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WATER REPTILES OF THE PAST AND PRESENT THE UNIVEESITY OF CHICAGO PRESS CHICAGO, ILLINOIS Agrttts THE CAMBRIDGE UNIVERSITY PRESS LONDON AND EDINBURGH THE MARUZEN-KABUSHIKI-KAISHA TOKYO, OSAKA, KYOTO KARL W. HIERSEMANN LEIPZIG THE BAKER & TAYLOR COMPANY NEW YORK WATER REPTILES OF THE PAST AND PRESENT BY Samuel Wendell Williston Professor of Paleontology in the University of Chicago 3) 6 I THE UNIVERSITY OF CHICAGO PRESS CHICAGO, ILLINOIS 4 Copyright 1914 by The University of Chicago All Rights Reserved Published October 191 Composed and Printed By The University of Chicago Press Chicago, Illinois, U.S.A. : PREFACE It was just forty years ago that the writer of these lines, then an assistant of his beloved teacher, the late Professor B. F. Mudge, dug from the chalk rocks of the Great Plains his first specimens of water reptiles, mosasaurs and plesiosaurs. To the youthful col- lector, whose first glimpse of ancient vertebrate life had been the result of accident, these specimens opened up a new world and diverted the course of his life. They were rudely collected, after the way of those times, for modern methods were impracticable with the rifle in one hand and the pick in the other. Nor was much known in those days of these or other ancient creatures, for the science of vertebrate paleontology was yet very young. There were few students of fossil vertebrates—Leidy, Cope, and Marsh were the only ones in the United States—and but few collectors, of whom the writer alone survives. Those broken and incomplete specimens, now preserved in the museum of Yale University, will best explain why this little book was written. The author offers it, so far as lies within him, as an authoritative and accurate account of some of the creatures of earlier ages which sought new opportunities by going down from the land into the water. So far as possible he has endeavored to make the text understandable, and, he hopes, of interest also, to the non-scientific reader. He will not apologize for such scientific terms as remain, since only by their use can precision be attained there are no common English equivalents for them. The reader will find their explanations in the chapter on the skeleton of reptiles, and especially in the illustrations. The author has had the opportunity during recent years of critically studying nearly all the reptiles described in the following pages, but, if that were the only source of his information, the accounts of many would have been meager. He has endeavored, briefly at least, to mention the names of all those to whom we are chiefly indebted for our knowledge, but in such a work as this it is manifestly impracticable to give due credit to every one. vi WATER REPTILES OF THE PAST AND PRESENT To the friends who have been of assistance in various ways he tenders his sincere thanks: to Professor E. Fraas for photographs and the kind permission to reproduce some of his excellent illus- trations; to Dr. Dreverman, of the Senckenberg Museum, for several excellent photographs for reproduction or restoration; to Dr. Hauff , of Holzmaden, for an excellent photograph of an ichthyosaur; to Dr. H. F. Osborn, of the American Museum, for permission to reproduce the spirited restoration of ichthyosaurs drawn by Mr. Knight; to Professors Schuchert and Lull, and Dr. Wieland, of Yale University; to Dr. Hay and Mr. Gilmore, of the National Museum, to Mr. Barnum Brown and Dr. McGregor, of the American Museum, and to Professor Merriam, of the University of California, for photographs and other favors. Samuel W. Williston University of Chicago July, 1914 CONTENTS CHAPTER PAGE I. Introduction . i II. Classification of Reptiles 13 III. The Skeleton of Reptiles . -19 IV. The Age of Reptiles 44 V. Adaptation of Land Reptiles to Life in the Water . 59 VI. Order Sauropterygia . 73 Plesiosauria. Nothosauria. VII. Order Anomodontia .102 Lystrosaurus. VIII. Order Ichthyosauria 107 IX. Order Proganosauria 126 Mesosaurus. X. Order Protorosauria 132 Protorosaurus. Pleurosaurus. XL Order Squamata 138 Lizards. Mosasaurs. Snakes. XII. Order Thalattosauria 171 XIII. Order Rhynchocephalia 176 Choristodera. XIV. Order Parasuchia 184 Phytosauria. XV. Order Crocodilia 194 Eusuchia. Mesosuchia. Thalattosuchia. XVI. Order Chelonia 216 Side-necked Turtles. Snapping Turtles. Fresh-water or Marsh Tortoises. Land Tortoises. Sea-Turtles. Ancient Sea-Turtles. Leather-back Marine Turtles. River Turtles. vii — CHAPTER I INTRODUCTION In most persons the word reptile incites only feelings of disgust and abhorrence; to many it means a serpent, a cold, gliding, treacherous, and venomous creature shunning sunlight and always ready to poison. Our repugnance to serpents is so much a part of our instincts, or at least of our early education, that we are prone to impute to all crawling creatures those evil propensities which in reality only a very few possess. Were there no venomous serpents—and there are but two other venomous reptiles known we should doubtless see much to admire in those animals now so commonly despised; because a few dozen kinds, like the rattle- snakes, copperheads, and cobras, protect themselves in ways not unlike those used by man to protect himself, we unjustly abhor the thousands of other kinds, most of which are not only innocent of all offense toward man, but are often useful to him. There are now living upon the earth more than four thousand kinds or species of cold-blooded animals which we call reptiles, all of which are easily distinguishable into four principal groups : the serpents and lizards, the crocodiles, the turtles, and the tuatera. Their habits and forms are very diverse, but they all possess in common certain structural characters which sharply distinguish them from all other living creatures. A reptile may be tersely defined as a cold-blooded, backboned animal which breathes air throughout life. And yet, it is not quite certain that this defini- tion is strictly correct when applied to all the reptiles of the past, since it has been believed that certain extinct ones may have been warm-blooded. By this definition, short as it is, we at once exclude a large number of cold-blooded, air-breathing, backboned animals which were formerly included by scientific men among the true reptiles, and even yet are popularly often so included—the amphibians or batrachians. These animals, now almost wholly represented by the despised toads, frogs, and salamanders, were, 2 WATER REPTILES OF THE PAST AND PRESENT very long ago, among the rulers of the land, of great size and extraordinary forms. But they have dwindled away, both in size and in numbers, till only a comparatively few of their descendants are left, none of them more than two or three feet in length, and all of them sluggish in disposition and of inoffensive habits. While we may speak of the amphibians as air-breathing, they are, with few exceptions, water-breathers during the earlier part of their existence. Some may pass their whole lives as water-breathers, while a few begin to breathe air as soon as hatched from the egg; but these are the marked exceptions. In many respects the internal structure of the amphibians of the present time is widely different from that of reptiles, though there can be no doubt that the early amphibian ancestors of the modern toads, frogs, and salamanders were also the ancestors of all living and extinct reptiles, and it is a fact that the living amphib- ians differ more from some of the ancient ones than those early amphibians did from their contemporary reptiles. Discoveries in recent years have bridged over nearly all the essential differ- ences between the two classes so completely that many forms can- not be classified unless one has their nearly complete skeletons. We know that some of the oldest amphibians, belonging to the great division called Stegocephalia, were really water-breathers during a part of their lives, because distinct impressions of their branchiae, or water-breathing organs, have been discovered in the rocks with their skeletal remains, but we are not at all sure that some of the more highly developed kinds were not air-breathers from the time they left the egg; indeed, we rather suspect that such was the case. We are also now quite certain that, from some of the early extinct reptiles—the immediate forbears probably of the great dinosaurs—the class of birds arose, since the structural relation- ships between birds and reptiles are almost as close as those between reptiles and amphibians. Huxley believed that the great class of mammals arose directly from the amphibians, and there are some zoologists even yet who think that he was right. But paleontologists are now quite sure that they were evolved from a group of primitive reptiles, known INTRODUCTION 3 Theriodontia quite sure because chiefly from Africa, called the ; nearly all the connecting links between the two classes have already been discovered—to such an extent, indeed, that really nothing distinctive of either class is left save the presence or absence of the peculiar bone called the quadrate, the bone with which the lower jaw articulates in birds and reptiles; and certain elemental parts of the lower jaw itself. And even these bones, in certain mammal- like reptiles, had become mere vestiges. Even the double condyle of the mammal skull, with which the vertebrae articulate, so like those of the amphibian skull that Huxley based his belief of the amphibian origin of the mammals chiefly upon it, has now been found in certain reptiles. Warm-bloodedness, one of the diagnostic characters of birds and mammals, is not really very important, since it must have arisen in these two classes independently, and we may easily conceive that the earliest mammals were cold- blooded or that the immediate ancestors of the mammals were warm-blooded.

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