 INTRODUCTORY AND EXPLAINATORY OF ANIMALS OF THE PAST. Recording by Jeffrey Smith, New Orleans, Louisiana. ANIMALS OF THE PAST, by Frederick A. Lucas. INTRODUCTORY AND EXPLAINATORY At the present time, the interest in the ancient life of this earth is greater than ever before, and very considerable sums of money are being expended to dispatch carefully planned expeditions to various parts of the world systematically to gather the fossil remains of the animals of the past. That this interest is not merely confined to a few scientific men, but is shared by the general public, is shown by the numerous articles, including many telegrams in the columns of the daily papers. The object of this book is to tell some of the interesting facts concerning a few of the better known or more remarkable of these extinct inhabitants of the ancient world. Also, if possible, to ease the strain on these venerable animals caused by stretching them so often beyond their due proportions. The book is admittedly somewhat on the lines of Mr. Hutchinson's extinct monsters and creatures of other days, but it is hoped that it may be considered with books, as with boats, a good plan to build after a good model. The information scattered through these pages has been derived from varied sources. Some has, of necessity, been taken from standard books, a part has been gathered in the course of museum work and official correspondence. For much the author is indebted to his personal friends, and for a part he is under obligations to friends he has never met, who have kindly responded to his inquiries. The endeavor has been conscientiously made to exclude all misinformation. It is nevertheless entirely probable that some mistakes may have crept in, and due apology for these is hereby made beforehand. The author expects to be taken to task for the use of scientific names, and the reader may perhaps sympathize with the old lady who said that the discovery of all these strange animals did not surprise her so much as the fact that anyone should know their names when they were found. The real trouble is that there are no common names for these animals. Then, too, people who call for easier names do not stop to reflect that in many cases the scientific names are no harder than others, simply less familiar, and when domesticated they cease to be hard. They are witness mammoth, elephant, rhinoceros, giraffe, boa constrictor, all of which are scientific names. And if, for example, we were to call the hierocotherium a hyrax beast, it would not be a name but a description, and not a bit more intelligible. Again, it is impossible to indicate the period at which these creatures lived without using the scientific term for it, Jurassic, Eocene, Pliocene, as the case may be, because there is no other way of doing it. Some readers will doubtless feel disappointed because they are not told how many years ago these animals lived. The question is often asked, how long ago did this or that animal live? But when the least estimate puts the age of the earth at only ten million years, while the longest makes it six billion, it does seem as if it were hardly worthwhile to name any figures. Even when we get well toward the present period, we find the time that has elapsed since the beginning of the Jurassic, when the dinosaurs held carnival, variously put at from fifteen million to six million years, while from the beginning of the Eocene, when the mammals began to gain the supremacy, until now, the figures vary from three million to five million years. So the question of age will be left for the reader to settle to his or her satisfaction. The restorations of extinct animals may be considered as giving as accurate representations of these creatures as it is possible to make. They were either drawn by Mr. Knight, whose name is guaranteed that they are of the highest quality, or by Mr. Gleason, with the aid of Mr. Knight's criticism. That they are infallibly correct is out of the question, for, as Dr. Woodward writes in the preface to extinct monsters, restorations are ever liable to emmendation, and the present will certainly prove no exception to the rule. As a striking instance of this, it was found necessary at the last moment to change the figure of Hesperarnus, the original lifelike portrait proving to be incorrect in attitude, a fact that would have long escaped detection, but for the Pan-American exposition. The connection between the two is explained on page 76. However, the reader may rest assured that these restorations are infinitely more nearly correct than many figures of living animals that have appeared within the last twenty-five years, and are even now doing duty. The endeavor has been made to indicate at the end of each chapter the museums in which the best examples of the animals described may be seen, and also some book or article in which further information may be obtained. As this book is intended for the general reader, references to purely technical articles have, so far as possible, been avoided, and none in foreign languages mentioned. For more important works of reference on the subject of paleontology, the reader may consult a manual of paleontology by Alan Nicholson and R. Leidecker, a work in two volumes dealing with invertebrates, vertebrates, and plants, or a textbook of paleontology by Carl von Zittle, English edition, only the first volume of which has so far been published. An admirable book on the vertebrates is Outlines of Vertebrate Paleontology by Arthur Smith Woodward. It is to be understood that these are not at all popular in their scope but intended for students who are already well advanced in the study of zoology. End of Introductory and Explanatory Chapter 1 of Animals of the Past by Frederick Lucas This LibriVox recording is in the public domain. Recording by Jeffrey Smith. Fossils and how they are formed. How of a thousand snakes each one was changed into a coil of stone. Fossils are the remains or even the indications of animals and plants that have, through natural agencies, been buried in the earth and preserved for long periods of time. This may seem a rather meager definition, but it is a difficult matter to frame one that will be at once brief, exact, and comprehensive. Fossils are not necessarily the remains of extinct animals or plants. Neither are they of necessity objects that have become petrified or turned into stone. Bones of the Great Ock and Ritina, which are quite extinct, would hardly be considered as fossils. While the bones of many species of animals, still living, would properly come in that category, having long ago been buried by natural causes and often been changed into stone. And yet it is not essential for a specimen to have had its animal matter replaced by some mineral in order that it may be classed as a fossil. For the Siberian mammoths, found entombed in ice, are very properly spoken of as fossils, although the flesh of at least one of these animals was so fresh that it was eaten. Likewise, the mammoth tusks brought to market are termed fossil ivory, although differing but little from the tusks of modern elephants. Many fossils indeed merit their popular appellation of petrifications because they have been changed into stone by the slow removal of the animal or vegetable matter present and its replacement by some mineral, usually silica, or some form of lime. But it is necessary to include indications of plantar animals in the above definition, because some of the best fossils may be merely impressions of plantar animals and no portion of the objects themselves. And yet, as we shall see, some of our most important information has been gathered from these same imprints. Nearly all our knowledge of the plants that flourished in the past is based on the impressions of their leaves left on the soft mud or smooth sand that later on hardened into enduring stone. Such, too, are the trails of creeping and crawling things, tasks of the burrows of worms and the many footprints of the reptiles, great and small, that crept along the shore or stalked beside the waters of the ancient seas. The creatures themselves have passed away, their massive bones even are lost, but the prints of their feet are as plain today as when they were first made. Many a crustacean, too, is known solely or mostly by the cast of its shell, the hard parts having completely vanished and the existence of birds in some formations is revealed merely by the casts of their eggs. And these natural casts must be included in the category of fossils. Impressions of vertebrates may indeed be almost as good as actual skeletons, as in the case of some fishes, where the fine mud in which they were buried has become changed to a rock, rivaling porcelain in texture. The bones have either dissolved away or shattered into dust at the splitting of the rock, but the imprint of each little fin-ray and every thread-like bone is as clearly defined as it would have been in a freshly prepared skeleton. So fine indeed may have been the mud, and so quiet for the time being the waters of the ancient sea or lake, that not only have prints of bones and leaves been found, but those of feathers and of the skin of some reptiles, and even of such soft and delicate objects as jellyfishes. But for these we should have little positive knowledge of the outward appearance of the creatures of the past, and to them we are occasionally indebted for the solution of some moot point in their anatomy. The reader may possibly wonder why it is that fossils are not more abundant. Why, of the vast majority of animals that have dwelt upon the earth since it became fit for the habitation of living beings, not a trace remains. This too, when some objects, the tusks of the mammoth, for example, have been sufficiently well preserved to form staple articles of commerce at the present time, so that the carved handle of my lady's parasol may have formed part of some animal that flourished at the very dawn of the human race, and been gazed upon by her grandfather a thousand times removed. The answer to this query is that unless the conditions were such as to preserve at least the hard parts of any creature from immediate decay, there was small probability of its becoming fossilized. These conditions are that the objects must be protected from the air, and practically the only way that this happens in nature is by having them covered with water, or at least buried in wet ground. If an animal dies on dry land, where its bones lie exposed to the summer's sun and rain, and the winter's frost and snow, it does not take these destructive agencies long to reduce the bones to powder. In the rare event of a climate devoid of rain, mere changes of temperature by producing expansion and contraction will sooner or later cause a bone to crack and crumble. Usually too the work of the elements is aided by that of animals and plants. Everyone has seen a dog make way with a pretty good sized bone, and the hyena has still greater capabilities in that line. And ever since vertebrate life began, there have been carnivorous animals of some kind to play the role of bone destroyers. Even were there no carnivores, there were probably then, as now, rats and mice aplenty, and few suspect the havoc small rodents may play with a bone for the grease it contains, or merely for the sake of exercising their teeth. Now and then we come upon a fossil bone, long since turned into stone, on which are the marks of the little cutting teeth of field mice, put there long, long ago, and yet looking as fresh as if made only last week. These little beasts, however, are indirect rather than direct agents in the destruction of bones by gnawing off the outer layers and thus permitting the more ready entrance of air and water. Plants as a rule begin their work after an object has become partly or entirely buried in the soil, when the tiny rootlets find their way into fissures, and expanding as they grow act like so many little wedges to force it asunder. Thus on dry land there is small opportunity for a bone to become a fossil. But if a creature so perishes that its body is swept into the ocean or one of its estuaries settles to the muddy bottom of a lake or is caught on the sandy shoals of some river, the chances are good that its bones will be preserved. They are poorest in the ocean, for unless the body drifts far out and settles down in quiet waters, the waves pound the bones to pieces with stones or scour them away with sand, while marine worms may pierce them with burrows or echinoderms cut holes for their habitations. There are more enemies to a bone than one might imagine. Suppose, however, that some animal has sunk in the depths of a quiet lake, where the wash of the waves upon the shore wears the sand or rock into mud so fine that it floats out into still water and settles there as gently as dew upon the grass. Little by little the bones are covered by a deposit that fills every groove and pore, preserving the mark of every ridge and furrow. And while this may take long, it is merely a matter of time and favorable circumstance to bury the bones as deeply as one might wish. Scarce a reader of these lines, but at some time has cast anchor in some quiet pond and pulled it up, thickly covered with sticky mud, whose existence would hardly be suspected from the sparkling waters and pebbly shores. If instead of a lake our animal had gone to the bottom of some estuary into which poured a river turbid with mud, the process of entombment would have been still more rapid, while had the creature been engulfed in quick sand it would have been the quickest method of all. And just such accidents did take place in the early days of the earth as well as now. At least two examples of the great dinosaur Thespesias have been found with the bones all in place, the thigh bones still in their sockets and the ossified tendons running along the backbone as they did in life. This would hardly have happened had not the body been surrounded and supported so that every part was held in place and not crushed, and it is difficult to see any better agency for this than burial in quick sand. If such an event as we have been supposing took place in a part of the globe where the land was gradually sinking and the crust of the earth is ever rising and falling, the mud and sand would keep on accumulating until an enormously thick layer was formed. The lime or silica contained in the water would tend to cement the particles of mud and grains of sand into a solid mass while the process would be aided by the pressure of the overlying sediment the heat created by this pressure and that derived from the earth beneath. During this process the animal matter of bones or other objects would disappear and its place be taken by lime or silica and thus would be formed a layer of rock containing fossils. The exact manner in which this replacement is affected and in which the chemical and mechanical changes occur is very far from being definitely known, especially as the process of fossilization must at times have been very complicated. In the case of fossil wood greater changes have taken place than in the fossilization of bone, for there is not merely an infiltration of the specimen but a complete replacement of the original vegetable by mineral matter, the interior of the cells being first filled with silica and their walls replaced later on. So completely and minutely may this change occur that under the microscope the very cellular structure of the wood is visible and as this varies according to the species it is possible by microscopic examination to determine the relationship of trees in cases where nothing but fragments of the trunk remain. The process of fossilization is at best a slow one and soft substances such as flesh or even horn decay too rapidly for it to take place so that all accounts of petrified bodies human or otherwise are either based on deliberate frauds or are the result of a very erroneous misinterpretation of facts. That the impression or cast of a body might be formed in nature somewhat as castes have been made of those who perished at Pompeii is true but so far no authentic case of the kind has come to light and the reader is quite justified in disbelieving any report of a petrified man. Natural castes of such hard bodies as shells are common formed by the dissolving away of the original shell after it had become enclosed in mud or even after this had changed to stone and the filling up of this space by the filtering in of water charged with lime or silica which is there deposited often in crystalline form. In this way too are formed castes of eggs of reptiles and birds so perfect that it is possible to form a pretty accurate opinion as to the group to which they belong. Sometimes it happens that shells or other small objects embedded in limestone have been dissolved and replaced by silica and in such cases it is possible to eat away the enveloping rock with acid and leave the solidified castes. By this method specimens of shells, corals, and bryozoans are obtained of almost lace-like delicacy and as perfect as if only yesterday gathered at the seashore. Castes of the interior of shells, showing many details of structure, are common and anyone who has seen clams dug will understand how they are formed by the entrance of mud into the empty shell. Castes of the kernels of nuts are formed in much the same way and Professor E. H. Barber has thus described the probable manner in which this was done. When the nuts were dropped into the water of the ancient lake the kernel rotted away but the shell, being tough and hard, would probably last for years under favorable circumstances. Throughout the marls and clays of the badlands of South Dakota there is a large amount of potash. This is dissolved by water and then acts upon quartz carrying it away in solution. This would find its way by infiltration into the interior of the nut. At the same time with this process carrying lime carbonate in solution was going on so that doubtless the stone kernels consisting of pretty nearly equal parts of lime and silica were deposited within the nuts. These kernels of course became hard and flinty in time and capable of resisting almost any amount of weathering. Not so the organic shell. This eventually would decay away and so leave the filling or kernel of calcedonian lime. Footnote. Right here is the weak spot in Professor Barber's explanation and an illustration of our lack of knowledge for it is difficult to see why the more enduring husk should not have become mineralized equally with the cavity within. End of footnote. Fossil leaves are nothing but fine casts made in natural molds and all have seen the first stages in their formation as they watched the leaves sailing to the ground be covered by mud or sand at the next rain or dropping into the water where sooner or later they sink as we may see them at the bottom of any quiet woodland spring. Impressions of leaves are among the early examples of color printing for they are frequently of a darker or even different tint from that of the surrounding rock this being caused by the carbonization of vegetable matter or to its action on iron that may have been present in the soil or water. Besides complete mineralization or petrification there are numerous cases of incomplete or semi fossilization where modern objects still retaining their phosphate of lime and some animal matter even are found buried in rock. This takes place when water containing carbonate of lime silica or sometimes iron flows over beds of sand cementing the grains into solid but not dense rock and at the same time penetrating and uniting with it such things as chance to be buried. In this way was formed the fossil man of Guadalupe West Indies a skeleton of a modern carob lying in recent concretionary limestone together with shells of existing species and fragments of pottery. In a similar way too human remains in parts of Florida have through the infiltration of water charged with iron become partially converted into limonite iron ore and yet we know that these bones have been buried within quite recent times. Sometimes we hear of springs or waters that turn things into stone but these tales are quite incorrect. Waters there are like the celebrated hot springs of Auvergne France containing so much carbonate of lime in solution that it is readily deposited on objects placed therein, coating them more or less thickly according to the length of time they are allowed to remain. This however is merely an incrustation not extending into the objects. In a similar way the precipitation of solid material from waters of this description forms the porous rock known as tufa and this often encloses moss, twigs and other substances that are in no way to be classed with fossils. But some streams flowing over limestone rocks take up considerable carbonate of lime and this may be deposited in water-soaked logs replacing more or less of the woody tissue and thus really partially changing the wood into stone. The very rocks themselves may consist largely of fossils. Chalk for example is mainly made up of the disintegrated shells of simple marine animals called foraminifers and the beautiful flint-like skeletons of other small creatures termed radiolarians. Minute as they are have contributed extensively to the formation of some strata. Even after an object has become fossilized it is far from certain that it will remain in good condition until found while the chance of its being found at all is exceedingly small. When we remember that it is only here and there that nature has made the contents of the rocks accessible by turning the strata on edge heaving them into cliffs or furrowing them with valleys and canyons we realize what a vast number of pages of the fossil record must remain not only unread but unseen. The wonder is not that we know so little of the history of the past but that we have learned so much for not only is nature careless in keeping the records, preserving them mostly in scattered fragments but after they have been laid away and sealed up in the rocks they are subject to many accidents. Some specimens get badly flattened by the weight of subsequently deposited strata. Others are cracked and twisted by the movements of the rocks during periods of upheaval or subsidence and when at last they are brought to the surface the same sun and rain, snow and frost from which they once escaped are ready to renew the attack and crumble even the hard stone to fragments. Such very briefly are some of the methods by which fossils may be formed such are some of the accidents by which they may be destroyed. But this description must be taken as a mere outline and as applying mainly to vertebrates or backboneed animals since it is with them that we shall have to deal. It may however show why it is that fossils are not more plentiful, why we have more hints of the existence of many animals and why myriads of creatures may have flourished and passed away without so much as leaving a trace of their presence behind. References A very valuable and interesting article by Dr. Charles A. White entitled The Relation of Biology to Geological Investigation will be found in the report of the United States National Museum for 1892. This comprises a series of essays on the nature and scientific uses of fossil remains, their origin, relative chronological value and other questions pertaining to them. The United States National Museum has published a pamphlet Part K, Bulletin 39, Containing Directions for Collecting and Preparing Fossils by Charles Shukert, and another Part B, Bulletin 39, Collecting Recent and Fossil Plants by F. H. Nolton. End of Chapter 1. Chapter 2 of Animals of the Past by Frederick Lucas. This LibriVox recording is in the public domain. Recording by Jeffrey Smith. The earliest known vertebrates. We are the ancients of the earth and in the morning of the times. There is a universal and perfectly natural desire for information, which in ourselves we term thirst for knowledge, and in others call curiosity, that makes mankind desire to know how everything began, and causes much speculation as to how it all will end. This may take the form of a wish to know how a millionaire made his first ten cents, or it may lead to the questions, what is the oldest animal? Or what is the first known member of the great group of backboneed animals at whose head man has placed himself? And what did this, our primeval and many times removed ancestor, look like? The question is one that has ever been full of interest for naturalists, and nature has been interrogated in various ways in the hope that she might be persuaded to yield a satisfactory answer. The most direct way has been that of tracing back the history of animal life by means of fossil remains. But beyond a certain point this method cannot go since, for reasons stated in various places in these pages, the soft bodies of primitive animals are not preserved. To supplement this work the embryologist has studied the early stages of animals, as their development throws a sidelight on their past history. And finally there is the study of the varied forms of invertebrates, some of which have proved to be like vertebrates in part of their structure, while others have been revealed as vertebrates in disguise. So far these various methods have yielded various answers, or the replies, like those of the Delphic Oracle, have been variously interpreted so that vertebrates are considered by some to have descended from the worms, while others have found their beginnings in some animal allied to the king crab. Every student of genealogy knows only too well how difficult a matter it is to trace a family pedigree back a few centuries, how soon the family names become changed, the line of dissent obscure, and how soon gaps appear whose filling in requires much patient research. How much more difficult must it be then to trace the pedigree of a race that extends not over centuries, but thousands of centuries? How wide must be some of the gaps, how very different may the founders of the family be from their descendants? The words old and ancient that we use so often in speaking of fossils appeal to us somewhat vaguely, for we speak of the ancient civilizations of Greece and Rome and call a family old that can show a pedigree running back four or five hundred years, when such as these are but affairs of yesterday compared with even recent fossils. Perhaps we may better appreciate the meaning of these words by recalling that, since the dawn of vertebrate life, sufficient of the earth's surface has been worn away and washed into the sea to form where the strata piled directly one upon the other fifteen or twenty miles of rock. This, of course, is the sum total of sedimentary rocks, for such a thickness as this is not to be found at any one locality. Because, during the various ups and downs that this world of ours has met with, those portions that chanced to be out of water would receive no deposit of mud or sand, and hence bear no corresponding stratum of rock. The reader may think that there is a great deal of difference between fifteen and twenty miles, but this liberal margin is due to the difficulty of measuring the thickness of the rocks, and in Europe the sum of the measurable strata is much greater than in North America. The earliest traces of animal life are found deeper still, beneath something like eighteen to twenty-five miles of rock, while below this level are the strata in which dwelt the earliest living things, organisms so small and simple that no trace of their existence has been left, and we infer that they were there because any given group starts in a modest way with small and simple individuals. At the bottom, then, of twenty miles of rocks, the seeker for the progenitor of the great family of backboneed animals finds the scant remains of fish-like animals that the cautious naturalist who is much given to hedging terms not vertebrates but pre-vertebrates or the forerunners of backboneed animals. The earliest of these consist of small bony plates and traces of a cartilaginous backbone from the lower Solerian of Colorado, believed to represent relatives of chimera and species related to those better-known forms, holoticius and osteolepis, which occur in higher strata. There are certainly indications of vertebrate life, but the remains are so imperfect that little more can be said regarding them, and this is also true of the small conical teeth which occur in the lower Solerian of St. Petersburg and are thought to be the teeth of some animal like the lamprey. A little higher up in the rocks, though not in the scale of life, in the lower, old red sandstone of England, are found more numerous and better preserved specimens of another little fish-like creature, rarely if ever exceeding two inches in length, and also related, probably, to the hagfishes and lampreys that live today. These early vertebrates are not only small, but they were cartilaginous, so that it was essential for their preservation that they should be buried in soft mud as soon as possible after death. Even if this took place, they were later on submitted to the pressure of some miles of overlying rock, until, in some cases, their remains have been pressed out thinner than a sheet of paper, and so thoroughly incorporated into the surrounding stone that it is no easy matter to trace their shadowy outlines. With such drawbacks as these to contend with, it can scarcely be wondered at that, while some naturalists believe these little creatures to be related to the lamprey, others consider that they belong to a perfectly distinct group of animals, and others still think it possible that they may be the larval or early stages of larger and better developed forms. Still higher up we come upon the abundant remains of numerous small fish-like animals, more or less completely clad in bony armor, indicating that they lived in troublous times when there was literally a fight for existence, and only such as were well-armed or well-protected could hope to survive. A parallel case exists today in some of the rivers of South America, where the little catfishes would possibly be eaten out of existence, but for the fact that they are covered, some of them very completely, with plate-like armor that enables them to defy their enemies, or renders them such poor eating as not to be worth the taking. The arrangement of the plates or scales in the living Loricaria is very suggestive of the series of bony rings covering the body of the ancient Cephalaspus, only the latter, so far as we know, had no side fins, but the creatures are in no wise related, and the similarity is in appearance only. Ptericthus, the wingfish, was another small quaint armor-clad creature, whose fossilized remains were taken for those of a crab, and once described as belonging to a beetle. Certainly the buckler of this fish, which is the part most often preserved with its jointed bony arms, looks to the untrained eye far more like some strange crustacean than a fish, and even naturalists have pictured the animal as crawling over the bare sands by means of those same arms. These fishes and their allies were once the dominant type of life, and must have abounded in favored localities, for in places are great deposits of their protective shields, jumbled together in a confused mass, and saved that they have hardened into stone, lying just as they were washed up on the ancient beach ages ago. How abundant they were may be gathered from the fact that it is believed their bodies helped consolidate portions of the strata of the English old red sandstone. Says Mr. Hutchinson speaking of the cateness flagstones, they owe their peculiar tenacity and durability to the dead fishes that rotted in their midst, while yet they were only soft mud. For just as a plaster cast boiled in oil becomes thereby denser and more durable, so the oily and other matter coming from decomposing fish operated on the surrounding sand or mud, so as to make it more compact. It may not be easy to explain how it came to pass that fishes dwelling in salt water, as these undoubtedly did, were thus deposited in great numbers, but we may now and then see how deposits of freshwater fishes may have been formed. When rivers flowing through a stretch of level country are swollen during the spring floods, they overflow their banks, often carrying along large numbers of fishes. As the water subsides, these may be caught in shallow pools that soon dry up, leaving the fishes to perish, and every year the Illinois Game Association rescues from the backwaters quantities of bass that would otherwise be lost. Mr. F. S. Webster has recorded an instance that came under his observation in Texas, where thousands of garpikes trapped in a lake formed by an overflow of the Rio Grande had been, by the drying up of this lake, pinned into a pool about 75 feet long by 25 feet wide. The fish were literally packed together like sardines, layer upon layer, and a shot fired into the pool would set the entire mass in motion, the larger guards as they dashed about casting the smaller fry into the air, a score at a time. Mr. Webster estimates that there must have been not less than 700 or 800 fish in the pool, from a foot and a half up to seven feet in length, every one of which perished a little later. In addition to the fish in the pond, hundreds of those that had died previously lay about in every direction, and one can readily imagine what a fish bed this would have made had the occurrence taken place in the past. From the better preserved specimens that do now and then turn up, we are able to obtain a very exact idea of the construction of the bony quiris by which ptericthus and its American cousin were protected, and to make a pretty accurate reconstruction of the entire animal. These primitive fishes had mouths, for eating is a necessity, but these mouths were not associated with true jaws, for the two do not, as might be supposed, necessarily go together. Neither did these animals possess hard backbones, and while ptericthus and its relatives had arms or fins, the hard parts of these were not on the inside but on the outside, so that the limb was more like the leg of a crab than the fin of a fish. And this is among the reasons why some naturalists have been led to conclude that vertebrates may have developed from crustaceans. Teraspis, another of these little armored pre-vertebrates, had a less complicated covering and looked very much like a small fish, with its four parts caught in an elongate clam shell. The fishes that we have so far been considering, orphans of the past they might be termed as they have no living relatives, were little fellows. But their immediate successors, preserved in the Devonian strata, particularly of North America, were the giants of those days, termed, from their size and presumably fierce appearance, titanicthus and dinicthus, and are related to a fish, serratatus still living in Australia. We know practically nothing of the external appearance of these fishes, great and fierce though they may have been, with powerful jaws and armored heads, for they had no bony skeleton, as if they devoted their energies to preying upon their neighbors, rather than to internal improvements. They attained a length of ten to eighteen feet, with a gape in the large species called titanicthus, of four feet, and such a fish might well be capable of devouring anything known to have lived at that early date. Succeeding these, in Carboniferous times, came a host of shark-like creatures, known mainly from their teeth and spines, for their skeletons were of cartilage, and belonging to types that have mostly perished, giving place to others better adapted to the changed conditions wrought by time. Almost the only living relative of these early fishes was a little shark, known as the Port Jackson shark, living in Australian waters. Like the old sharks this one has a spine in front of his back fins, and like them he fortunately has a mouth full of diversely shaped teeth. Fortunately because through their aid we are enabled to form some idea of the manner in which some of the teeth found scattered through the rocks were arranged. For the teeth were not planted in sockets as they are in higher animals, but simply rested on the jaws, from which they readily became detached when decomposition set in after death. To complicate matters the teeth in different parts of the jaws were often so unlike one another that when found separately they would hardly be suspected of having belonged to the same animal. Besides teeth these fishes, for purposes of offense and defense, were usually armed with spines, sometimes of considerable size and strength, and often elaborately grooved and sculptured. As the soft parts perished the teeth and spines were left to be scattered by waves and currents, a tooth here, another there, and a spine somewhere else. So it has often happened that being found separately two or three quite different names have been given to one and the same animal. Now and then some specimen comes to light that escaped the thousand and one accidents to which such things were exposed and that not only shows the teeth and spines but the faint imprint of the body and fins as well. And from such rare examples we learn just what teeth and spines go with one another and sometimes find that one fish has received names enough for an entire school. These ancient sharks were not the large and powerful fishes that we have today, these came upon the scene later, but mostly fishes of small size and, as indicated by their spines, fitted quite as much for defense as offense. Their rise was rapid and in their turn they became the masters of the world, spreading in great numbers through the waters that covered the face of the earth. But their supremacy was of short duration for they declined in numbers even during the Carboniferous period and later dwindled almost to extinction. And while sharks again increased they never reached their former abundance and the species that arose were swift predatory forms better fitted for the struggle for existence. References The early fishes make but little show in a museum both on account of their small size and the conditions under which they have been preserved. The Museum of Comparative Zoology has a large collection of these ancient vertebrates and there is a considerable number of fine teeth and spines of Carboniferous sharks in the United States National Museum. Hugh Miller's The Old Red Sandstone contains some charming descriptions of his discoveries of Teryctis and related forms and this book will ever remain a classic. End of Chapter 2 Chapter 3 of Animals of the Past by Frederick Lucas This LibriVox recording is in the public domain. Recording by Jeffrey Smith Impressions of the Past The Weird Polymsist Old and Vast Wherein Thou Hidest the Spectral Past The Reverend H. N. Hutchinson commences one of his interesting books with Emerson's saying that everything in nature is engaged in writing its own history. And as this remark cannot be improved on it may well stand at the head of a chapter dealing with the footprints of the creatures of yore left on the sands of the seashore, the mud of a long vanished lake-bottom, or the shrunken bed of some water-course. Not only have creatures that walked left a record of their progress, but the worms that burrowed in the sand, the shellfish that trailed over the mud when the tide was low, the stranded crab as he scuttled back to the sea, each and all left some mark to tell of their former presence. Even the rain that fell and the very wind that blew sometimes recorded the direction whence they came, and we may read in the rocks also accounts of freshets sweeping down with turbid waters and of long periods of drought when the land was parched by lakes and rivers shrank beneath the burning sun. All these things have been told and retold. But as there are many who have not read Mr. Hutchinson's books and to whom Buckland is quite unknown it may be excusable to add something to what has already been said in the first chapter of these impressions of the past. The very earliest suggestion we have of the presence of animal life upon this globe is in the form of certain long dark streaks below the Cambrian of England, considered to be traces of the burrows of worms that were filled with fine mud, and while this interpretation may be wrong there is, on the other hand, no reason why it may not be correct. Plant and animal life must have had very lowly beginnings, and it is not at all probable that we shall find any trace of the simple and minute forms with which they started, though we should not be surprised at finding hints of the presence of living creatures below the strata in which their remains are actually known to occur. Footnote. Within the last few years what are believed to be indications of bacteria that have been described from Carboniferous rocks? Naturally such announcements must be accepted with great caution. For while there is no reason why this may not be true it is much more probable that definite evidence of the effects of bacteria on plants should be found than that these simple single-celled organisms should themselves have been detected. End of footnote. Worm burrows, to be sure, are hardly footprints, but tracks are found in Cambrian rocks just above the strata in which the supposed burrows occur, and from that time onward there are tracks aplenty, for they have been made wherever the conditions were favourable ever since animals began to walk. All that was needed was a medium in which impressions could be made and so filled that there was imperfect adhesion between mold and matrix. Thus we find them formed, not only by the seashore in sands alternately dry and covered, but by the riverside in shallow water or even on land where tracks might be left in soft or moist earth to which wind-driven dust or sand might lodge or sand or mud be swept by the mimic flood caused by a thunder shower. So there are tracks in strata of every age. At first those of invertebrates after the worm burrows the curious complicated trails of animals believed to be akin to the king crab, broad-ribbed, ribbon-like paths ascribed to trilobites, then faint scratches of insects and the shallow-palmed prints of salamanders and the occasional slender sprawl of a lizard, then footprints big and little of the horde of dinosaurs and finally miles above the Cambrian marks of mammals. Sometimes, like the tracks of salamanders and reptiles in the carboniferous rocks of Pennsylvania and Kansas, these are all we have to tell of the existence of air-breathing animals. Again, as with the iguanodon, the foot to fit the track may be found in the same layer of rock, but this is not often the case. Although footprints in the rocks most often have been seen, they seem to have attracted little or no notice from scientific men until about 1830 to 1835, when they were almost simultaneously described both in Europe and America. Even then it was some time before they were generally conceded to be actually the tracks of animals, but like worm burrows and trails they were looked upon as the impressions of seaweeds. The now famous tracks in the brownstone of the Connecticut Valley seem to have first been seen by Pliny Moody in 1802 when he plowed up a specimen on his farm showing small imprints which later on were popularly called the tracks of Noah's Raven. Discovery passed without remark until in 1835 the footprints came under the observation of Dr. James Dean, who in turn called Professor Hitchcock's attention to them. The latter at once began a systematic study of these impressions, publishing his first account in 1836 and continuing his researches for many years in the course of which he brought together the fine collection in Amherst College. At that time dinosaurs were practically unknown and it is not to be wondered at that these three-toed tracks, great and small, were almost universally believed to be those of birds. So it is greatly to the credit of Dr. Dean who also studied these footprints that he was led to suspect that they might have been made by other animals. This suspicion was partly caused by the occasional association of four and five-toed prints with the three-toed impressions and partly by the rare occurrence of imprints showing the texture of the sole of the foot which was quite different from that of any known bird. In the light of our present knowledge we are able to read many things in these tracks that were formerly more or less obscure and to see in them a complete verification of Dr. Dean's suspicion that they were not made by birds. We see clearly that the long tracks called Animoepus with their accompanying short forefeet mark where some dinosaurs squatted down to rest or progressed slowly on all fours as does the kangaroo when feeding quietly. And we interpret the curious heart-shaped depression sometimes seen back of the feet, not as the mark of a stubby tail but as made by the ends of the slender pubes, bones that help form the hip joints. Then too the mark of the inner or short first toe is often very evident, although it was a long time before the bones of this toe were actually found and many of the dinosaurs now known to have four toes were supposed to have but three. Footnote It is to be noted that a leaping kangaroo touches the ground neither with his heel nor his tail but that between jumps he rests momentarily on his toes only. Hence impressions made by any creature that jumped like a kangaroo would be very short. End of footnote It seems strange and it is strange that while so many hundreds of tracks should have been found in the limited area exposed to view so few bones have been found our knowledge of the veritable animals that made the tracks being a blank. A few examples have it is true been found but these are only a tithe of those known to have existed. While of the great animals that strode along the shore leaving tracks fifteen inches long in a yard apart pressed deeply into the hard sand not a bone remains. The probability is that the strata containing their bones lie out to see whether their bodies were carried by tithes and currents and that we may never see more than the few fragments that were scattered along the seaside. That part of the valley of the Connecticut where in the footprints are found seems to have been a long narrow estuary running southward from Turner's Falls, Massachusetts where the tracks are most abundant and most clear. The topography was such that this estuary was subject to sudden and great fluctuations of the water level large tracks of shore being now left dry to bake in the sun and again covered by turbid water which deposited on the bottom a layer of mud. Over and over again this happened forming layer upon layer of what is now stone sometimes the lapse of time between the deposits being so short that the tracks of the big dinosaurs extend through several sheets of stone. While again there was a period of drought when the shore became so dry and firm as to retain but a single shallow impression. Something of the wealth of animal life that roamed about this estuary may be gathered from the number of different footprints recorded on the sands and these are so many and so varied that Professor Hitchcock in two extensive reports enumerated over one hundred fifty species representing various groups of animals. One little point must however be born in mind that mere size is no sure indication of differences in dealing with reptiles for these long-lived creatures grow almost continuously throughout life so that one animal even may have left his footprints over and over in assorted sizes from one end of the valley to the other. The slab shown in figure seven is a remarkably fine example of these Connecticut River footprints. It shows in relief forty-eight tracks of the animal called Brontazoam, Cillimanium, and six of a lesser species. It was quarried near Middletown in 1778 and for sixty years did duty as a flagstone fortunately with a face downwards. When taken up for repairs the tracks were discovered and later on the slab which measures three by five feet was transferred to the Museum of Amherst College. There is an interesting parallel between the history of footprints in England and America for they were noticed at about the same time, eighteen-thirty in both countries. In each case the tracks were in rocks of triassic age and in both instances the animals that made them have never been found. In England however the tracks first found were those ascribed to tortoises though a little later dinosaur footprints were discovered in the same locality. Oddly enough these numerous tracks all run one way from west to east as if the animals were migrating or were pursuing some well-known and customary route to their feeding grounds. For some reason triassic rocks are particularly rich in footprints. For from the strata of this same age in the Rhine Valley come those curious examples so like the mark of a stubby hand that Dr. Cowpe christened the beast supposed to have made them chyrotherium, beast with a hand suggesting that they had been made by some gigantic opossum. As the tracks measure five by eight inches it would have been rather a large specimen but the mammals had not then arisen and it is generally believed that the impressions were made by huge for their kind salamander-like creatures known as labyrinthodonts whose remains are found in the same strata. Footprints may aid greatly in determining the attitude assumed by extinct animals and in this way they have been of great service in furnishing proof that many of the dinosaurs walked erect. The impressions on the sands of the old Connecticut estuary may be said to show this very plainly but in England and Belgium is evidence still more conclusive in the shape of tracks ascribed to the iguanodon. These were made on soft soil into which the feet sank much more deeply than in the Connecticut sands and the casts made in the natural molds show the impression of toes very clearly. If the animals had walked flat footed as we do the prints of the toes would have been followed by a long heel mark but such is not the case. There are the sharply defined marks of the toes and nothing more showing plainly that the iguanodons walked like birds on the toes alone. More than this had these dinosaurs dragged their tails there would have been a continuous furrow between the footprints but nothing of this sort is to be found. On the contrary a fine series of tracks uncovered at Hastings England made by several individuals and running for seventy-five feet shows footprints only. Hence it may be fairly concluded that these great creatures carried their tails clear of the ground as shown in the picture of Thespisius the weight of the tail counterbalancing that of the body where crocodilians or some of the short-limb dinosaurs have crept along there is as we should expect a continuous furrow between the imprints of the feet. This is what footprints tell us when their message is read a right. When improperly translated they only add to the enormous bulk of our ignorance. Some years ago we were treated to accounts of wonderful footprints in the rock of the prison yard at Carson City, Nevada which according to the papers not only showed that men existed at a much earlier period than the scientific supposed but that they were men of great stature. This was clearly demonstrated by the footprints for they were such as might have been made by huge moccasin feet and this was all that was necessary for the conclusion that they were made by just such feet. For it is a curious fact that the majority of mankind seemed to prefer any explanation other than the most simple and natural particularly in the case of fossils and are always looking for a primitive race of gigantic men. Bones of the mastodon and mammoth have again and again been eagerly accepted as those of giants. A salamander was brought forward as evidence of the deluge, Homo diluvii testis, ammonites and their allies pose as fossil snakes and the petrified man flourishes perineally. However, in this case the prints were recognized by naturalists as having most probably been made by some great ground sloth such as the myladon or morotherium. These animals though belonging to a group whose headquarters were in Patagonia having extended their range as far north as Oregon. That the tracks seem to have been made by a biped rather than a quadruped was due to the fact that the prints of the hind feet fell upon and obliterated the marks of the fore. Still a little observation showed that here and there prints of the fore feet were to be seen and on one spot were indications of a struggle between two of the big beasts. The mud or rather the stone that had been mud bears the imprints of opposing feet one set deeper at the toes the other at the heels as if one animal had pushed and the other resisted. In the rock too are broad depressions bearing the marks of coarse hair where one creature had apparently sat on its haunches in order to use its forelimbs to the best advantage. Other footprints there are in this prison yard the great round spore of the mammoth the hoofs of a deer and the paws of a wolf indicating that here about there was some pool where all these creatures came to drink. More than this we learn that when these prints were made or shortly after a strong wind blew from the southeast for on that face of the ridges bounding the margin of each big footprint we find sand that lodged against the squeezed up mud and stuck there to serve as a perpetual record of the wind. References Almost every museum has some specimen of the Connecticut Valley footprints but the largest and finest collections are in the museums of Amherst College Massachusetts and Yale University although owing to lack of room only a few of the Yale specimens are on exhibition. The collection at Amherst comprises most of the types described by Professor E. Hitchcock in his Acknowledgy of New England a work in two fully illustrated quarto volumes. Other footprints are described and figured by Dr. J. Dean in Icnographs from the Sandstone of the Connecticut River. End of Chapter 3 Chapter 4 of Animals of the Past by Frederick Lucas This LibriVox recording is in the public domain. Recording by Jeffrey Smith Rulers of the Ancient Seas A time there was when the universe was darkness and water wherein certain animals of frightful and compound mean were generated. There were serpents and other creatures in the mixed shapes of one another. The Archaic Genesis History shows us how in the past nation after nation has arisen increased in size and strength extended its bounds and dominion until it became the ruling power of the world and then passed out of existence often so completely that nothing has remained but a few mounds of dirt marking the graves of former cities. And so it has been with the kingdoms of nature. Just as Greece, Carthage, and Rome were successively the rulers of the sea in the days that we call old, so long before the advent of man the seas were ruled by successive races of creatures whose bones now lie scattered over the lands of the ancient seas even as the wrecks of galleys lie strewn over the bed of the Mediterranean. For a time the armor-clad fishes held undisputed sway. Then their reign was ended by the coming of the sharks who in their turn gave way to the fish-lizards the ichthyosaurs and plesiosaurs. These, however, were rather local in their rule. But the next group of reptiles to appear on the scene the great marine reptiles called mosasaurs practically extended their empire around the world from New Zealand to North America. We properly call these reptiles great for so they were. But there are degrees of greatness and there is a universal tendency to think of the animals that have become extinct as much greater than those of the present day to magnify the reptile that we never saw as well as the fish that got away. And it may be safely said that the greatest of animals will shrink before a two-foot rule. As a matter of fact no animals are known to have existed that were larger than the whales. And while there are now no reptiles that can compare in bulk with the dinosaurs there were few mosasaurs that exceeded in size a first-class crocodile. An occasional mosasaur reaches a length of 40 feet but such are rare indeed and one even 25 feet long is a large specimen while the great mugger or man-eating crocodile grows if permitted to a length of 25 or even 30 feet and need not be ashamed to match his bulk and jaws against those of most mosasaurs. Footnote. It is surprising to find Professor Cope placing the length of the mosasaurs at 70, 80 or 100 feet as there is not the slightest basis for even the lowest of these figures. Professor Williston, the best authority on the subject states in his volume on the cretaceous reptiles of Kansas that there is not in existence any specimen of a mosasaur indicating a greater length than 45 feet. End of footnote. The first of these sea reptiles to be discovered has passed into history and now reposes in the Jardin de Plante, Paris after changing hands two or three times the original owner being dispossessed of his treasure by the subtleties of law while the next holder was deprived of the specimen by main force. Thus the story is told by M. Foge St. Fond as rendered into English in mantels, petrifactions and their teachings. Some workmen in blasting the rock in one of the caverns of the interior of the mountain perceived to their astonishment the jaws of a large animal attached to the roof of the chasm. The discovery was immediately made known to M. Hoffman who repaired to the spot and for weeks presided over his task of separating the mass of stone containing these remains from the surrounding rock. His labours were rewarded by the successful extrication of the specimen which he conveyed in triumph to his house. This extraordinary discovery, however, soon became the subject of general conversation and excited so much interest that the canon of the cathedral which stands on the mountain resolved to claim the fossil in right of being lord of the manner and succeeded after a long and harassing lawsuit in obtaining the precious relic. It remained for years in his possession and Hoffman died without regaining his treasure. At length the French Revolution broke out and the armies of the Republic advanced to the gates of Maastricht. The town was bombarded. But at the suggestion of the Committee of Savins who accompanied the French troops to select their share of the plunder, the artillery was not suffered to play on that part of the city in which the celebrated fossil was known to be preserved. In the meantime the canon of St. Peter's shrewdly suspecting the reason why such peculiar favour was shown to his residents removed the specimen and concealed it in a vault. But when the city was taken the French authorities compelled him to give up his ill-gotten prize which was immediately transmitted to the Jardin de Plante at Paris where it still forms one of the most interesting objects in that magnificent collection and there it remains to this day. The seas that rolled over western Kansas were the headquarters of the Mosasores and hundreds, I thousands of specimens have been taken from the chalked bluffs of that region. Some of them in such a fine state of preservation that we are not only well acquainted with their internal structure but with their outward appearance as well. They were essentially swimming lizards great overgrown and distant relatives of the monitors of Africa and Asia especially adapted to a roving predatory life by their powerful tails and paddle-shaped feet. Their cup-and-ball vertebrae indicate great flexibility of the body. Their sharp teeth denote ability to capture slippery prey and the structure of the lower jaw shows that they probably ate in a hurry and swallowed their food entire or bolted it in great chunks. The jaws of all reptiles are made up of a number of pieces but these are usually so spliced together that each half of the jaw is one inflexible or nearly inflexible mass of bone. In snakes which swallow their prey entire the difficulty of swallowing animals greater in diameter than themselves is surmounted by having the two halves of the lower jaw loosely joined at the free ends so that these may spread wide apart and thus increase the gape of the mouth. This is also helped by the manner in which the jaw is joined the head. The pelican solves the problem by the length of his mandibles this allowing so much spring that when open they bow apart to form a nice little landing net. In the mosasaurs as in the cormorants among birds there is a sort of joint in each half of the lower jaw which permits it to bow outward when opened and this aided by the articulation of the jaw with the cranium adds greatly to the swallowing capacity. Thus in nature the same end is attained by very different methods. To borrow a suggestion from Professor Cope if the reader will extend his arms at full length the palms touching and then bend his elbows outward he will get a very good idea of the action of a mosasaurs jaw. The western sea was a lively place in the day of the great mosasaurs for with them swam the king of turtles Arcalon as Mr. Wheeland has fitly named him a creature a dozen feet or more in length with a head a full yard long while in the shallows prowled great fishes with massive jaws and teeth like spikes. There too was the great toothed diver Hesperornis, see page 83 while over the waters flew pterodactyls with a spread of wing of twenty feet largest of all flying creatures and not improbably nay very probably fish eaters too and when each and all of these were seeking their dinners there were troubleous times for the small fry in that old cans and sea and then there came a change to the south to the west to the north the land was imperceptibly but surely rising perhaps only an inch or two in a century but still rising until the ocean in which flourished this abundant and vigorous life was at last completely enclosed on the west by elevations of sea bottom so that it only communicated with the Atlantic and Pacific at the Gulf of Mexico and the Arctic sea. The continued elevation of both eastern and western shores contracted its area and when ridges of the sea bottom reached the surface forming long low bars parts of the water area were included and connection with salt water prevented. Thus were the living beings imprisoned and subjected to many new risks to life. The stronger could more readily capture the weaker while the fishes would gradually perish through the constant freshening of the water. With the death of any considerable class the balance of food supply would be lost and many large species would disappear from the scene. The most omnivorous and enduring would longest resist the approach of starvation but would finally yield to inexorable fate the last one caught by the shifting bottom among shallow pools from which his exhausted energies could not extricate him. Footnote Cope the vertebrata of the Cretaceous formations of the west, page 50 being the report of the United States geological survey of the territories volume two. End of footnote Like the fossil man the sea serpent flourishes perennially in the newspapers and despite the fact that he is now mainly regarded as a joke there have been many attempts to habilitate this mythical monster and place him on a foundation of firm fact. The most earnest of these was that of William Udomans who expressed his belief in the existence of some rare and huge seal-like creature whose occasional appearance in southern waters gave rise to the best authenticated reports of the sea serpent. Among other possibilities it has been suggested that some animal believed to be extinct had really lived over to the present day. Now there are a few waifs spared from the wrecks of ancient faunas stranded on the shores of the present such as the Australian Ceratidus and the Garpikes of North America and these and all other creatures that could be mustered in were used as proofs to sustain this theory. If it was said these animals have been spared why not others? If a fish of such ancient lineage as the Garpike is so common as to be a nuisance why may there not be a few plesiosaurus or a mosasaur somewhere in the depths of the ocean? The argument was a good one the more that we may suppose almost anything but it must be said that no trace of any of these creatures has so far been found outside of the strata in which they have long been known to occur and all the probabilities are opposed to this theory. Still if some of these creatures had been spared they might well have passed for sea serpents even though Zougladon the one most like a serpent in form was the one most remotely related to snakes. Zougladon the yolk tooth so named from the shape of its great cutting teeth was indeed a strange animal and if we wonder at the Greenland Whale whose head is one third its total length we may equally wonder at Zougladon with four feet of head, ten feet of body and forty feet of tail. No one seeing the bones of the trunk and tail for the first time would suspect that they belong to the same animal for while the vertebrae of the body are of moderate size those of the tail are for the bulk of the creature the longest known measuring from fifteen to eighteen inches in length and weighing in a fossil condition fifty to sixty pounds. In life the animal was from fifty to seventy feet in length and not more than six or eight feet through the deepest part of the body while the tail was much less. The head was small and pointed the jaws well armed with grasping and cutting teeth and just back of the head was a pair of short paddles not unlike those of a fur seal. It is curious to speculate on the habits of a creature in which the tail so obviously wagged the dog and whose articulations all point to great freedom of movement up and down. This may mean that it was an active diver descending to great depths to prey upon squid as the sperm whale does today while it seems quite certain that it must have reared at least a third of its great length out of the water to take a comprehensive view of its surroundings and if size is any indication of power the great tail which obviously ended in flukes like those of a whale must have been capable of propelling the beast at a speed of twenty or thirty miles an hour. Something of the kind must have been needed in order that the small head might provide food enough for the great tail and it has been suggested that inability to do this was the reason why Zougladon became extinct. On the other hand it has been ingeniously argued that the huge tail served to store up fat when food was plenty which was drawn upon when food became scarce. The fur seals do something similar to this for the males come on shore in May rolling in blubber and depart in September lean and hungry after a three months fast. Zougladons must have been very numerous in the old Gulf of Mexico for bones are found abundantly through portions of our southern states. It was also an inhabitant of the old seas of southern Europe but as we shall see it gave place to the great fossil shark and this in turn passed out of existence. Still common though its bones may be stories of their use for making stone walls and these stories are still in circulation resolve themselves on close scrutiny into the occasional use of a big vertebra to support the corner of a corn crib. The scientific name of Zougladon is Bacillosaurus setoides the whale like King Lizard. The first of these names Bacillosaurus having been given to it by the original describer Dr. Harlan who supposed the animal to have been a reptile. Now it is a primary rule of nomenclature that the first name given to an animal must stick and may not be changed even by the act of a zoological congress. So Zougladon must so far as its name is concerned masquerade as a reptile for the rest of its paleontological life. This however really matters very little because scientific names are simply verbal handles by which we may grasp animals to describe them and Dr. Lecont to show how little there may be in a name called a beetle Giascatus. Owen's name of Zougladon although not tenable as a scientific name is too good to be wasted and being readily remembered and easily pronounced may be used as a popular name. One might think that a creature 60 or 70 feet long was amply long enough but Dr. Albert Koch thought otherwise and did with Zougladon as later on he did with the mastodon combining the vertebrae of several individuals until he had a monster 114 feet long. This he exhibited in Europe under the name of Hydrarchus or Water King finally disposing of the composite creature to the museum of Dresden where it was promptly reduced to its proper dimensions. The natural makeup of Zougladon is sufficiently composite without any aid from man for the head and paddles or not unlike those of a seal the ribs are like those of a manatee and the shoulder blades are precisely like those of a whale while the vertebrae are different from those of any other animal even its own cousin and lesser contemporary Dorodon. There were also tiny hind legs tucked away beneath skin but these as well as many other parts of the animal structure were unknown until Mr. Charles Schuchert collected a series of specimens for the National Museum from which it was possible to restore the entire skeleton. Owing to a rather curious circumstance the first attempt at a restoration was at fault. Among the bones originally obtained by Mr. Schuchert there were none from the last half of the tail an old gully having cut off the hinder portion of the backbone and destroyed the vertebrae. Not far away however was a big lump of stone containing several vertebrae of just the right size and these were used as models to complete the paper mache skeleton shown at Atlanta in 1894. But a year after Mr. Schuchert collected a series of vertebrae beginning with the tip of the tail and these showed conclusively that the first lot of tail vertebrae belonged to a creature still undescribed and one probably more like a whale than Zougladon himself whose exact relationships are a little uncertain as may be imagined from what was said of its structure. Mixed with the bones of Zougladon was the shell of a turtle nearly three feet long and part of the backbone of a great water snake that must have been 25 feet long, both previously quite unknown. One more curious thing about Zougladon bones remains to be told and then we are done with him. Ordinarily a fossil bone will break indifferently in any direction but the bones of Zougladon are built like an onion of concentric layers and these have a great tendency to peel off during the preparation of a specimen. And now as the wheels of time and change rolled slowly on sharks again came uppermost and the warmer Eocene and Myocene oceans appear to have fairly teamed with these sea wolves. There were small sharks with slender teeth for catching little fishes. There were larger sharks with saw-like teeth for cutting slices out of larger fishes and there were sharks that might almost have swallowed the biggest fish of today whole. Sharks of a size the waters had never before contained and fortunately do not contain now. We know these monsters mostly by their teeth for their skeletons were cartilaginous and this absence of their remains is probably the reason why these creatures are passed by while the adjectives huge, immense, enormous are lavished on the mosasaurus and plesiosaurus animals that the great toothed shark carcaradon megalodon might well have eaten at a meal. For the gaping jaws of one of these sharks with its hundreds of gleaming teeth must at a moderate estimate have measured not less than six feet across. The great white shark, the man-eater so often found in story books so rarely met with in real life attains a length of 30 feet and a man just makes him a good satisfactory lunch. Now a tooth of this shark is an inch and a quarter long while a tooth of the huge megalodon is commonly three, often four and not infrequently five inches long. Applying the rule of three to such a tooth as this would give a shark 120 feet long bigger than most whales to whom a man would be but a mouthful just enough to whet his shark ship's appetite. Even granting that the rule of three unduly magnifies the dimensions of the brute and making an ample reduction there would still remain a fish between 75 and 100 feet long quite large enough to satisfy the most ambitious of tuna fishers and to have made bathing in the myocene ocean unpopular. Contemporary with the great toothed shark was another and closely related species originated with him in eocene times and these two may possibly have had something to do with the extinction of zoogledon. This species is distinguished by having on either side of the base of the great triangular cutting teeth a little projection or cusp like the ear on a jar so that this species has been named or irred. The edges of the teeth are also more saw-like than in those of its greater relative and as the species must have attained a length of 50 or 60 feet it may with its better armature have been quite as formidable and as perhaps the readers of these pages may know the supply of teeth never ran short. Back of each tooth, one behind another arranged in serried ranks lay a reserve of six or seven smaller but growing teeth and whenever a tooth of the front row was lost the tooth immediately behind it took its place and like a well-trained soldier kept the front line unbroken. Thus the teeth of sharks are continually developing at the back and all the teeth are steadily pushing forward a very simple mechanical arrangement causing the teeth to lie flat until they reach the front of the jaw and come into use. Once fairly started in life these huge sharks spread themselves throughout the warm seas of the world for there was none might stand before them and say nay. They swarmed along our southern coast from Maryland to Texas. They swarmed everywhere that the water was sufficiently warm for their teeth occur in tertiary strata in many parts of the world and the deep-sea dredges of the challenger and albatross have brought up their teeth by scores and then they perished, perished as utterly as did the host of Sennacherib. Why? Did they devour everything large enough to be eaten throughout their habitat and then fall to eating one another? Again we do not know. But perished they did while the smaller white shark which came into being at the same time still lives as if to emphasize the fact that it is best not to overdo things and that in the long run the victory is not always to the largest. References. The finest Mosasaurus skeleton ever discovered an almost complete skeleton of Tylosaurus dyspilore twenty-nine feet in length may be seen at the head of the staircase leading to the Hall of Paleontology in the American Museum of Natural History, New York. Another good specimen may be seen in the Yale University Museum which probably has the largest collection of Mosasaurus in existence. Another fine collection is in the Museum of the State University of Kansas at Lawrence. The best zougladon, the first to show the vestigial hind legs and to make clear other portions of the structure is in the United States National Museum. The great sharks are known to be found in the country by their teeth only and as these are common in the phosphate beds specimens may be seen in almost any collection. In the United States National Museum the jaws of a twelve foot blue shark are shown for comparison. The largest tooth in that collection is five and three fourths inches high and five inches across the base. There are six five teeth of the blue shark to fill the same number of inches. The Mosasaurus are described in detail by Professor S.W. Williston in volume four of the University Geological Survey of Kansas. There is a technical and consequently uninteresting account of zougladon in volume 23