore, paleontology provides a perception of the temporal dimension of life that today is more necessary than ever. In our ancestors’ distant past, when hominids were just one more kind of mammals completely subject to the laws of ecology, the perception of nature from their own spatial and temporal scale was all that our ancestors required to meet their everyday needs. Even today this perception (an immersion in nature) greatly increases our well-being. But, having become collectively the most powerful biological agent on earth (still subject to the laws of ecology but in a way that the individual human, sheltered by technology, easily fails to notice), we badly need the opposite view as well: to see our home planet with perspective, to perceive its fragility and realize how crucial our present actions will be for the long-term future of the biosphere – and of our species.

Seeing the earth from space has provided such a perspective in spatial terms, and paleontology does something comparable in temporal terms, showing us that extant biodiversity, with all its fascinating detail, is just one frame in the long film of the evolution of life. Each species, which may seem static to us, is actually the result of the accumulated changes of countless species before, and it may be destined to keep changing or to go extinct, but that fate should not depend on human actions. It is deeply unethical for us to consider cutting through that evolutionary process without remorse as if our species collectively were a blind, impersonal agent of change, something comparable to the asteroid that killed off the dinosaurs 65 million years ago.

The long history of coevolution, as exemplified by the mutual influence between predator and prey through time, stresses the interdependence of all parts of the global ecosystem. We must ensure that the delicate machinery of the biosphere will keep functioning for the coming generations (if only to provide a habitable world for them), and that life will continue to evolve in the long term as close as possible to the way it would have done without our intervention. In a truly sustainable future, big cats and other carnivores, not human pressures, should be the main agents checking the populations of wild herbivores, wherever those are left. Predation is not only a drama to add emotion to nature documentaries: like it or not, it is an essential part of the way the web of life works.

Like modern big cats, sabertooths are iconic creatures, and this makes them excellent ambassadors of past biodiversity, as the emotional response they stir in us helps to heighten our interest in the details of their adaptations. Indeed, with their development of strikingly similar morphologies in so many independent lineages, they offer one of the best and most engaging examples of the laws of evolution in action. Additionally, there is a final, almost tragic quality to their extinction that helps us understand how wonderful it is that whenever we want to know more about the behavior and adaptations of lions or tigers, all we have to do is go where they live and observe them (at least, that will remain a possibility for a while). In contrast, we can throw all our scientific tools at sabertooths, yet there is an enormous amount about them that we will never know for sure. Nevertheless, in the process of studying them, we can learn much about the workings of predation in general, and our approach to the conservation of today’s top predators should benefit from such insights.

Biodiversity is subject to time, and it thus changes, but it feeds our minds in a way that nothing else can. In fact, we should defend it not only as a material resource but also as the source of our sanity. Science and art, now more than ever, should naturally celebrate that diversity, and sabertooths are particularly fascinating examples of it.

MY INTEREST IN SABERTOOTHS BEGAN WHEN I WAS EIGHT YEARS OLD and lived in Valladolid, in Spain. I came across a copy of The Golden Book Encyclopedia of Natural Science, and leafing through the section on fossils, I found an illustration by Rudolph Zallinger that depicted a scene in the Pleistocene of Rancho la Brea, in California. There, a sabertooth was seen attacking a mammoth that had been trapped in the asphalt, while dire wolves and giant condors approached from the distance. That image had a striking effect on me: rather than just looking at an illustration, it was like being sucked through a time portal and taken back to a legendary era crowded with powerful beasts. And most important, this was no imaginary land with fantastic creatures, but a depiction of animals and landscapes that really existed. So I must credit the artwork of Zallinger for planting the seed of a fascination that lasts to this day.

Years later, as a teenager living in Caracas, I found in the school library a copy of The Land and Wildlife of South America, which included a chapter about extinct mammals illustrated by Jay Matternes. The paintings were fascinating in themselves, but what impressed me most was a double-page spread with a collection of sketches showing how Matternes had created his reconstruction of the sabertooth marsupial Thylacosmilus. This was a revelation as important as Zallinger’s La Brea scene. Here I found not only information about a kind of sabertooth whose existence I had not suspected, but also a description of a whole process of acquisition and interpretation of scientific information in order to depict an extinct animal. I owe to Matternes the conviction that began to take shape in me around that time: that was the kind of work I would like to do if I could.

In spite of that fascination with paleontological subjects, I chose to get a formal artistic training, but later on I found that I needed to learn much more about paleontology in order to provide a solid base for my reconstructions of past life. That need opened a whole new chapter of learning, and I have been fortunate to meet a lot of people who have provided invaluable help along the way.

I first met Alan Turner in 1991, when I was a hopeful young paleo-artist looking for advice and collaboration. Alan was visiting Madrid on his way to a scientific conference in northern Spain, and he was invited to give a lecture at the Museo de Ciencias Naturales. I quickly put together a portfolio of my reconstructions to show him at the end of the talk, and to my great happiness he was instantly supportive of my work. During the few days of his stay we met several times, and we agreed to start work on our first collaboration, which would become the book The Big Cats and their Fossil Relatives–in several ways a senior companion to this volume. Many academic articles and books done together would follow, as well as a great friendship. We shared not only scientific discussions, but also family vacations and even flamenco evenings. This book would have been simply impossible without the long years of collaboration with Alan, from whom I learnt much about paleontology, about communicating science, and about many other things – including how a sense of humor can be the best and sometimes the only way to coexist with the contradictions of life. Alan passed away untimely, in early 2012, but he remains very much alive in the memory of his many friends and collaborators.

Also in 1991 I met Richard Tedford at the American Museum of Natural History, and starting with that first visit and in the years that followed he was always a source of help and inspiration. He opened for me that treasure trove of sabertooth fossils that are the collections of vertebrate paleontology of the American Museum of Natural History, and he freely shared his wisdom about carnivore evolution. All who knew Tedford agree that in addition to all his qualities as a scientist, he was the epitome of a gentleman.

In the early 1990s I started a fruitful correspondence with the Swiss paleontologist Gérard de Beaumont, who was already retired but more than willing to share his views about sabertooth evolution in a series of long manuscript letters that I now treasure (that was before I entered the e-mail era, although it may now be difficult to imagine that such a time ever existed). I count myself fortunate to have shared his knowledge in his late years. Also in the early 1990s I got in touch with the French paleontologist Leonard Ginsburg, who shared not only his knowledge but also the amazing fossil material housed at the Muséum national d’Histoire naturelle, in Paris, including some then-unpublished specimens that helped me get a clearer picture of early felid evolution. Leonard was a monumental figure in French paleontology, and his scientific legacy is enormous.

Also in the early 1990s Roland Ballesio from the University of Lyon, the author of a groundbreaking monograph about the European scimitar-tooth cat Homotherium and a leading expert in carnivore evolution, was kind enough to share many insights into the adaptations of sabertooths.

My longest collaboration in the study of carnivore evolution is with Jorge Morales from the Museo de Ciencias Naturales, in Madrid, a collaboration that continues to this day. Back in 1987 I approached him with a great fascination about fossil carnivores and an even greater ignorance of the subject, but he encouraged me to visit his laboratory whenever I wanted and virtually opened up the world of paleontology for me. He supported both my interest in paleoart, getting me in touch with patrons who would provide me with professional assignments, and in research, giving me the fundamentals of vertebrate paleontology and showing me the way into the academic literature. Later, when the incredible fossil site of Cerro Batallones, the star of European sabertooth paleontology, was discovered near Madrid, Jorge invited me to be there from the beginning and to experience firsthand the discovery of the best fossil sample ever found of Miocene sabertooths.

Manuel Salesa, who under Jorge’s direction wrote his PhD dissertation on the anatomy and evolution of the sabertooth felid Promegantereon from Batallones, has become my closest collaborator in the study of sabertooths. It has been my privilege to share Manuel’s research since his