Extinct Animals

Frontispiece

Preface

This book is a corrected shorthand record of the lectures I gave to a young audience at the Royal Institution in London over the Christmas holidays of 1903-4. The lantern slides I showed have been turned into printing blocks. Many of them were photographs made specially for the lectures under my direction, from specimens in the Natural History Museum, because I wanted, wherever I could, to show what I was talking about with pictures of the real thing. Some of them have come out reasonably well in print. For several of the slides and figures I owe thanks to my friend and colleague Dr. Arthur Smith Woodward, Keeper of the Geological Department of the Museum, who helped me in many ways with these lectures. Other friends lent me slides and the blocks made from them: Mr. R. Lydekker, Dr. Bather, Dr. Andrews and Mr. Pyecraft of the Natural History Museum, and Professor Sollas of Oxford. I'm grateful as well to the Trustees of the British Museum for letting me use several figures of extinct animals from the guidebooks to the Natural History Museum published by their order, and to Messrs. Macmillan & Co. and Mr. John Murray.

I hope nobody will take this little book for anything grander than what it is: an attempt to get young people interested in a wonderfully absorbing subject. It doesn't pretend to give more than a peep at the strange and marvellous history of extinct animals.

	E. RAY LANKESTER.
	1905.

Chapter One: Animals Which Have Lately Become Extinct—The Strata of the Earth’s Crust

Extinct animals are animals that no longer exist alive. Of course, enormous numbers of individual animals, and of people too, are extinguished, or made extinct, every year, every month and every day.

But the extinct animals I want to talk about in these lectures are extinct kinds of animals: kinds that once flourished and held their own, and are now nowhere alive on the face of the globe.

Some of them we know by tradition. People of past ages saw certain animals that are now extinct, wrote about them and even drew them, and their records have been carefully handed down to us. Others we know because we find their bones buried in the ground, some quite near the surface and others deep in the rocks, far down in the earth, where they can be dug out. Our first illustration (Fig. 1) is a photograph of a sample of such buried bones. Many of these bones have been so big, so huge, that they gave rise to the idea that giants lived in former days. It apparently never occurred to the people who found them that they were the bones of extinct animals and not of some great race of men.

Anything buried that shows us a world which has passed away excites tremendous interest when it is dug up, whether it is the great buried town of Pompeii or one of the buried cities of Egypt. Using whatever records survive, we try to work out what each object found there meant, and what sort of people owned it and how they lived. The remains of extinct animals that we dig up hold the same kind of interest, except that many of them are far older than any human remains ever found. We call the ruins of an ancient Egyptian city some thousands of years old. But many of the animals I'll be telling you about in these lectures have to be dated not in thousands of years but in millions, in fact in so many years that no number we're used to will bring the facts home to my readers.

Far down in the depths of the earth we find the bones and teeth of such animals, well preserved. From them we can tell what kind of animals they were, where they lived, what they ate, how they moved, and in fact what they looked like altogether.

Some educationists argue (I don't agree with them) that knowledge should be put before young people in logical order. Before you talk to the young or the uninstructed about extinct animals, they say, you must give them a complete course on living animals: beginners must first learn how living animals are built, and must study the geography and history of the earth's crust in which extinct animals are found, and only then can they look at extinct animals with any intelligence. That opinion exists. But I don't believe in that method. In my judgment the logical method of teaching or studying is a mistaken one. The whole art of education consists in exciting the desire to know. Show someone something wonderful, mysterious, astonishing and marvellous, dug out of the earth beneath our feet, and you may wake up the desire to understand it and learn more about it. The strangeness of the bones and teeth of extinct animals will lead a boy or girl on to learning about the bones and teeth of living animals, so as to compare them, and so on to learning more about the strange remains that have been dug up. I believe that's what usually happens. It certainly happened to me. When I was very young, as young as any of my readers or younger, a very kind lady, my governess, used to take me to the Natural History Museum of those days. It was then in a remote part of London called Bloomsbury; it has since moved to Cromwell Road, Kensington. As a child I was absolutely fascinated by the remains of strange extinct animals I saw there. I hope the boys and girls who read these pages will share some of that interest and fascination, and will go on from these lectures to see the actual specimens on show at the Natural History Museum. Really, these lectures are little more than an invitation to all of you to go and see the real things at Cromwell Road, of which this book can only show you photographs.

Now I'll show you the portrait of a creature that has always fascinated me with its stony stare. It is the head of an Ichthyosaurus, dug out of the rock at Lyme Regis in the south of England many years ago (Fig. 2). The eye is unusually well preserved. A circle of bony plates, like those found in the eyes of birds, gives it an expression of interest that few fossils can boast. It was dug out of the rocks by a wonderful lady, Miss Anning, who at the beginning of the last century collected a great many such remains from the cliffs on the seashore. For many years the front part of this specimen was missing, but in the end it too was found and dug out of the rocks. I'll have more to say later about creatures of this kind.

Another creature that fascinated me is shown here as it stands in the East Court of the Museum (Fig. 3). In its build and nature it is like a sloth. But instead of living in a tree, it stood on the ground and pulled the tree down to itself to feed on the young branches. The skeletons of a great many of these huge sloths have been found in the gravels of South America.

This skeleton (Fig. 4) shows us another strange great creature, like a huge guinea pig with tremendous chisel-like teeth in front. It too is found in South America. This is the Toxodon.

The next picture (Fig. 5) shows the skulls of two rhinoceroses. The lower one belongs to a living African beast known as the square-mouthed or white rhinoceros. He is called white, apparently, not because he is black, but in spite of the fact that he is black. As a matter of fact, he sometimes has a few white patches. But it's enough to know him as the square-mouthed rhinoceros.

The upper specimen is the skull and lower jaw of a rhinoceros dug up last year in the City of London, at Whitefriars, under the offices of the well-known newspaper the Daily Chronicle. Digging in the mud and clay there, the workmen came upon this rhinoceros skull. Many like it have been found in English river gravels, and so we know that such animals lived on the banks of the Thames many thousands of years ago. That specimen too is in the Natural History Museum.

Here (Fig. 6) is a thigh bone; you can see how enormous it is from the full-grown man standing beside it. It belonged to a huge kind of reptile, bigger than an ordinary elephant, bigger even than the biggest African elephant, without counting the reptile's tail. Remains like this have been found in England, but the largest have been found in the United States.

These are just a few samples of the remains of extinct animals, to give you an idea of the creatures I want to tell you about. Naturally I can't mention in these pages all the many thousands of kinds of extinct animal that are known. I can only hope to show you pictures of a few samples, and I hope they will be enough to send you looking further into the matter: to look at the real specimens and read bigger books, until you come to feel the same interest and pleasure in examining them that I do.

The world we live on has been changing, always, for millions of years. Nothing today is as it was even a hundred years ago. A thousand years brings enormous changes, a completely different state of things in fact. There are cities now where forests grew. Animals that lived a thousand years ago have vanished altogether. And this history of change hasn't been going on for a mere thousand years, but for hundreds and thousands and millions of years. The changes have been incessant, and very great.

The difficulty in studying extinct animals, and the geology that goes with them, is to think of long enough stretches of time. If you look at that clock you can't see the hand moving, and yet it is moving. In the same way, in a whole human lifetime you'll hardly notice any difference in the rivers, the seashore and the cliffs. But take a long enough span, say a thousand years or several thousand, and compare how things were a thousand years ago with how they are today, and you'll see great changes. The difficulty is to grasp this change, because it comes too slowly for our short lives to give us any real, definite experience of it, just as we fail to see the hands of the clock move when we glance at them for a second. I want you to keep that in mind all through these lectures.

We know of animals that are becoming extinct even now. In this country we have historical records of animals that have become extinct, and I'll show you one that used to live here.

This creature, the grey wolf (Fig. 7), lived in England until the time of Henry VIII, at the end of the fifteenth century, and in Scotland and Ireland for 150 years after that. But people wiped it out entirely because of its ravenous and dangerous habits. Though it is extinct in England, it still lives in France, Spain, Germany and Russia.

Here is another animal (Fig. 8), the beaver, which used to live in England and was found in Wales as late as the sixteenth century. It still lives in France, on the banks of the streams at the mouth of the Rhone, and in Russia and Scandinavia. In America, in Canada, beavers are still more plentiful.

Another creature that records tell us lived all over Europe, and has ceased to exist, is the great bull or Urus of Julius Caesar (Fig. 9). Caesar mentions it as living wild in various parts of Europe and says it was nearly as big as an elephant. Well, no such great wild ox exists in Europe now. The last one was killed near Warsaw in 1627. All we have now are the breeds descended partly from it and partly from other kinds of cattle, and they look quite different. Some people believe that the more or less wild cattle in parts of England, for instance the herds on Lord Tankerville's and the Duke of Hamilton's estates, are survivors of this race of wild oxen. But that is probably a mistake. They are really descended from cattle the Romans brought over, which ran wild. They are not the Urus of Julius Caesar, which was a good deal bigger than the largest domesticated cattle, bigger even than the white oxen of Umbria.¹

This one (Fig. 10) is another animal that has become extinct. It isn't a zebra, though I expect some of you thought it must be. This is the quagga, which differs from the zebra in being striped only at the front. The quagga lived in South Africa and was quite common there until forty years ago. This photograph was taken of one that lived in the Zoological Gardens some twenty-five years ago, and its stuffed skin is kept in the Natural History Museum. The quagga has now entirely ceased to exist, because the country it roamed over has been taken up and farmed by white settlers. There are no living quaggas left anywhere. This animal has been wiped out in our own lifetime. Zebras (Fig. 11), on the other hand, are still common enough in Africa, with their beautiful stripes on the head, and on the hindquarters and legs as well as the front.

Here is an animal that people fear is on its way to extinction: the giraffe (Fig. 12). In South Africa it is extinct already. Sportsmen now go after it in equatorial Africa, where it still lives in great numbers, and we hope the Government will now protect it properly. Two new, well-mounted specimens have recently been put on show in the Natural History Museum. The giraffe's neck is often drawn rising from the body in a graceful curve, like a swan's. But the neck's true position is the one you see here (Fig. 12), and the specimens in the Natural History Museum show it correctly.

This is a picture (Fig. 13) of a curious creature known as the sea-cow, found in the Aleutian Islands, between North America and Asia. It was discovered in the eighteenth century by the travelling naturalist Steller. No sooner was it found than sailors went to its islands, knocked it on the head and ate it, and in about ten years it had ceased to exist. This picture is from Steller's own drawing. It was an enormous creature, some twenty feet long and shaped something like a seal. But it was really neither a seal nor a whale. It belonged to a peculiar group of plant-eating sea mammals, the Sirenians, and it had a small head, flipper-like front limbs, no hind limbs at all, and a tail like a fish's.

Fig. 14 shows the skull of the same animal. It had no teeth; it had bony plates instead.

This is the picture of a famous animal (Fig. 15), for you must understand that birds are animals. You'll have been handed a list of the groups of animals (see the end of this chapter). I won't have room to explain it at any length, but it gives the division of animals into groups and how they are related to one another. It shows how they are classified, so I needn't come back to the classification again.

This picture (Fig. 15) is the portrait of an interesting bird, the great auk. It is only about 2½ feet tall. It looks like a penguin, but it is really related to the puffin and the albatross. Fig. 15a shows its egg, which every so often we read in the newspapers has been sold to some enthusiastic egg collector for as much as £300. Nearly a hundred eggs of this bird are known, because it only became completely extinct some sixty years ago. It used to be found on the rocky islands off the north of Scotland, Shetland, Iceland and Greenland. But it has now ceased to exist entirely. It is very hard to say why it died out, because it had not been hunted down. Since it became extinct we have been able to learn about it by finding its skeleton buried in sand and guano at certain places on the coast of Newfoundland.

Here (Fig. 16) is another creature, the dodo, a bird which, like Steller's sea-cow, became extinct almost as soon as it became known. The early explorers found it on the island of Mauritius, the Portuguese first and then the Dutch. The bird couldn't fly; it was too fat for its little wings to lift it off the ground. The sailors knocked it on the head and the pigs they brought with them harried it, and it was soon wiped out. Around the beginning of the seventeenth century, between 1610 and 1620, live dodos were brought to Europe and exhibited as a show. At Oxford we once had a stuffed one, acquired by that ingenious and worthy gentleman Mr. Elias Ashmole, who gave his collections to the University 250 years ago. But it went mouldy and the insects got into it, and a hundred years ago the Vice-Chancellor and Proctors of the University of Oxford ordered the dodo to be destroyed. They do not like mouldy things at Oxford. The curator, though, cut off the head and one foot and kept them. That head and foot, with another foot in London and a skull in Copenhagen, are about all that is left of the dodos Europeans saw alive. But since the dodo became extinct, skeletons and bones of it have been found by digging in the mud of a lake in Mauritius (Fig. 17).

This (Fig. 18) is another interesting creature, whose kind is on the road to extinction. It is probably the oldest living land animal. It was brought from the Seychelles, where its kind is fast dying out. Tortoises of great size have been found on various ocean islands. This one was brought to Mauritius in 1764 and is still alive there. That means it has been in captivity for 140 years, in the Court House garden on Mauritius, and how old it was when it arrived there nobody can say.

A question of great interest is: "What makes animals become extinct?" In many cases it is obvious that another animal, Man, interferes. He kills and eats them, or takes their food, or occupies their ground, or cuts down the forests they live in, and so on. But before man appeared on the scene there were changes going on all the same, and different kinds of animals followed one another. We know this because we find the remains of different animals at different depths in the earth's crust, in the different strata, or layers, that have been laid down one after another. The cause of these changes, the cause of the extinction of animals, is a very complicated and difficult question, and I don't intend to go into it at any length. It is bound up, of course, with the whole doctrine of the origin of the different kinds of animals. We all recognize now that the different forms of animals have developed gradually, by natural birth, from ancestral forms more or less like themselves. But the further back we go from the present day along the line of descent, the less like the present form the ancestors become. The original parent forms have given rise to very different branches of descendants. The descendants of a single ancestral form have branched out in different directions, just as some person named Smith in the time of the Conqueror has given rise to all sorts of Smiths. Some of them, perhaps, still actually work metal; others have become Ministers of State and Right Honourable judges; others own great estates; but every one of them can be traced back to the one original Smith. In the same way, many living animals of all sorts of appearance and shape can be traced back to one ancient ancestral form, and those ancestors again to still more primitive ones.

The reason the ancestral forms died out has really to do with the general change in the surface of the earth. New forms have gradually taken the place of old ones, because no piece of land stays the same for long. A thousand years, as I've said, is a mere nothing in this business, yet even in a thousand years there are great changes in the surface of the land. Land may rise far above the sea, and what was an island may become part of a continent. And part of a continent may partly sink and become an island; that is, the neck of land joining it to the continent may go under water. Then the conditions of life for the animals change a great deal. Currents such as the Gulf Stream are affected by these shifts of land and water. If certain changes took place, the warm water of the Gulf Stream would no longer warm certain lands; the climate would turn colder than the animals were used to. The animals that couldn't stand the cold would die out, while those that could would flourish.² All I would say is that changes in the arrangement of land and water have been a great cause in changing the forms of animals, and in bringing about the extinction of one set and the flourishing of another. Now I'll try to give you evidence that the surface of the land really does rise and sink like this.

Here (Fig. 19) is a photograph of the Temple at Pozzuoli, near Naples, on the shore of the Bay of Naples. It has been famous for something like eighty years, ever since Mr. Babbage examined and described it carefully and so brought geologists to visit it in crowds. Like most geologists, I have had the pleasure of seeing it myself. The three standing columns are discoloured up to a certain height. The lower part, as the diagram shows (Fig. 20), is riddled with little holes, burrowed by tiny sea creatures, and in the holes are small shells. The band is so sharply marked that it is certain the columns once stood in sea water up to that line. The evidence is quite complete. These columns were part of a temple or public palace in the great Roman town of Puteoli, which had a Roman road running in front of it along the seashore, between the temple and the sea. In Roman times the temple stood complete, in very much the same position relative to sea level as it does today, only rather higher up. Mr. Günther, of Oxford, searching the shoreline carefully, has found the remains of the Roman road under the sea, and the remains of the great blocks that ships tied up to when they brought their goods to Puteoli. I've made a drawing here of the town and its great public palace as they must have looked in Roman times (Fig. 21). In the distance is the island of Nisida; in the foreground are the palace and the town, the quay and the harbour. That is how things stood under the Roman Empire, in the third century of our era. Then came earthquakes; the columns were broken, and the city sank beneath the sea. We have no written history of this town. But we know that in the Middle Ages, in the eighth or ninth century, this whole stretch of the Italian coast had sunk many feet, and the columns stood broken in the sea. This is how Puteoli looked then (Fig. 22). The coast had sunk; the remains of the road were under the sea, and so were the columns, up to the height marked a on the diagram (Fig. 20). The whole land must have sunk as much as forty feet, since the temple or palace originally stood on high ground. It was then, while they stood under water in the ninth century, that the columns were bored into by the shellfish. Some more centuries have passed since, and the ground has risen again, to the state shown in the photograph (Fig. 23), a general view of the same stretch of coast that I drew from imagination in Figs. 21 and 22. The land rose out of the water again. But the sea left its mark on the columns, showing exactly how deep they had been sunk in the centuries between.

This is reckoned one of the clearest and most direct proofs that the level of the ground changes. The change needn't be continuous or fast. It took some two or three centuries for that temple to sink into the water, and a few more centuries for it to come out again.

Movement of this kind is always going on. It isn't very obvious on our own coast, though you can see something of it on the Devonshire coast at Plymouth. The evidence for it is what are called raised beaches, above the level of the sea. In Norway this kind of thing is very obvious. In South America it is going on, and has gone on at an enormous rate for the last thousand years. Probably a great part of the height of the Andes has been gained within the last few thousand years by rapid uplift. When the first sailors landed on the coast of Chile, in the sixteenth century or thereabouts, they are said to have chiselled an inscription on the rocks at one spot. Here is an imaginary sketch of them doing it (Fig. 24). It is said, though I can't find any accurate record of it, that such inscriptions have now been found, lifted high up the cliff (see Fig. 25). We do know that many kinds of seashells are found 200 and 300 feet up the cliffs in that part of the world. According to the observations that have been made, the inscription we see the sailors cutting in Fig. 24 would after 300 years be found high and dry, some 150 feet up the cliff face. There's good reason to believe that the coast of South America is moving upward at the rate of half a foot to a foot a year. If it kept rising like that for a thousand years, the original shoreline would end up 500 feet above sea level.

What, then, is the general result of movement like this? I'll show you what would happen if the shores of England, the whole of this part of the world, were raised 600 feet. You'll see from this map (Fig. 26) that if the floor of the ocean were lifted 600 feet, the cross-shaded area would become dry land, and we should be joined by land to the neighbouring continent and islands. If the land were raised 3,000 feet, there would be still more dry land. Even the smaller change would make England part of the Continent of Europe.

By studying the extinct animals found in the various strata of the earth we can form an idea of how land and water were arranged in past times. Here is an arrangement of land and water that we can conclude must have existed in Europe in what is called the Middle Tertiary period (Fig. 27). All the darker part is sea and the pale part land; the arrangement is quite different, in fact, from today's. The whole surface of the earth has been shifting and changing all through time. Over the millions and millions of years of past ages, different seas have come into being, different continents, different dry land and different animals, all altered by the various influences of land and climate. And all this movement is brought about by the slow cracking and "curling" of the earth's crust, by the constant washing of the land's surface by rain and rivers, and by the waves of the sea eating away at the edge of the land. This "eating away" of the land by the sea, quite apart from any sinking of the land, has caused and is still causing every year great losses of land on the east coast of England, especially in Suffolk, where the great town of Dunwich has been swallowed by the sea. Elsewhere the sea throws up sand and adds miles of new land to the coast. The vast amount of material carried off the surface by rain and rivers is hard to imagine at first. Take the river Thames at Kingston. It has been found that something like 500,000 tons of solid salts of lime are carried past that spot every year, dissolved in the water. Now, a cube of limestone measuring a yard each way weighs about two tons. That means 250 thousand solid cubic yards of rock are carried past Kingston every year by this little river: enough to build a new St. Paul's Cathedral every year! Think, then, of the enormous quantities of solid matter dissolved and carried away by rivers like the Mississippi and the Amazon. And remember that besides this dissolved limestone, most rivers carry along almost as great a bulk of fine sand and mud! What becomes of it? It is laid down in layers and forms what we call stratified rock. You can see some of it on the seashore when the tide goes out, as layers of sand, but most of it settles far out on the deep bottom of the sea, where shell-making plants and animals take the lime out of the water. But where the land is rising, the sand or ground that is bared when the tide goes out will in a few years have been lifted clear of the sea and become hard rock. Layer is laid on layer and lifted from the sea bottom. Without going into detail, we can accept it as a fact that this building of layers, from material brought down off the land by rivers and washed from the coastline by the waves, produces what are called "stratified deposits." Now I'll show you some pictures of this stratification. Here (Fig. 28) are shells embedded in the Bognor rocks, laid down some thousand million years ago; there are many sorts of shells in them, whelk-like shells and volutes.

Whole skeletons of animals are sometimes found in the stratified deposits. This one (Fig. 29) comes from the stratified rock that forms the hills around Paris, the limy rocks of Montmartre.

Next let's see what fine mud can do in preserving the print of delicate structures such as insects' wings. Here are the wings of a dragonfly (Fig. 30), preserved in very ancient stratified rock, the Carboniferous. Here (Fig. 31) are the wings of a Pterodactyle, preserved in fine sandy limestone of Oolitic age. And here (Fig. 32) is a jellyfish; you can see its seal stamped, as it were, on the sand. It is many millions of years old, from the Oolitic rock.

Now let's look at the layering, or stratification, of rocks. This picture (Fig. 33) shows part of the cliff at Lyme Regis, where the Ichthyosaurus head I showed you just now was found. You can see layers of harder and softer material lying one on top of another. The next figure (Fig. 34) shows how the layers of the earth's surface can be bent. Without digging far into the earth you can reach a deep layer, or "stratum," brought near the surface by the general tilting.

This (Fig. 34) is part of the chalk cliff at Seaford, showing the strata tilted so that the deeper layers come to the surface.

Here (Fig. 35) is part of the shore at Lyme Regis, showing strata laid bare by the action of the sea. You can see a long series of layers lying one on top of another. They are slightly tilted, so that the deeper strata come to the surface near the person looking at them.

The tilting of the strata of the earth's crust is the rule and not the exception. Strata seldom lie strictly level. The crust of the earth is constantly being pushed slowly up or down, and "crumpled," as it were, or thrown into wavelike folds. The cause of this crumpling lies in the shrinking of the earth and in the movements of underground steam, which cause earthquakes and other earth movements. The "crust" of the earth is a mere skin. If we bored twenty miles into it we'd come to immensely hot molten material, and the crust is supported on this. You can't really say it "rests" on the deeper matter, because it is always shifting and crumpling, though very, very slowly. Consequently, depending on the height and depth of the folds in the crust, deeper strata, even very deep ones, can be brought to the surface, and as the raised folds are worn away by sea and rain and rivers, the deepest layers of all may be laid bare. That is how we are able to examine the oldest rocks and search them for the remains of the immensely ancient creatures they contain. The diagram (Fig. 36) will help to make clear how the pushing and crushing of the earth's crust into wavelike folds, like the ones you see when a tablecloth or carpet isn't spread flat, brings the deep strata to the surface, so that we can walk along a cutting or a cliff and come to deeper and older rocks as we go.

Here (Fig. 37) is a specimen that still shows ripple marks, just like the ones we see on the shore at low tide today. Raindrop marks are often preserved too on slabs of rock like this, which were once soft wet sand. On such surfaces we often find footprints, of birds and of reptiles. In some cases we don't know the animal itself (Fig. 38), only its footprints in the ancient rocks, which are now far from the sea and buried under thousands of feet of later rock. Here (Fig. 39) are the footprints of a great creature from the Isle of Wight that has left its print in the sandstone.

In Fig. 40 we've drawn a slab of Triassic rock with the five-fingered, hand-like footprints of the Cheirotherium (as it was once called), a huge salamander-like animal.

Tabular List of the Great Groups or Branches of the Pedigree of Animals

N.B. The list leaves out the less important great groups, and is purposely made simpler than the tables of classification in scientific textbooks.

Tabular List of the Chief Orders of the Vertebrate Classes: Mammals

N.B. The list is not complete.

Tabular List of the Chief Orders of the Vertebrate Classes: Reptiles

N.B. This does not claim to be a complete list.

Chapter Two: Strata and Land Surfaces—Teeth and Bones—Extinct Men—Flint Implements—The Mammoth Elephants and Mastodon—Classification of Animals

Before I tell you more about extinct animals, I want to make the point that what I have to say is true, and not mere imagination.

Some people talk about the "fairy tales of science." There never was a more unsuitable phrase. It is altogether wrong to speak as if fairy tales had anything to do with science. The wonderful things science shows us are as far from fairy tales as can be, because with the tales of science you can test what you are told: you can see the things I speak of, and you can find out for yourself whether what is said is true. That is the great pleasure of this study. You know that the things you examine, however astounding and incredible they seem, really exist, and are not mere imagination or fancy.

Now I want to turn to these large diagrams (Figs. 41 and 42). Fig. 41 deserves careful study. It sets out what has been discovered about the order in which deposits succeed one another, the stratified deposits I talked about in my last lecture. Down the left-hand side is the thickness of each deposit, as far as it has been worked out.

Most of the extinct animals, and all the great extinct animals I have to talk about, come in the upper part. Beneath them lies an enormous thickness of stratified rock that holds only sea creatures: fishes, a few crustaceans and things of that kind. But all the more interesting great animals left their bones in the higher strata. The topmost layer (the Recent and Pleistocene) is only some 200 feet thick, yet it stands for a period of something like 500,000 years. That being so, you can judge from the thickness of the deposits underneath what an immense stretch of time they represent. Before we reach the chalk we have gone down nearly 3,000 feet. The chalk itself is another 2,500 feet thick.

Even this reckoning probably falls short of the time that has passed. Allowing a thousand years for each foot gives only a rough measure of the time represented, because far more time has gone by than the lasting deposits, the strata, actually record. Strata have been broken up by the sea and by running water and laid down again, over and over; and it is likely that a good deal more than a thousand years has passed for each foot of the deposits that make up the stratified crust of the earth.

One important general fact, which I can't dwell on further, is that while it is true that the great animals come in the later stages of the world's history, there is a gradual succession from simpler to more complex forms of life. We find fishes at the top of the Silurian, great amphibians in the Carboniferous, the first reptiles in the Permian, then birds and crocodiles in the Triassic, and the first hairy warm-blooded four-footed animals in the Jurassic. The different kinds of animals follow one another in order of increasing complexity of structure, so that the highest animals are the last to appear.

This map of the world (Fig. 42) is of special interest, because it shows where different kinds of animals live now. It is meant to show something of the history of the migrations, the movements across the face of the earth, of the large animals that have lived on it. The line that cuts New Zealand off from the rest of the world, which we call Theriogaea, "the land of big animals," shows that the large islands of New Zealand have no such animals. Until man went there, some thousand years ago, there were no large animals; the largest animals were great birds. There were no cattle, no cats or dogs, not even mice. This piece of land thus seems to stand apart from the history of animal movements in the rest of the world. It is an old, detached land surface. Then you'll see a second line, between Australia and the rest of the world.

Australia is set apart by its marsupials (kangaroos, wombats, phalangers and so on). Young marsupials are very small when they are born, and their mother puts them into a pouch of skin over her teats. Animals that are nourished inside the mother before birth are much larger when they are born. They are the Placentals, and Australia has no native Placentals.

The greater part of the world (what's left when Australia is cut off) can be divided into the great Holarctic region, the northern band that takes in North America, Europe and northern Asia, with three other regions jutting down from it: South America, or the Neotropical region; the great African, or Ethiopian, region; and the Oriental, or Indian, region. The animals whose fossil remains we find in the Holarctic region migrated at different times in the world's history into these southern projections, which later took on their present shape.

The Neotropical region of South America was at one time a separate mass of land, and very peculiar animals lived on it, such as the great sloths and the armadillos, and strange birds.

In the Holarctic region we find, either still alive or buried in recent strata, the great hairy mammals: elephants and cattle, antelopes, deer, camels, horses, rhinoceroses, tapirs, pigs, hippopotamuses, tigers and lions, and such creatures. Dig down only a few feet, into river gravels and fairly modern deposits, and you'll find all these big creatures in this region, from their fossil bones. But because of some change of climate and other conditions that we don't clearly understand, most of them left this region and moved south into the projecting regions.

One of the oddest results of this emigration is that today the tapir is found alive on the island of Sumatra, and also in Central America. At one time naturalists were greatly puzzled to find a tapir in the New World like the tapir in the Old, and nowhere else but in these small spots, far apart from each other. Now we know that tapirs once lived all over the Holarctic region, because we find their fossil remains there, recognizing them by the shape of the teeth and bones we dig up. Tapirs are found even in England, in Suffolk, in the deposit known as the Red Crag, and in parts of Germany, France and Greece, and even in China and North America, buried in sands of Pliocene and Miocene age. The tapirs living today in the East Indies and Central America are, so to speak, the outlying survivors of the ones that once lived all over the great Holarctic region.

Facts like these about the tapir show how important it is to know where particular fossil animals are found, because they let us draw conclusions about how the different land surfaces of the world were once connected with one another.

The question must have occurred to many of you: How do we recognize pieces of bone found in the earth? How do I know that a fragment I find is the lower jaw of a creature like a horse, or that some bones I dig up belong to a tapir? How do I know that a particular skull is a reptile's, and that a particular shell was lived in by a creature like the nautilus?

We can know these things because the shape of each part of each kind of animal is very constant. Kinds that are alike in other ways are alike in the details of their bones and teeth too, right down to such tiny points as the microscopic texture of the bone. A huge mass of facts about such things is known, and when it is set out in order it is called the science of comparative anatomy, or animal morphography.

The first photograph I have to show you in this chapter is of a piece of bone that was sent fifty years ago to Professor Owen by a gentleman in New Zealand who had lately settled there and had found it in his garden. Professor Owen examined it and could say from its general make and structure that it was a bird's bone. It was about seven or eight inches long (Fig. 43). Studying its ridges and various marks, Owen was able, from his knowledge of how bones are built, to say that it matched the middle part (the ends had been broken off) of an ostrich's thigh bone. He then ventured to publish the claim that this bone proved there had once lived in New Zealand a huge bird that walked on the ground like an ostrich, only bigger. A few years later more bones arrived from New Zealand and entirely confirmed what he had said, and within a few years more he was able to put together from the bones he was sent a skeleton with enormous legs and neck: the skeleton of the ostrich-like Moa of New Zealand. In Fig. 44 you can see Professor Owen himself standing beside the restored skeleton. Since then a great many of these birds have been found buried in the swamps and fairly recent deposits of New Zealand. They show that many moas were still alive some five or six hundred years ago, and that they were then probably hunted out of existence by the ancestors of the present-day Maoris. I'll have a little more to say about the giant birds of New Zealand in a later chapter.

In Fig. 45 we have a photograph of a very fine preparation in the Natural History Museum showing the skeleton of a man and a horse side by side. The main point of the comparison is to show that, different as they are in bearing and shape, all the bones of a man match those of the horse in detail. The horse's thigh bone and the man's thigh bone correspond, and so do the horse's knee (called the "stifle") and the man's knee. The man has a short foot and the horse a long one. The part that sticks up at the back of a horse's leg, called the "hock," is really the heel, and matches the heel bone you can pick out in the man's skeleton. The forearm and shoulder blade correspond in the two skeletons as well.

Animals, then, can be sorted into divisions and subdivisions by how alike or unlike they are in the details of their structure (see the list of classes at the end of Chapter One). There are certain marks that make it easy to recognize pieces of bone, dug perhaps out of a quarry or a railway cutting, and to tell at once what division or kind of animal they belonged to. I've already mentioned that the strata of the earth are laid open to us by cliffs on the seashore, by bare rocks and by river banks, and I would add, by human works such as quarries and railway cuttings. Suppose you find a skull in such a digging. There are marks that tell you whether it belonged to a mammal or a reptile.

In Fig. 46 I've photographed the whole of the back part of a skull, the part that held the brain, and you can see where the spinal cord entered the skull to join the brain. In this creature (an ox) there are two bony surfaces (marked Ex, Ex) forming the joints, or condyles, of the skull, by which the first neck bone, or vertebra, was fastened to it while still allowing the head to turn. Every mammal's skull has this pair of knobs, or "condyles." But in the crocodile's skull (Fig. 47) you'll see that below the opening for the spinal cord there is only one large condyle (marked Bas). From a piece of skull like this, then, you can tell at once whether to put the creature it came from among the hairy warm-blooded four-footed animals called mammals, or among the reptiles. A bird is like a reptile in having a single joint, or knob, at the back of the skull.

Here is a curious example of the definite marks by which bones can be assigned to their proper classes. Fig. 48 is a drawing of the internal ear of a man, the soft part of the ear inside the head, embedded in bone. It consists of three looped canals and a coil like a snail shell. All hairy mammals have this snail-like coil in the internal ear. Fig. 49 is a photograph of the ear bone of a mammal's skull cut through, and you can see the space for the snail-shaped soft ear, the cochlea, or inner spiral of the ear, as it is called. No animals except mammals are known to have a spiral internal ear, and all known mammals have one. If you found a piece of bone with this spiral space in it, then, you would know that the bit of bone in all probability came from a mammal.

At the beginning of the nineteenth century part of a great, long skull was brought from America to Europe, dug out of the sands of Florida. It was thought to belong to a reptile like the crocodile and was named Basilosaurus. But the naturalist in charge of it, showing the specimen to a friend (Hermann von Meyer), dropped it on the stone floor of his museum and cracked the back of the skull. The crack laid open the spiral cavity, the cochlea, of the ear, and that showed the specimen to be the skull of a mammal. Sure enough, it later turned out to be the skull of a kind of whale (Zeuglodon).

Teeth are a great help in deciding what sort of animal a fragment belongs to.

Fig. 50 is a photograph of a specimen prepared in the Natural History Museum. Where teeth are concerned, the wild boar or pig holds a sort of central position among the mammals (the hairy warm-blooded four-footed animals). Its teeth are such that you can refer the teeth of every other mammal to them as to a standard pattern. In front, in both upper and lower jaw, there are three middle teeth on each side, chisel-like teeth, the incisors. Beyond these are the great canine teeth, and then come the cheek teeth. There are seven of these: four in front, which are replaced (that is, second teeth come in to take the place of the first ones), and three behind, which are never replaced. If you look at the surface of these cheek teeth you'll find they are broad, with many knobs, made for grinding up all sorts of food. Seven cheek teeth on each side of each jaw, upper and lower, plus one canine and three incisors, make eleven on each side in the upper jaw and in the lower, or forty-four teeth in all. That is the complete number, the typical number, the number most characteristic of the group of hairy mammals. Many have fewer, but among the immediate ancestors of the mammals with a "reduced dentition" we find more teeth, and in their remote ancestors we find the complete typical number.

It is important to notice that while the front teeth are set in the jaw by a single fang, the cheek teeth have two fangs, as Fig. 51 shows. Teeth with two fangs seem to belong to mammals alone. Other animals have a single fang to every tooth, as mammals (as a rule) have for their incisors and canines.

Human teeth (Fig. 52) are fewer. On each side, above and below, there are only two incisors, then the small canine, or dog tooth, and then five cheek teeth, or "molars," two smaller and three bigger. From a single tooth we could tell whether a piece of jawbone belonged to a man or not. A man's tooth is like a monkey's, but it can be told apart from a monkey's and from every other kind. In the next figures we have photographs showing some of the ways mammals' teeth are modified. You can see in the clouded tiger (Fig. 53) that the teeth are few and sharp, for cutting or tearing flesh, and that the canines are very large.

In Fig. 54 the skull of a great rat, as big as a beaver or a fair-sized dog, is photographed. Its front teeth (only one on each side, above and below) are chisel-like and very large, so that the rat can gnaw wood.

In reptiles there are no complex cheek teeth any more. All the teeth are pegs. They have no grinding teeth with broad surfaces, and every tooth has a single fang (Figs. 55 and 56).

The fossil jaw in Fig. 57 came from Stonesfield in Oxfordshire. It is set in hard Jurassic slate and is one of the most ancient pieces of evidence that mammals existed. One look at its double fangs made it almost certain that the teeth were a mammal's, and the whole shape of the jaw is like that of a small mammal such as the hedgehog.

Now we must pick up the general story of extinct animals again. To do that we'll first go back, so to speak, a little way down into the strata laid down on the earth's surface, just far enough to take us beyond the reach of written history or record, which hardly goes back further than four thousand years.

Recent explorations in ancient cities, in Egypt and other parts of the East, have brought out of layer after layer of rubbish and mud all sorts of human remains: tools, vessels and works of art. The deeper you go, the more you find remains that show different habits and ways of life. But all of these lie practically within the historic period. Beyond it we come to a period with no tradition or written record, which we know only from the remains we find: flint tools, carvings, and now and then some human bones. The most important prehistoric remains of man take us back, judging from the positions they are found in, some 150,000 years. These remains, found in river gravels in England, France and other countries, prove that man lived here as a primitive hunter alongside the mammoth, the rhinoceros, the hyena, the cave lion and the cave bear.

Fig. 58 shows two flint tools that these people made and used. A flint tool of this kind was found more than a hundred years ago in the gravel of Gray's Inn Lane in London, and was drawn and described, but nobody realized at the time how very old it was.

In the middle of the last century a French antiquary, M. Boucher de Perthes, drew attention to these flint tools found in the gravel of the river Somme. He collected enormous numbers of these worked flints around Abbeville and Amiens and insisted that they were made by men. From the depth of gravel they lay under, they were clearly of enormous age. The matter was carefully investigated at the time, geologists and naturalists took a keen interest in it, and the great antiquity of man in Europe was established. Besides these tools in the gravel, others have been found in caves, together with (as in the gravel) the remains of animals that have long since vanished from this part of the world: mammals such as the reindeer, the hairy rhinoceros, the great Irish stag, the cave bear, the cave hyena and the lion. Huge wild cattle, such as the Aurochs or Urus of Caesar, and the bison, lived then in great numbers. In some places the actual bones and skulls of these early people have been found with the bones of extinct animals.

The skulls of early men and of modern men differ somewhat in shape. If we take two skulls, a man's and a monkey's (Fig. 59), and draw a line from the point just above the nose, between the ridges of the brow, back to the ridge at the back of the skull, the human skull has a great domed hemisphere above the line, while in the monkey the space above it is much flatter and much shallower.

The incomplete skull of the so-called Pithecanthropus, or monkey-man, was found not long ago in a river gravel in Java. In its main features it is really a human skull. You can see a photograph of it in Fig. 59, the middle one of the three. Its upper part is shallow, much like a monkey's. Other shallow skulls of early men have been found in caves, such as those at Spy in Belgium, and in the sand of the Neanderthal valley on the Rhine. It seems certain that early man had a shallower brain than later man. But some of the prehistoric people seem to have been able to draw, and to have shown great skill at it. It's hard to say whether more than one race was around at this time, and whether the men with the shallow skulls were the same men who made the drawings. In one of the caves of France where prehistoric people lived, thickly strewn with their chipped flints and the bones of the extinct animals they ate, a piece of mammoth tusk has been found with a mammoth carved on it (Fig. 60), plainly by the people who lived there. We also find reindeer heads carved on pieces of bone. The pictures in Figs. 60 and 61 are photographs of drawings of the actual specimens. Fig. 61 shows a piece of antler with a reindeer cleverly outlined on it. The tuft of hair under the chin is there, and the big feet and extra toes are correctly drawn. Clearly the men who drew this reindeer lived with the reindeer. And living with those men in the south of France, besides the reindeer, was the great mammoth.

The mammoth was like an Indian elephant, but with a coat of coarse hair, and its tusks curved a little differently from the Indian elephant's. It was a little bigger than the biggest Indian elephant.

The mammoth has left its remains all over the Holarctic region. Even in our own country we keep coming across tusks and teeth. In the Natural History Museum there is a whole skull with enormous tusks that was dug up in a brick-field at Ilford, in East London, about twenty-five years ago. When I was a boy I used to get plenty of remains of mammoth, rhinoceros and hippopotamus from that brick-field. When the workmen found this mammoth skull, the British Museum authorities of the day sent a man down to remove it with the greatest care, and it is now at the Natural History Museum.

The remains of the mammoth are found in huge numbers throughout the Holarctic region. This enormous beast probably survived later in Asia and Siberia than in our part of the world. In northern Siberia whole carcasses of the mammoth, and of the hairy rhinoceros too, are found frozen, with the skin, hair, trunk and soft parts complete.

At the beginning of the last century one of these frozen carcasses was taken to the Museum at St. Petersburg. It is from this specimen, drawn in Fig. 62, that we know the mammoth had a hairy skin.

Interestingly, the newborn young of both the Indian and the African elephant have a full coat of fairly long hair, which disappears within a few weeks. The mammoth isn't really peculiar in this respect, then.

Fig. 63 shows the skeleton of the largest and most beautiful of all the deer tribe. It is extinct now, but it survived later in Ireland than anywhere else, and in great numbers there. Its bones are found in the mosses and bogs of Ireland.

It lived at the same time as early man, and perhaps survived in Ireland until nearly historic times. Why it died out there is hard to explain.

Since our explorations of river gravels only twenty or thirty feet deep have brought us face to face with the mammoth, I'd like now to say more about living and extinct elephants and take a look at the past history of the elephant tribe.

Fig. 64 is a careful restoration of the hairy mammoth as it must have looked in life, and Fig. 65 is a photograph of the Indian elephant from life. Notice the Indian elephant's fairly small ear and high forehead.

Fig. 66 is a photograph of the African elephant from life. It has a longer head and a much larger ear than the Indian species.

The biggest Indian elephant is very seldom as much as eleven feet high at the shoulder. But some African elephants must grow to twelve and possibly thirteen feet, to judge by the size of their tusks.

Fig. 67 shows two elephant tusks; both specimens are in the Natural History Museum.

One is a very fine Indian elephant's tusk weighing seventy-two pounds, as big an Indian tusk as you'll find in any museum. The other is an African elephant's tusk. It is ten feet two inches long and weighs 228 pounds. It is the biggest tusk ever seen in the ivory market, and it was bought for the Museum in 1900. Elephant tusks have been imported from Africa for many years, and none has ever come near this one in size. Anything around 150 pounds is thought enormous, and this one weighs 228 pounds. It came from Zanzibar ten years ago and is one of a pair that probably formed part of the hoard collected by Emin Pasha.

In Fig. 68 we have the skeleton of a creature very like the true elephant, except that its teeth are a little different and its head and jaw are more "snouty," or long. It is the American mastodon. Compare its skeleton with the mammoth's in Fig. 62 and with the Indian elephant's in Fig. 69.

In the United States (in Ohio and other places) very complete remains of this enormous creature have been found in bogs and swamps that are probably no older than the peat bogs of Ireland where the great Irish stag is found. Man certainly lived at the same time as some of the American species of mastodon. But in Europe no mastodons survived to so late a date. Other, older species of mastodon seem to have come before the elephants in Europe, Africa and Asia, and in fact to have been the ancestors from which the elephants came.

Chapter Three: The Ancestral History of Elephants—Extinct Horses and Rhinoceroses—The Arsinoitherium

Compare the American mastodon with the true elephants, that is, the African, the Indian, and the Holarctic one called the mammoth, and you find first of all that although the mastodon is as big a beast as any of them, and very close to them in the shape and arrangement of its bones, there are two important differences. One is the shape of the head; the other is the shape and number of the teeth. Look at an elephant's skull (Fig. 70) and compare it with a dog's (Fig. 71) or a pig's, and you'll be struck by how abruptly the bones of the face are set. As far as the bony parts go, the face is almost flat; both upper and lower jaws are quite short. There is, in fact, no "snout" at all in the bony skull. This extreme shortening, or pushing in, as it were, of the face is like what has happened in bulldogs and pugs compared with ordinary long-snouted dogs, as Fig. 71 shows, only the elephant carries it further than any dog. We can call this shortening of the face "bulldogging." This "bulldogging" of the skull turns up in a South American breed of cattle called the Niata breed. It seems that the ancestral elephants must have had a long face and a bony snout like other animals, and that their descendants have gradually become "bulldogged." The mastodon's skull (Fig. 72) has much more of a projecting bony face, or snout, than the elephant's, and this would lead us to think that the mastodons are more primitive than the true elephants, that is, more like the ancient ancestors of elephants. An interesting fact here is that the newborn elephant has a more "snouty" skull than the grown-up elephant, as Figs. 73, 74 and 75 show. Very young animals often have features that recall their ancestors and that disappear as the young creatures grow to full size.

The American mastodon is more primitive than the true elephants not only in its longer face. Its teeth too are less peculiar than true elephants' teeth, and closer in number and shape to those of the ordinary, more central kinds of mammals, such as the pig (see Fig. 50 in the last lecture). The elephant has two enormous incisor teeth at the front of its upper jaw: the tusks. There are no matching teeth in the lower jaw. Then comes a gap in the row, and after it the cheek teeth, which are very strange. The jaws, upper and lower, are so short and the teeth so big that there is only room for one tooth, or a tooth and a half, on each side above and below at any one time. An elephant only ever has three full-sized cheek teeth on each side above and below (twelve in all), and these push forward from behind: the first wears out and is pushed forward as the second comes forward, and the second in its turn wears out and disappears as the third pushes into place from the back of the jaw. Three little "milk teeth," or first teeth, of the molar series come before these on each side above and below, and are lost one after another between the second and fifteenth years of life. The first big molar comes into place in the fifteenth year and lasts for ten years, when the second, which is already showing its crown in the twentieth year, takes its place. The third comes forward in the same way about twenty years later.

The molars of the Indian elephant and the mammoth have a great many narrow ridges set crosswise on the crown. As many as twenty-seven of them can be counted on the biggest molar when it is in place, and the whole surface is worn by grinding. Fig. 76 shows the ridges on the teeth, though not the full number, since the front tooth has been worn down and the back one hasn't yet brought all its crown into use. Fig. 77 is a photograph of the lower jaw of an African elephant. Only one big molar on each side is in place, and it has eleven crosswise ridges. That is the most the African elephant ever has. Comparing the figures, you can see that the African elephant's ridges are much wider than the Indian's. The matching tooth of the Indian elephant, because its ridges are narrower, would have twenty-seven of them showing once it was fully "cut." Now, there's no doubt that a large number of narrow ridges is a late, special feature of the elephants. With fewer crosswise ridges their cheek teeth would be more like those of pigs, tapirs and bears. And sure enough, fitting the view that the mastodons are more primitive than the true elephants, we find that their cheek teeth have very few crosswise ridges, from two to five (Fig. 78), and that the jaw is relatively longer, so that there is room for two complete molar crowns on each side at once, or even three. This brings us nearer to the central or "typical" state of mammals' teeth, which, as we saw in the pig (Fig. 50), has seven cheek teeth in place on each side of each jaw at once; the front ones are second teeth that had milk teeth before them, while the three big back ones had none. Tracing the ancestry of living mammals back through extinct ancestors of succeeding geological ages, we expect to find that even the strangest and most oddly altered creatures (the elephants with their teeth and jaws, say, and the horses with their toes) were preceded by forms that bring us nearer and nearer, the further back we go, to a sort of common form, or "type," of the mammal group: a hairy creature with five toes on each foot, the typical set of teeth (three incisors, one canine, four premolars and three back molars on each side of each jaw), and three or four knobs on the crowns of the molars. And we don't expect this remote ancestor to have been very big, not much bigger than a dog, since great size is a special feature that implies a long reign at the top.

The American mastodon is like the ordinary run of mammals in another way that the elephants are not: when it is quite young it has front teeth, a single pair, in the lower jaw. These drop out in the American mastodons. But here is a photograph (Fig. 79) of the skeleton of a much older mastodon, dug up in France in strata of the Middle Miocene (that is, below the Pleistocene, below the Pliocene, and below the Upper Miocene too). The skeleton is kept in the Museum in Paris, where the photograph was taken. You'll see that its head differs in many ways from those of the elephants and the late American mastodon. It has an extraordinarily long lower jaw with two tusks in it. Fig. 80 is a drawing of the side of the skull, and you can see how the two level lower teeth must have worked between the two curious downward-bent tusks of the upper jaw.

I must mention in passing a mastodon-like creature of the same age that had no tusks in its upper jaw but two huge tusks in its lower jaw, which is bent downward. This is the Dinotherium, found in the Miocene in Germany and elsewhere. It seems to have left no modern descendants and is a sort of extinct side branch of the elephant family. It probably used the big tusks of its lower jaw for raking up roots in the mud of rivers and lakes.

The Miocene mastodon with the long lower jaw is called Tetrabelodon angustidens. Some years ago, examining its skeleton, I came to the conclusion (as indeed anyone must) that it couldn't have had a hanging trunk like an elephant's, of the kind the short-jawed mastodons certainly must have had. Its "trunk" must have lain flat along the long lower jaw between the upper tusks. In fact it wasn't a "trunk" at all, but a lengthened upper lip (Fig. 82), the middle part of the upper jaw in a soft, flexible form. It seemed likely to me that this is how the elephant's trunk began: first the lower jaw and the upper lip and jaw grew very long, and then the lower jaw shrank and the bones of the face became bulldogged. The long middle part of the face, no longer held up by a long lower jaw, would gradually droop as the lower jaw grew shorter and shorter over the ages, until at last it hung straight down as a trunk.

In Fig. 83 I've tried to show this long-jawed mastodon (Tetrabelodon) opening its mouth and rearing its flexible, boneless upper jaw, as the living elephant rears its trunk (Fig. 84). It's very hard to form a clear idea of how the Tetrabelodon used its tusks and its flat "trunk." The upper tusks have a sharp edge along the inner face, strengthened with enamel, so they probably worked against the tough skin pads of the lower jaw to cut up plant food.

My friend Rudyard Kipling has given a different account of how the elephant got its trunk. He declares it was made by pulling the nose of an unfortunate young elephant which, in the days before trunks, stopped to drink at a pool and was seized just about the nose by an enormous crocodile.

The elephant pulled and the crocodile held on, and the elephant's nose stretched until it became a trunk. Mr. Rudyard Kipling was not told this story by the boy Mowgli of the Jungle Book. Mowgli, I'm sure, must have heard the history from the elephants as I have given it here, unless, as is quite likely, they have forgotten all about how their trunks grew, and would reject, as most men and women do, the notion that they are descended by slow change over long ages from other, simpler animals.

The history I've suggested, of the elephant being gradually produced in the later ages of the world's history from a long-jawed creature, has been wonderfully confirmed by discoveries made in Egypt in the past four years by my friend Dr. Andrews, of the staff of the Natural History Museum. Four years ago Dr. Andrews was in Egypt for his health, and he joined a party of officers of the great survey of Egypt, organized by Lord Cromer, on a visit to the Great Western Desert. This is the rainless, sandy waste west of the Nile, not very far from what is now called the Fayum, where in Roman times lay the great Lake Moeris, now dried down to a mere brine pool, in whose salt water the freshwater fishes of the Nile still live. The surveyors meant to work out the geological age of these sands, which stretch for hundreds of miles and often rise into cliffs cut sharp by the wind, showing level layers. Some pieces of bone had been reported from this region twenty years ago by the traveller Schweinfurth, and Dr. Andrews, a special expert and authority on reading fossil bones, hoped to collect some specimens for the Natural History Museum. He was rewarded far beyond his hopes. The party had to travel into absolutely waterless desert, setting up a train of camels that brought water every day as far as three days' march into the sandy wilderness and went back with empty tanks on their backs to fetch more. Fig. 85 reproduces one of the many photographs Dr. Andrews took. It shows the flat sandy desert with some fossilized lumps lying in the sand, the remains of trees. The geologists decided that the sands in this region were of Upper Eocene and Miocene age, and Dr. Andrews brought home from them some very interesting bones. Among them were the remains of a more primitive mastodon than any known before, and of an animal he called Meritherium (after Lake Moeris), the connecting link between the elephants and the central mammals with typical teeth. But the collection also included remains of great carnivores, of a Hyrax of great size (like the Syrian coney), of sea-cows (Sirenians), of tortoises, and of a snake sixty feet long. Since then the Egyptian Survey has, with the greatest enthusiasm, sent further expeditions into this desert to collect the bones of the extinct animals lying half buried there. Dr. Andrews, on the instructions of the Trustees of the British Museum and helped further by a generous gift from Mr. de Winton, has camped out in the desert twice more in later years and dug the sands with a team of local diggers.

For the history of elephants, the upshot of Dr. Andrews' very important discoveries is that we find living here in the Upper Eocene period (older than the German or French Miocene with its Tetrabelodon) an elephant ancestor of the mastodon kind, which Dr. Andrews has named Palaeomastodon. Skulls and many limb bones of this interesting creature have been found, and they now rest partly in Cromwell Road and partly far away in the fine Museum of the Egyptian Survey in Cairo. Fig. 86 gives a drawing (No. 4) of the skull of this Palaeomastodon. The figure includes several other elephant forms: the skull and lower jaw of Tetrabelodon (No. 3), of the American mastodon (No. 2) and of the Indian elephant (No. 1). You can see at once how neatly the Palaeomastodon skull fills in the series leading back from the bulldog-faced elephants with their short jaws to ordinary mammals. It has a fairly long skull and a long bony face, with two large, but not very large, downward-pointing tusks. The jaws are long, though the lower one is not so extremely long as Tetrabelodon's (No. 3), and the cheek teeth are present in nearly their full number, as many as five in each half of each jaw. They show well in the view of the lower jaw in Fig. 87 (No. 2), where the lower jaw of Palaeomastodon is clearly contrasted with Tetrabelodon's (Mastodon angustidens, No. 3).

In Palaeomastodon, by going as far back as the Eocene strata, we have reached an ancestral elephant-like creature that joins the elephant stock on to more ordinary, "normal" mammals. I should say this beast was not so very big, about the size of a fair-sized horse. Dr. Andrews' great triumph, though, is the discovery of a somewhat smaller animal in the same deposits, which is beyond doubt an elephant and yet at first sight looks nothing like one. It probably had no trunk at all, and it certainly had only small tooth-like tusks, not worth comparing with the great ivory columns of later elephants. This is the Meritherium, seen in Fig. 86 (No. 5) and shown more fully in Figs. 88 and 89. As you can see at once, the skull of Meritherium doesn't suffer from "bulldogging" in the least. It has a fine, well-developed face, and its teeth are neither short in number nor greatly exaggerated one by one. Its "dentition" (that is, the full count of its set of teeth) comes close to that of the central mammals with typical teeth. In the upper jaw (as Fig. 88 shows) there are six front teeth, or incisors, and it is the second of these on each side that is enlarged and is, so to speak, going to become the great tusk of the elephants. In the lower jaw there are four front teeth (see Fig. 87, No. 1). In the upper jaw there is also a small canine, or dog tooth. After the incisors, the cheek teeth are fully present in both upper and lower jaw, six on each side of each jaw, only one short of the typical number. And yet these cheek teeth are quite plainly, recognizably mastodon teeth. They have the crosswise ridges of the mastodon tooth (two or three) and are like mastodons' teeth in other ways too.

Here, then, we have reached a form that was certainly a close relation of the ancestors of all the elephants, if not that ancestor itself, and in it we see where the elephant's peculiar build came from. From this fairly ordinary, pig-like Meritherium the wonderful elephant, with its upright face, its hanging trunk and its huge spreading tusks, has been produced gradually, step by step. And we have seen at least some of the steps in between: the lengthening of the jaws and the growth of the incisors in Palaeomastodon, carried still further in Tetrabelodon, followed by the shrinking of the lower jaw and finally the development of the middle of the face and upper jaw into the drooping, wonderful, grasping trunk.

That's enough about the "great sagacious elephant" and his extinct relatives. Let's turn for a few minutes to the most beautiful of all animals and the most useful to man: the horse, nobler, as he is bigger and stronger and more beautifully made, than man's other animal companion, the dog. The horse is curiously unlike the central, typical mammals in having only one toe on each foot instead of five, and in the complicated pattern of his teeth. But enormous numbers of extinct horses and horse-like creatures have been dug up, and we now know quite clearly every stage leading from living horses back to four-toed and in the end five-toed ancestors. First I'll show you a photograph of a very beautiful model of an English thoroughbred (Fig. 90). There is a set of these models, of horses and of cattle, in the Natural History Museum, each carefully modelled at one-fourth life size. They were made by a Hungarian artist for the exhibition at Budapest some years ago, and we ought to have a series like it made now in England of samples of all the best breeds. It is the only way of keeping a really complete and satisfactory record, and models of known horses and cattle made today would be of immense interest and value in fifty years' time. But they are costly things to make, and only the rich owners of racehorses and pedigree bulls can undertake them.

Fig. 91 shows us the fore and hind foot of the horse. As photographers and the people who make drawings and lantern slides so often do, the artist has put the hind foot in front and the front foot behind. The hind foot (the one on the left) shows the heel bone, or "hock" (the calcaneum), standing out at the top of the ankle. Below it you can see the three bones that make up what is called the digit, as in our own toes and fingers. Then there is a long bone, the metatarsal. In the front foot the matching bone is called the metacarpal. Above these are several short bones jointed together: the tarsus, or ankle, and the carpus, or wrist (the so-called "knee" of the horse's foreleg). The horse, you see, walks on the very last joint of its toes and holds the foot and the hand upright, so that the heel is right above the toe instead of behind it as in us and in bears. On either side of the long bone of both fore and hind foot you'll see a small, long, narrow, delicate bone. The nearer of these delicate bones doesn't show very clearly in the photograph, but you can still make it out. These delicate "splint bones," as they are called, are all that is left in the modern horse of two extra toes. There was a time when horses had three toes. Far back in the Miocene strata we find horses that had three well-developed toes, each with a hoof resting on the ground (Mesohippus and Anchitherium), and earlier still a horse-like creature (Hyracotherium) with three nearly equal toes on the hind foot and four on the front foot (Fig. 92). In the Pliocene of Europe we find a three-toed horse known as Hipparion (and a similar kind is dug up in America), with three toes on each foot; but the side toes were getting small, like the "pettitoes" of the pig, of cattle and of the reindeer in fact. They didn't touch the ground (Fig. 93), and were plainly on their way to disappearing, leading to the one-toed modern horse whose splint bones are the only things left of the two outer toes. Now and then a living horse is born with two complete little toes, with hoofs, attached to the splint bones, one on each side of the big central toe, "throwing back," as the expression is, to its three-toed ancestors. Beyond the stage with four equal toes on the front foot and three on the hind foot, which a quite small horse-like creature, the Hyracotherium of Figs. 94 and 95, displays, we can trace the horse's pedigree back to a five-toed ancestor, the Phenacodus (Fig. 96). The later stages of this history, from Mesohippus to the modern horse, have been followed through very plentiful fossil remains of many steps, or stages, in the gradual change. There has been not only a gradual change from the three-toed to the one-toed state, but also a great increase in size, and the cheek teeth have grown more and more complicated in the pattern they show when they are worn down. Fig. 97 shows the crowns of the cheek teeth of Mesohippus, and Fig. 98 the crown of an upper molar of a modern horse. The changes in the teeth and toes of the ancestral series of horses have a great many interesting details that are beyond my scope here, but you can study them on specimens of a variety of ancestral horses set out for the purpose in the Natural History Museum.

The rhinoceroses of today (the one-horned Indian rhinoceros and the two-horned African rhinoceroses, one with a pointed upper lip and the other with a square, broad mouth) were preceded by a whole regiment of extinct rhinoceroses whose bones and skulls are dug up in the Pleistocene, Pliocene and Miocene strata. Fig. 99 shows the complete skeleton of the commonest kind of fossil rhinoceros, the one whose skull was dug up in London the other day and is shown in Fig. 5. This rhinoceros had a hairy coat like the mammoth, and is sometimes found with the mammoth in frozen gravel in Siberia. The living rhinoceros most like it is the African square-mouthed rhinoceros, or Burchell's rhinoceros (Rhinoceros simus), misleadingly called the white rhinoceros at times (Fig. 100). Many of the extinct kinds of rhinoceros had two horns, one behind the other, like the African rhinoceros. A rhinoceros horn is truly horny stuff, and fibrous. It is not bone, as the horns of stags are, nor does it have a core of bone, as the horns of sheep, cattle and antelopes do. Sometimes, though, there is a fair-sized boss of bone that makes a sort of base, or pedestal, for the horny horn. One great extinct beast related to the rhinoceroses, the Elasmotherium, carried a great horn on a huge boss in the middle of its head instead of on its nose. And in the Miocene of North America complete skeletons have been found of an enormous creature related to the rhinoceroses that had a pair of horns perched side by side on its nose, instead of one in the middle or two one behind the other. The skeleton of this great beast, called Titanotherium, is shown in Fig. 101, and Figs. 102 and 103 give photographs of the skull.

As big as the rhinoceros, but with quite different bones in its wrists and ankles and quite different teeth and horns, are the extraordinary creatures called Dinoceras, whose whole skeletons have been dug out of the Upper Eocene of Wyoming in the United States. As many as two hundred individuals were studied by Professor Marsh, who has written a large treatise on them. These creatures had three pairs of horns on top of the head (Fig. 104) and a pair of great tusks formed from enlarged upper canine teeth. The horns are outgrowths of the bone of the skull and were probably covered by hardened skin. Fig. 105 shows how the creature probably looked in life.

A very interesting fact has been noticed about the brains of these most ancient big mammals, the Dinoceras from as far back as the Upper Eocene and the Titanotherium from the Lower Miocene. We can take casts of the inside of their skulls and compare them with casts from modern rhinoceroses, hippopotamuses and horses (Fig. 106). It turns out that although Dinoceras and Titanotherium were bigger than the largest rhinoceros alive today, their brains were quite small, no more than an eighth the volume of those of the modern big animals. The subject hasn't yet been looked into as fully as it deserves, but it seems that modern animals, the animals that have survived, have much bigger brains than those that died out in Eocene and Miocene times, and it is likely that they survived largely because a bigger brain was worth so much to them in the struggle for existence.

It seems that a small brain may do very well for steering the great animal machine along its established ways, but to learn new things in its own lifetime an animal must have a big brain, in fact a very big brain. And the kind of animal that can learn, that is, that can be educated, will in the long run beat the kind whose brain is too small to be capable of learning. That is the meaning not only of the big brains of the modern rhinoceros and horse compared with those of Titanotherium and Dinoceras, but also of the big brain of man, which is far bigger than any other animal's in proportion to the bulk of his body and limbs.

Another huge horned animal has come to light quite lately that is like Titanotherium and Dinoceras in some ways, but has to be kept apart from them, because it is really unlike them in its teeth, skull and foot bones, though it has their general outline and bulk. This creature was found only three years ago in the same Upper Eocene sands of the Egyptian Fayum where Dr. Andrews found the ancestors of the elephants. The skull of this very strange animal is shown in Fig. 107, and our idea of how it looked in life is given in Fig. 108. This wonderful beast was discovered by Mr. Beadnell of the Egyptian Geological Survey, and he gave it the name Arsinoitherium because the Egyptian queens of Greek descent, called Arsinoe, had a palace near the place where the bones were dug up. Two thousand years ago much of what is now sandy desert was well watered and farmed. The drawing in Fig. 107 is made from a skull in the Natural History Museum, where we have brought together parts of several other skulls and the complete set of bones of the skeleton, dug up some by Dr. Andrews and some by the energetic officers of the Egyptian Survey. The huge pair of horns are entirely bony outgrowths of the nose bones, and they are hollow. A small second pair of horns sits behind them. In life the big horns were probably sheathed in horn, like the horns of a bull or an antelope. The teeth are most remarkable, because they form a complete row without a break, present in the full number (seven cheek teeth, a canine and three incisors on each side of both upper and lower jaw), wonderfully graded in shape and size.

A complete account of this most remarkable beast, whose skull alone is nearly three feet long, will soon be given, with illustrations, by Dr. Andrews in a large volume on the extinct animals from the sands of the Egyptian Fayum, which is now being prepared and will be published by the Trustees of the British Museum.

Chapter Four: Extinct Giraffes and the Okapi—The Giant Sloths of South America and the Giant Kangaroos of Australia

There are vast numbers of extinct mammals, related to the cattle, sheep, goats, antelopes, deer, lions, bears and hyenas of today and to other less familiar warm-blooded, hairy, four-footed animals, besides many, such as the Dinoceras and the Arsinoitherium, that have left no successors like themselves alive in our day. You can see the bones and skulls of both kinds in the Natural History Museum, those that have died out completely and those that have living relatives today. I haven't room here to talk about more than a few extinct creatures, so I'll go straight to some members of the group we know today through the beautiful giraffe of Africa, the "camel-leopard," the spotted, long-necked creature that will very soon be killed off by the intrusion of civilized man into the African wilds.

We've already seen a photograph of the giraffe in the first lecture, its long neck reaching forward in one continuous line with its back. Today I'm showing you a sketch (Fig. 109) of what Sir Harry Johnston calls the five-horned giraffe. The ordinary giraffe has a pair of short bony outgrowths, or so-called horns, on the top of the skull, and a single horn of the same sort between the eyes. But the five-horned giraffe has an extra short pair of outgrowths at the back of the head. All these "horns" in the giraffe are covered in life with living skin. They have no horny covering, and they don't grow out through the skin as bare bone, the way the antlers of deer do. The skull of the five-horned giraffe is shown in Fig. 110. The two hind knobs, or horns, are real "outgrowths" of the skull, but the main horns (the middle one and the large pair, of which only the left one shows in the photograph) begin as separate pieces of bone, which grow for a while as bones of their own and then fuse tightly to the skull. Sir Harry Johnston shot the five-horned giraffe in the great "reserve," or protected area, formed by the crater of the extinct volcano Mount Elgon, some five miles across, in the British Central African Protectorate of Uganda. Less than three weeks after the day he shot these specimens he was in London, and brought their skins and skulls to the Natural History Museum! Central Africa, on the equator, can now be reached in that short space of time.

In Miocene times there were other large animals related to the giraffe, but without such a long neck. The giraffe family have cloven hoofs, like the cattle, sheep, antelopes and deer they are related to, not single or triple hoofs like the horse family. Besides their peculiar and very primitive horns, they have another small but definite peculiarity. The outermost of the group of eight front teeth in the lower jaw corresponds in position to the canine of the pig and other typidentate animals (animals with "typical" teeth, that is, little altered in shape and arrangement from those of the early mammal ancestors). In cattle, sheep, antelopes and deer this tooth has a quite simple chisel-like crown, like the incisors'. But in the giraffe it is very peculiar. The crown is split by a slit into two halves, each of them large and broad, and it is described as bifoliate, or two-leaved (see Fig. 111). Until the other day no other mammal among living animals was known to have this tooth shaped in this peculiar way. But a great extinct animal from India, the Sivatherium (Fig. 112), with much larger horns than a giraffe's, has the same bifoliate canine on each side of the lower jaw (Fig. 111), and by this and other features of its structure it is clearly related to the living giraffe. Another creature, from the Miocene strata of the island of Samos, the Samotherium (Fig. 113), also has the split lower canines and is closely related to the giraffes. The whole skeleton of a giraffe-like animal with a moderately long neck has been found in Miocene beds in Greece, and is called the Helladotherium (Fig. 114). Naturalists were deeply interested, then, when Sir Harry Johnston, some four years ago, obtained the skin and two skulls of a new animal, the Okapi, from the borders of the Congo State, where the great Congo forest comes down to the river Semliki, which divides Congo-land from Uganda. He rightly guessed it to be a second living genus, or kind, related to the giraffe. I gave Sir Harry Johnston's new animal the name Okapia; it is stuffed and on show in the Natural History Museum. Like the giraffe, it has cloven hoofs and a rather long neck, but it is striped on the legs and haunches instead of spotted. The most decisive evidence of its relationship is in the canines of the lower jaw, which, though small, are split or bifoliate, like the giraffe's (see Fig. 111). Our specimen (Fig. 115) is about as big as a large stag. It has no horns and is not full-grown. It is probably a female; the male, we now know, has a pair of horns (Fig. 116), and in the details of its skull is extremely close to the Samotherium (Fig. 113). Some fifteen specimens of this new and rare animal have reached Europe since Sir Harry Johnston discovered it, and there are probably two species, a smaller and a larger, both living in the forests of the Congo in the centre of Africa. Since they live in those immense, dark, gloomy and damp forests, they are very hard to shoot or catch, and besides, they aren't plentiful. The local people cut the striped skin into belts and bands for ornament. Sir Harry Johnston sent home two of these before the animal itself was known, and they were described as coming from a new species of zebra, which Dr. Sclater named Equus Johnstoni (see Fig. 117).

Because the okapi is striped rather like a zebra, while it has a giraffe's cloven hoofs and paired horns, some people have supposed that it might be a hybrid, or "mule," between a zebra and a giraffe. Every naturalist knows, though, that this notion lies outside the bounds of the remotest probability. It is a fact that "mules," or hybrids, are never produced by animals living in their natural conditions, apart from a few rare cases among water animals whose eggs are fertilized in the water after they are laid. And nobody has ever produced, even in captivity, a hybrid between two creatures as unlike each other as a cloven-hoofed and a single-hoofed mammal.

There are quite a few cases where small living animals were represented in the past by gigantic forms very close in structure to the little living beasts, only much bigger. From this it is concluded that these particular living animals are the shrunken, dwindled representatives of a race of primeval monsters. There's some truth in that, as you'll see from the history of the living sloths and armadillos of South America, compared with the giant extinct sloths and armadillos dug up there. The same holds for the kangaroos and wombats now living in Australia, compared with gigantic extinct creatures of the same kind dug up in Australia in sands and swamps of late geological date. But it's a great mistake to conclude from this that it is a law of Nature that modern animals are all small and insignificant beside their representatives in the past. That is simply not true. Modern horses are bigger than extinct ones, and much bigger than the three-toed and four-toed ancestors of horses. Modern elephants are as big as any that ever lived, and much bigger than the earlier elephant ancestors. No creature of any kind, mammal, reptile, bird or fish, in any geological period we know of, has ever been as big as some of the whales alive today: the sperm whale, the great rorqual and the whalebone whales. It is true there were enormous reptiles in the past, far larger than any living crocodile, standing fourteen feet at the loins and measuring eighty feet from the tip of the snout to the tip of the tail. But their bodies didn't weigh much more than a big African elephant's, and they were small next to whales. Let's be under no illusions, then, about extinct monsters, and go on to look at those of South America with simple courage and confidence in our own day.

South America (see the map, Fig. 42) was not so long ago a vast island, and at an earlier period it was joined to Australia. Later it joined on to North America. The animals that are its own special products seem to be the members of the group of mammals called Edentata: very peculiar forms, with strange teeth, and none at all in the front of the jaws. When it joined North America it received from there the mastodons, horses, tigers, tapirs and other kinds produced in the Holarctic region. This seems to have led to the dying out of the big kinds of Edentata, and now there are only the small tree sloths (Fig. 118), the small armadillos (Fig. 119) and the strange-looking anteaters. But in quite late geological deposits in South America we find the bones of gigantic armadillos and gigantic ground sloths, which lasted on until man appeared on the scene, though they are now extinct. A great variety of large creatures of the kinds known as Edentata came before these in earlier geological times in South America.

The Glyptodons (Fig. 120), of which there are several kinds, were enormous armadillos, as big as an ox. Like the little armadillos of today they carried a hard case made of bones in the skin, but it wasn't jointed, so they couldn't roll up into a ball as living armadillos can.

The Megatherium (Fig. 121) was nearly as big as an elephant, and in its skeleton and teeth was very like the little living sloths of today. But it stood on the ground and pulled trees down to eat the tender young branches, instead of climbing up into the trees and living there as the present sloths do.

Not quite as big as the Megatherium was the Mylodon, which lived at the same time. The remains of both are found in the fairly recent (Pleistocene) gravels of Argentina, and their skeletons can be seen side by side in the Natural History Museum.

Fig. 122 shows the skeleton of the Mylodon, and just above it, for comparison, is a photograph of the skeleton of the two-toed sloth. The two are shown at their true relative sizes, and the sloth's skeleton is posed like the extinct Mylodon's, although in life the sloth always hangs from the branches of trees and never goes on all fours on the ground.

The Mylodon, we know, had a number of little pieces of bone scattered in the skin of its back, like the pieces that make up the bony case of the armadillos and Glyptodons, but not fitted closely together. It was supposed that the Mylodon, like all the gigantic Edentata of South America, had long since ceased to exist, and had died out as long ago as the mammoth and the woolly rhinoceros of our own country. But about seven years ago a traveller (Dr. Nordenskjöld) found in Patagonia, at the head of a fiord near the Chilean coast, a vast cave (Fig. 123). From this cave the white settlers on a farm close by had taken an enormous piece of skin (Fig. 124), covered with greenish-brown hair and studded on its inner side with little knobs of bone (Fig. 125)! The skin was dry but not decayed, and when it was soaked in water it gave off the smell of rotting animal matter. It was plainly a piece of the skin of a Mylodon that had survived in this region into modern times! Dr. Moreno, of the Museum of La Plata, and others explored the cave further, and they brought out an immense quantity of bones, and more pieces of Mylodon skin with the hair on. The cave had probably been lived in several centuries ago by Indigenous people, and human bones were found, as well as "forks" made from dogs' bones (Fig. 126). The remains of as many as twenty Mylodons have come out of the cave, and many of the bones have been cut or broken by human hands: the people of the cave had eaten the Mylodons and split their bones for the marrow! Some of the Mylodon bones (skulls, jawbones, leg bones and so on) are smeared with blood and still have the soft tendon and membrane attached. The cartilage at the ends of the long bones is still in place, dried and cracked in the drying. And that isn't all. Great balls of dung were found, made up of chewed grass, showing that the Mylodons lived in the cave. Besides that, a very large quantity of cut grass was found there, and it has been suggested that the people kept the Mylodons alive in the cave and fed them on hay brought in from outside. Specimens of these things, and of others I'll mention below, are now in the Natural History Museum, and you can get some idea of how many and how varied they are from the photographs in Figs. 126 to 131.

Besides the remains of the Mylodons and of man, all lying loose under a greater or lesser depth of windblown sand, and in some places under chopped hay, the cave has given up bones and teeth and many horny hoofs of horses, apparently of the extinct and very peculiar South American genus Onohippidium; the skull and bones of a very large kind of jaguar; the skull of a young llama; and bones of other kinds. We don't yet have a full account of everything found in the cave, and unfortunately the contents weren't removed carefully enough for us to say which lay deeper in the sand and which higher up, and so lived more recently. The cave is in a very remote spot and seems to pose some peculiar difficulties for explorers, because neither Sir Thomas Holdich nor Mr. Hesketh Prichard, who set out expressly to find it, managed to reach it. There are said to be other caves of the same kind in the neighbourhood. What makes the remains in this cave so peculiar is its dry, sandy floor. The bones aren't sealed in "stalagmite," as they are in the bone caves of England and France, and while they are quite unaltered and full of animal matter, the horny and sinewy parts of many of the animals (skin, hair, claws and hoofs) and the soft dung of the Mylodon are preserved unchanged. In any known cave in Europe, remains like these would quite certainly be destroyed within fifty years by putrefying bacteria, and if conditions were too dry for that, scavenging beetles and other insects would have eaten them up within the same time. The climate of southern Patagonia, where the cave is, is like Devonshire's. It is a damp climate, although the cave itself isn't damp or liable to flooding by streams. There is nothing preservative in the sandy soil, and at first sight it seems impossible that the soft dried remains (skin, claws, blood and so on) can be more than fifty years old. Yet the horses' hoofs and bones seem to belong to the extinct Onohippidium, and the Indigenous people of today have no record or tradition (in spite of some statements to the contrary) of any huge beast like the Mylodon. Altogether the case is very puzzling, and it makes one eager for further exploration. One noticeable fact that bears on it is that the whole southern part of South America sank rapidly within the late Pleistocene period and rose again rapidly, and is still rising in some parts at the rate of two feet a year. Perhaps the rocks and high ground where the Mylodon cave lies formed an island during the sinking, where a number of animals of the earlier fauna took refuge and survived until the land rose again, and so lived on in the land as it is now until fifty or a hundred years ago. Possibly, though by no means probably, the Mylodon is still living in similar caves in this region that no one has yet visited.

In Australia, the land of the marsupials, or pouched mammals, the bones of gigantic creatures of that peculiar tribe have been found. Giant kangaroos, twice as tall as any living kangaroo, are known from them. But there are also remains of some extraordinary animals like wombats and koalas, only as big as the largest rhinoceros or a small elephant. One of these is Owen's Diprotodon, which he knew from its skull and the rest of its skeleton except the feet. The skull is drawn in Fig. 132, with a human skull beside it for scale. Fig. 133 gives Owen's restoration of the whole skeleton, without the feet. The feet have now been found by Dr. Stirling of South Australia. A number of complete skeletons of this huge beast were found buried in the mud of a great lake or swamp. The photograph (Fig. 134) shows the lake, with one of the great skeletons in the foreground. The bones were very crumbly, but Dr. Stirling has managed to preserve them and has secured the complete feet. Fig. 135 shows the right hind foot. It is expected that the whole skeleton will be put together and shown in the Natural History Museum before very long.

The oldest remains of mammals we know of are found in the Oolitic and Triassic strata, and they consist of very small lower jawbones with their teeth, set in very fine-grained rock. It is usually held, from the shape of the angle of the jaw, that they belonged to small marsupial mammals. They are very small, few of them as much as an inch long, and we have already seen one of them in Fig. 57, enlarged to ten times its real length. It is probably because they are dense and hard that the little jawbones were buried and preserved in these ancient rocks while the rest of the skeleton is lost to us. The first jawbones of this age were found seventy years ago in the Stonesfield Slate near Oxford by two undergraduates of the University, and at first it was assumed, because they came from such ancient rock as the Oolite (see the table of strata in Fig. 41), that they must be the jawbones of lizards. Soon, though, someone noticed that the teeth had double fangs, and it became clear from this, as well as from the shape of the jaws and teeth, that they had belonged to small mammals. Two of these very ancient mammal jaws are drawn in Fig. 136.

Chapter Five: The Great Extinct Reptiles—Dinosaurs from the Oolites—The Pariasaurus and Inostransevia from the Trias of North Russia and South Africa—Marine Reptiles

In the next two chapters I mean to put before you, briefly, a few examples of extinct reptiles, birds and fishes, and to take the very shortest look at the host of extinct invertebrates, shellfish, insects, starfish and so on, whose name is legion.

We'll go straight to the reptiles. You'll see from the list of groups of reptiles I gave you in an earlier chapter (at the end of Chapter One) that there are four big orders, or groups, of living reptiles: (1) the crocodiles; (2) the tortoises (Chelonians); (3) the lizards; and (4) the snakes. The lizards and snakes are so alike in their real structure that they are treated as one double order. Extinct representatives of all these orders are found all the way down through the Mesozoic strata to the Trias (see the table of strata, Fig. 41). But there's nothing very astonishing about them, except the great size of some of the extinct tortoises and snakes, and one thing about the older extinct crocodiles. All air-breathing vertebrates, ourselves included, have openings where the nose passages enter the mouth. The old crocodiles had these openings far forward, where they are in the more primitive air-breathers, whereas living crocodiles have them pushed ever so far back, to the very furthest recess of the long, ferocious mouth. Because of this the modern crocodile can have its mouth full, holding the body of a victim under water, while the air passes from the tip of its nose along the long nose passage to the very back of its mouth and so to its lungs. Primitive crocodiles didn't enjoy this convenience.

The great interest of extinct reptiles lies in those that were so entirely different from the reptiles of today that naturalists have to make separate orders for them. Many of them were huge. They flourished in the Mesozoic period and died out abruptly; at any rate, their remains vanish from the rocks at the close of the Chalk, or Cretaceous, period (see the table of strata, Fig. 41). These extinct orders of reptiles are the Dinosaurs, the Theromorphs, the Ichthyosaurs, the Plesiosaurs and the Pterodactyles. They are a prominent example of the kind of extinct animal that is not, so to speak, the forefather of living animals: the whole race, the whole order, has passed away, leaving no descendants, changed or unchanged.

To begin with the Dinosaurs. They are a very varied group and were mostly of great size. In many ways they seem to have filled the same sort of place on the earth that was filled later by the great mammals, such as elephants, rhinoceroses, giraffes, giant kangaroos and so on. Preying on the plant-eating kinds there were huge flesh-eating dinosaurs, standing for the lions and tigers of today. Yet the mammals I've mentioned are not descended from these great reptiles at all. They came from another stock, and took their place on the face of the earth only through a slow process of development, in which the great reptiles disappeared and the great mammals gradually appeared and took over.

Some of the shapes the great dinosaur reptiles took are not unlike the shapes of the small scaly lizards of today (see Figs. 137, 138, 139, 140). But on the whole the dinosaurs were more like mammals in shape, standing well up on their legs. We don't know much about their skin. It was probably smooth, with only small horny scales, as in many living lizards, and often had great horns and crests growing out of it. But we do know their complete skeletons, put together from bones chiselled out of the hard rock they are found in, and we know that in important points of shape and build the skeleton was different from that of living reptiles. How big some of the dinosaurs grew is shown by the thigh bone of one found in the United States and called Atlantosaurus, photographed in Fig. 6. This thigh bone is a third as long again as that of the biggest elephant known.

Fig. 141 shows the complete skeleton of the Iguanodon. This great dinosaur was one of the first to be discovered. As you can see, it stood on its hind legs like a kangaroo, and when running it sometimes went on those feet alone, touching the ground every now and then with its front feet. Footprints in slabs of sandstone that was once soft wet sand are found that show this. In the position shown in the figure, the animal stood about fourteen feet from the head to the ground. Its thigh bone was only three feet long, so in length it was only half the size of the Atlantosaurus.

Fig. 142 is an attempt to show what the animal looked like with the skeleton clothed in flesh and skin. The first bones and teeth of the Iguanodon were found seventy years ago by a famous and most delightful collector and explorer of the earth's crust, Dr. Gideon Mantell, in the strata known as the Wealden in Sussex, just below the Chalk and Greensand (see the table of strata). Dr. Mantell found that the teeth, two of which are shown here at natural size, belonged to a plant-eating animal, and that they were like the teeth of the little living South American lizard called the iguana in that the broad, chisel-like crown has a saw-toothed edge (Fig. 144). That is why the new fossil giant reptile was named Iguanodon ("iguana-toothed"). The bones found by Mantell and others were scattered and out of their natural places, and the shape of the creature had to be guessed at by fitting this piece and that together. But some twenty-five years ago a wonderful find was made near Brussels in a coal mine at a village called Bernissart. No fewer than twenty-two huge Iguanodons were found, complete, buried in a fairly soft, clay-like rock! The authorities of the Government Museum took charge of the place and most carefully moved the rock with the skeletons in it to the Museum workshops in Brussels, where the complete skeletons of seven were taken out of the rock bit by bit, with enormous difficulty and care, and set up as whole skeletons in the Brussels Museum, where you can see them. A cast of one of these seven is in our own Natural History Museum. Fig. 145 is a photograph of the skull of one of these specimens. It shows not only the teeth in place but, at the front, the bony supports of a great horny beak like a turtle's. As you can see in the drawing of the skeleton (Fig. 142), the forefeet, or hands, had five fingers, and the thumb carried a huge claw at least a foot long. The foot was very like a bird's and had only three toes, and the bones of the pelvis, or hip girdle, are extraordinarily like a bird's. In fact it is now certain that reptiles like the Iguanodon were the stock birds came from. The front limb probably became first a swimming flipper, or paddle, and later an organ for beating the air and lifting the creature out of the water for a short flight. From a beginning like that came the feathered wing of modern birds.

Fig. 146 shows the skeleton of a dinosaur somewhat smaller, but with the same kangaroo-like stance, that was a beast of prey. It is the Megalosaurus, and it had many tiger-like teeth in its jaws. It hunted down and ate the plant-eating dinosaurs, as lions and tigers hunt and eat antelope and buffalo today. By no means all the dinosaurs walked on their hind legs. There were enormous kinds that went on all fours. Here is the skeleton of the Brontosaurus (Fig. 147) and a sketch of how it looked in life (Fig. 148). The great Ceteosaurus, whose limb bones and most of whose skeleton were found near Oxford, is like it, and Mr. Andrew Carnegie has presented to the Natural History Museum a complete reconstruction of the skeleton of a closely related dinosaur, the Diplodocus, which was dug up in Wyoming and is now in the Carnegie Institute in Pittsburgh. It is eighty feet long. Its head is very small, and much of its length is taken up by the very long neck and the very long tail, but its body is bigger than the biggest elephant's, and its back stood nearly fourteen feet off the ground.

The immense numbers in which the bones of these huge creatures have been found in the Mesozoic strata of the United States are astonishing, and no less remarkable is the skill and success with which American naturalists, chief among them Professor Marsh of Yale and Professor Cope of Philadelphia, have collected, fitted together and drawn every detail of more than thirty different kinds of these monsters. They have given such full evidence of the structure and build of the animals that we can accept with confidence reconstructions of their appearance such as Figs. 149 and 150, which show the rhinoceros-like Triceratops and the huge crested Stegosaurus. Crests and horns like these look bizarre and grotesque even on little living lizards a few inches long, but remember that the dinosaurs drawn in Figs. 149 and 150 were as big in the body as large elephants.

A curious fact about these great dinosaurs is that, compared with big living reptiles such as the crocodiles, they had very tiny brains. You'll remember that the extinct mammals called Titanotherium and Dinoceras had brains one-eighth the bulk of those of living mammals the same size, such as the rhinoceros and hippopotamus. It was the same with the huge extinct reptiles. In some of them the head itself was absurdly small by our usual ideas of proportion, and even in others, such as Triceratops, where the bony and muscular parts of the head were big, as in a rhinoceros, the brain was incredibly small. It could have been passed all the way down the spinal canal that holds the spinal cord, and in proportion to the bulk of the body it was a tenth the size of a crocodile's. Very likely the small brains of great extinct animals have something to do with their ceasing to exist. Animals with bigger and ever-growing brains beat them in the struggle for existence.

That's all for the dinosaurs, which could well fill a whole course of lectures on their own. Now we'll turn to the Theromorphs, an even older group than the dinosaurs, which flourished in the Trias period (see the table of strata, Fig. 41). The Theromorphs get their name because in some important parts of the skull and jaw, and often in the teeth too, they resemble the mammals, or Theria. They come close to a point in the history of land-living vertebrates that is the common origin of reptiles, mammals and Batrachia, or amphibians (newts, salamanders and frogs).

Their remains have been found in the Triassic sandstones and limestones of South Africa, Russia and India, and of Scotland and the middle of England. One of the most striking is shown by a completely reconstructed skeleton from Cape Colony in the Natural History Museum, photographed in Fig. 151. The skeleton is some eight feet long and looks like a gigantic pug dog. This is the Pariasaurus, and its small teeth show that it ate plants.

From the same place we have the Dicynodon, with two huge tusks, and the Cynognathus, whose skull and teeth look wonderfully like a bear's at first sight.

Another strange crested form that belongs here is the Dimetrodon, from the Permian strata of Texas, U.S.A. (Fig. 152).

But now, thanks to the kindness of Professor Amalitzky of Warsaw, I'm able to show you a set of photographs he took of his discovery and working out of a whole series of skeletons of these Theromorph reptiles, very like those from the rocks of Cape Colony but from a place far away from South Africa: the banks of the Northern Dvina near Archangel, in northern Russia. Professor Amalitzky hasn't yet finished his excavations or published these photographs, so it is very kind of him to let me show them here in London.

First we have the cliff of Permian strata on the bank of the Dvina (Fig. 153) from which, and from another spot like it, the remains were taken. At this point, where the photograph shows a dark patch, there is a peculiar "pocket," or collection of sandy material, with large hard nodules buried in it. These nodules are dug out and broken up for mending the roads. The pocket seems to lie in a crack in the rock and to be of Triassic age, later, that is, than the Permian rocks on either side of it. However that may be, the great nodules are dug out of it for road mending, and four or five years ago Professor Amalitzky visited the spot and was astounded and delighted to find that every nodule, when broken, held the skeleton or skull of a great reptile. Fig. 154 shows one of these nodules, some eight feet long, and in this one you can easily make out the skull, the four limbs and the backbone of a large animal. The Russian geologist decided to make the most thorough investigation of this wonderful deposit, and for some years now he has spent a thousand pounds a year, raised for the purpose through the Imperial Academy of St. Petersburg, on having the nodules dug out by the peasants after their year's farm work is done, and on carrying them to the University of Warsaw. There the nodules are opened with the finest instruments and the greatest care, and each bone, which comes out in fragments, is pieced together from its more or less broken parts, firmly cemented, and set up in its natural position as part of a complete skeleton.

Fig. 155 shows the peasants at work, protected from falling stones by a shed. Fig. 156 shows some of the nodules, still unopened, lying in the geology professor's laboratory in Warsaw. Fig. 157 shows a number of skeletons of the huge but harmless plant-eating Pariasaurus that have been cleared out of the nodules and set up on iron supports as more or less complete specimens. Of course it isn't possible to get every bone out of every individual, especially the bones of the feet. Few of the animals were complete even when they were first buried in the mud ages ago. When an animal's body is carried off by a river and floats along rotting, it tends to fall to pieces.

The cliff formed by the present river Dvina is made of rocks of immense, indeed almost unimaginable, age, which existed as solid rock ages upon ages before the surface of the earth took its present form. These deep rocks have been brought near the surface by the bending of the strata (as shown in Fig. 36), and the cutting, or cliff, made by the comparatively modern river lays them open to our view and makes them easy to dig. Compared with the age of the river valley or cutting (which is probably some 150,000 years old), the nodules are as much older as Roman coins are older than the trench dug three hours ago that brings them to light. Look at the position of the Trias and the Permian in the table of strata and you'll get some idea of how immensely remote the time is when these great reptiles lived where Archangel now stands. In that table a band a twentieth of an inch thick is enough to stand for all the strata laid down since the mammoth lived in England, while the Trias lies a long way down the series: far below the Eocene, where the ancestral elephants of Egypt are found, far below the Chalk, and older than the long Jurassic series of rocks in which occur the remains of the great dinosaurs we've just been looking at.³

Fig. 158 shows one of Professor Amalitzky's Pariasaurus specimens. Nothing in this skeleton has been made up: everything you see is real bone as it was cleaned out of a nodule. Only one foot survives, but of course that tells us about its partner on the other side. The skull of another Pariasaurus is shown in Fig. 159. It is very remarkable that this species seems to be so close to the one found far away in South Africa in beds of the same age.

These Pariasaurs were about as big as full-grown cattle, but not so high on the legs. In Fig. 160 we have the skeleton of another creature these nodules have revealed. It is an enormous and truly terrible carnivore, with a skull two feet long and enormous tiger-like teeth. Professor Amalitzky has named it Inostransevia, and it is larger than any of the flesh-eating reptiles of South Africa. Its skull is shown in the Professor's photographs reproduced in Figs. 161 and 162.

No doubt the plant-eating herds of Pariasaurus, whose small peg-like teeth show plainly enough how harmless they were, were preyed on by the terrible Inostransevia, just as their cousins in South Africa were devoured by the Cynognathus, the Lycosaurus, the Cynodraco and other flesh-eating reptiles of that remote Triassic age. In these two places, Russia and South Africa, when we study the immensely remote past of the Triassic age, we find the bloodsucker and the victim, the destroying oppressor and the helpless oppressed, living side by side and forced on our attention.

We leave these great extinct land-living reptiles now and take a look at representatives of two extinct orders of huge water-living creatures that must also be classed as reptiles: the Plesiosauria and the Ichthyosauria. Though some of them must have measured thirty feet from snout to tail, they don't equal in size the great water-living mammals of today, the whales.

Fig. 163 is a photograph of the skeleton of a large plesiosaur, and Fig. 164 is a drawing of how the creature looked in life. It had a body like the hull of a submarine with four paddles attached, its front and hind legs. It had a long neck like a swan's and a long head with powerful jaws armed with many pointed teeth. It could probably swim underwater as well as on the surface, and when it was at the surface it could snap up small lizards and birds from the land. The paddles have the definite structure of legs, with five toes, a wrist or ankle, a forearm or shin, and an upper arm or thigh. A great many kinds of plesiosaurs have been found, especially in the Lias rocks of the south of England, where slabs holding whole skeletons are often found. You can see them, and the skeletons of different kinds of Ichthyosauria, embedded and flattened in the same way, in quantity on the walls of the gallery of fossil reptiles in the Natural History Museum.

Fig. 165 is a photograph of the flattened skeleton of an Ichthyosaurus. This particular species is remarkable for its very large front paddles.

Fig. 166 is a drawing of an Ichthyosaurus as it must have looked in life. The ichthyosaurs are much more fishlike, or rather whalelike, in shape than the plesiosaurs. In fact they were strangely like the porpoises and grampuses among living whales, and they stand in the same relation to land-living reptiles as the porpoises do to land-living mammals. Their fishlike look and fins are not primitive features, and they don't mean the ichthyosaurs were any more closely related to fishes than other reptiles are. They are the offspring of four-legged land reptiles that became specially altered and adapted for life under the sea. Like many whales, they had a fin in the middle of the back with no bone to support it. The bones of their legs have changed greatly, much more than the plesiosaurs', and often form more than five rows of nearly round or many-sided plates fitted together into a flexible paddle. The tail is like a fish's, but the lower lobe is bigger than the upper, and the backbone bends down into the lower lobe instead of turning up into the upper lobe as it does in fish. The details of the fins are known from some wonderfully preserved specimens found in the fine hardened mud called the lithographic slate of Solenhofen, where the soft bodies of jellyfish and cuttlefish and the wings of flying reptiles are preserved too.

As I mentioned in the first chapter, the Ichthyosauria (see Fig. 2) had a ring of bony plates holding up the eyeball (as birds do too), and these are often preserved in the fossils. Fig. 167 is a view of the top of an Ichthyosaurus skull, to show the round hole in the middle line of the brain case (level with the letter P). It is called the "parietal foramen," and it is a fair-sized hole that held an eye, a third eye called the pineal eye. This eye is found in some other reptiles too, especially in some living lizards, where its structure has been studied under the microscope. There's no doubt that the body filling this hole in living lizards is an eye, though it seems to have lost the power of sight in these modern forms. A third eye on top of the head strikes us as a very strange arrangement, against all our ordinary experience of vertebrate animals.

Fig. 168 is a drawing of the side view of the skeleton of an Ichthyosaurus, with a fossilized lump of its droppings below it. These are called coprolites and are made up of the scales and bones of fishes the Ichthyosaurus digested. They have a corkscrew-like moulding on the surface, which proves that the ichthyosaur's intestine had a spiral fold on its walls, like a spiral staircase, as sharks' intestines have. We also find, inside well-preserved skeletons of Ichthyosaurus, the skeletons of unborn young, showing that the Ichthyosaurus gave birth to live young.

Now we come to even more astonishing reptiles: the extinct order of the pterodactyles, the flying reptiles of the Mesozoic period. These creatures were as truly creatures of the air as the birds and bats of today. There were many kinds, from the size of a crow up to such a huge one as the one drawn in Fig. 169, which measured eighteen feet from one wing tip to the other. Their wings have been found well preserved in the lithographic slates (see Fig. 31), and each was a skin stretched from one enormously long finger to the side of the body and the little hind legs.

Fig. 170 gives some idea of the shape and look of the wings when they were spread. A wing like this is more like a bat's than a bird's, since it is made of skin and not of a row of feathers. The bat's wing is a skin held out by three of the fingers as well as by the side of the body and the hind leg.

In Fig. 171 the fossil wing of a Pterodactyle, a modern bird's wing with only the bones and great quill feathers left in place (the smaller feathers having been plucked out), and a bat's wing are photographed and set together for comparison. There are two other kinds of flying animals: the flying fishes (which don't fly far), and the six-legged insects, the flies, bees and beetles. Each of them has taken up the habit of flying independently and has had certain parts of its body turned into wings. The change must have been gradual, and in each kind it must have taken an enormous stretch of time. Some animals of today, such as the flying squirrels and the flying lizards (Draco volans), don't really fly, since they have no wings to beat the air with. They can spread out a great flat surface on each side of the body, which lets them glide through the air for some distance without falling when they jump from a branch. That, though, is a long way from what animals with wings have achieved, which can strike the air as a fish strikes the water with its fins. The wings of birds and of insects probably both came from fin-like organs used for swimming before they were used in the air. But the wing of the pterodactyles, and separately the wing of the bats, does not seem to have begun that way, and its origin is one of the many very puzzling matters that further discoveries may one day help us understand.

Fig. 172 shows two other kinds of Pterodactyle. Some pterodactyles had no teeth, only long beak-like jaws (Fig. 169). Others had many sharp-pointed teeth and were beasts of prey.

It seems natural to go on from the winged reptiles to the birds. But as a matter of fact birds are not very closely related to pterodactyles. Birds, it seems, come from reptiles; they are highly specialized, warm-blooded descendants of certain reptiles. They are so peculiar that they are counted as a separate "class," and the reptiles nearest to them in structure are the dinosaurs, especially the dinosaurs (like Iguanodon) that walked on their hind legs and had only three toes on the foot. Fossil birds are not plentiful, but a few very interesting ones have been found in the Lower Eocene and in the Cretaceous rocks (see the list of strata in Fig. 41), and one more remarkable than all the rest in the lithographic slates of Jurassic age. Modern birds all have feathers and beaks, and, with one or two rare exceptions, the quill feathers are set on the forearm and hand to form the wing. No living bird has teeth, but fossil birds are known with well-developed teeth like a reptile's. Fig. 173 is a drawing of the skeleton of an extinct bird that had a full set of teeth. The most remarkable extinct bird yet found is the one in Fig. 174. Two specimens of it have come from the lithographic slates of Solenhofen in Bavaria. The first one found is in the Natural History Museum; the second, and more perfect, is in Berlin. This bird, called Archaeopteryx, was the size of a large pigeon, had a short head, apparently without a beak, and its jaws were armed with teeth. Living birds have the fingers of the hand shrunk and bound together, but this bird had three separate fingers, each armed with a claw. Its legs were like those of living birds, and it had four toes. Its tail was unlike that of any living bird, and like a lizard's. The bony part of a living bird's tail is very short and carries the tail feathers fanned out across it, but Archaeopteryx had a long bony tail made of many vertebrae, with the feathers set in a row one behind another on each side of it, so that the tail was shaped like the leaf of a date palm. Strange as this little creature looks, it was a genuine bird, because it had true, well-developed feathers, which show clearly in both fossils. Besides the two rows of feathers on the long tail, there is the full set of feathers spreading from the forearms and hands to form the wings, and the thighs were feathered too.

It can't be said that this ancient extinct bird goes very far towards connecting birds with reptiles. But with its separate clawed fingers, its long bony tail and its teeth, and its apparent lack of a beak, it does come nearer to the lizard-like reptiles than any other bird we know.

Remains of various birds have been found in the Tertiary strata. One of great interest, because of its enormous size, is the Phororachus of South America. Fig. 175 is a photograph of the skull of this bird placed beside the stuffed skin of a living South American bird, the cariama, or screamer. If the extinct bird had the general proportions and habits of the cariama, as seems likely, it must have been a terrible monster, standing some twelve feet high and far beyond the most powerful eagles and vultures in strength and in the size of its beak and claws. Great extinct wingless birds are found in quite recent "alluvial" deposits in New Zealand and in Madagascar. I've already mentioned the discovery of the bones of the great moa of New Zealand in our second chapter. Many species of moa have been found in New Zealand. The moa is related to the ostriches of Africa, the emus and cassowaries of Australia, and the rheas of South America.

It seems that under certain conditions of life birds may gradually lose the use of their wings, which dwindle in size and may finally disappear altogether. Wingless birds of this kind don't necessarily come from one stock. The wingless condition, or a great shrinking of the wings, has come about in various kinds of birds at various periods of the earth's history, and in the same way wingless insects of different orders have come into being. In New Zealand, besides the moas, which are all now extinct, there is a small wingless bird still alive, known as the apteryx, or kiwi. In Fig. 176 we have set one behind another, each with its egg in front of it, a kiwi, the skeleton of a very fine ostrich, and the skeleton of a giant moa (Dinornis maximus). The Polynesian islanders who landed in New Zealand some five hundred years ago found the moas still alive, and hunted them down and lived on their flesh. Skin and feathers of these enormous birds have been found preserved in a dried state as well as their skeletons, and traditions about hunting the moa still survive. The moa of Madagascar seems to have been a smaller bird, but it laid a much larger egg for its size. You'll see in Fig. 176 that the eggs of the ostrich and of the Dinornis are not nearly so big for the size of the bird as the egg of the apteryx, which lays a truly gigantic egg for the size of its body. The moa of Madagascar is known as the Aepyornis, and it laid the biggest egg known, much bigger than that of the biggest New Zealand moa, and like the apteryx in the proportion between its egg and its body. It was this very large egg that fired the imagination of ancient sailors and led to the enormous exaggeration, thrilling the reader with wonder and terror, in Sinbad the Sailor's accounts of the "roc" in the Arabian Nights.

Flightless birds, unless they are great swimmers like the penguins, are bound to be destroyed and become extinct when man arrives. The dodo, which I talked about in my first lecture, was a close relative of the pigeons, but it had lost the power of flight because it had no dangerous enemies on the island of Mauritius. It had become a heavy, slow-running, though powerful ground bird. As soon as man arrived, and the pig with him, the flightless dodo was doomed to extinction. An extinct water bird, the Hesperornis, had no wings at all, while the penguins use their wings for swimming and cannot fly. That was the case too with the gare-fowl, or great auk (Fig. 15), which has lately become extinct.

Chapter Six: Extinct Fishes—Belemnites—Lingula—Trilobites—Scorpions and Stone Lilies

If we had time, we might now look at the remains of the great bony Labyrinthodonts, creatures related to the newts, salamanders and frogs of today, which make up the class Amphibia. They rank below the reptiles, birds and mammals. Though they typically have five toes and crawl or walk on land, they are at heart water animals, since their young are "tadpoles," fishlike in shape and fitted with gills. No reptile, bird or mammal has yet been found in what are called the Palaeozoic strata, but in the Upper Palaeozoic strata, those of the Carboniferous system, the period of the coal-bearing strata (see the table of strata), there was an immense variety of "Amphibia," some of them very large, as large as a full-grown crocodile.

We might call the Carboniferous the age when the Amphibia ruled, as the Jurassic is the age when the reptiles ruled and the Tertiary the age when the mammals rule.

The Labyrinthodonts, though they are of great interest to the trained anatomist, don't offer many striking forms; the most noticeable were the size and shape of large alligators. In the short space we have left, then, I mean to pass over the Labyrinthodonts and go on to the fishes, and show you some of the strange fishes whose remains are dug up in very ancient strata, as far back even as the Upper Silurian and the Devonian rocks. Then I'll have room to mention a few of the more extraordinary extinct animals of the lower kinds: strange shellfish, starfish and scorpions of the remote past.

The silver-scaled fishes that are so plentiful today, with their symmetrical tails, such as the herring, salmon, carp, roach and perch, and other modern fishes of odder shape, such as eels, flatfish, sticklebacks, pipefish and parrotfish, are all of fairly recent origin. They are not found in rocks older than the Cretaceous system. The sharks and dogfish of today, on the other hand, are the most ancient kind of fish we know, for remains of shark-like fishes occur in Silurian strata. But sharks have soft skeletons of cartilage, and as a rule they have left only teeth and spines and the little toothlike scales of the skin (shagreen) in the rocks.

There are, however, certain fishes known that have hard bony scales and often great plates of bone on the head. They are often called "ganoid fishes," from their hard, smooth, bony scales (see Fig. 177), which differ in substance and shape from the thin, flexible scales of ordinary fish. They were very plentiful in Mesozoic and Palaeozoic times and have left their hard scales in very perfect condition in the ancient rocks of those periods. Their tail fins were often triangular and unequally divided, and inside they were built more like the sharks than like modern bony fishes. Very few of these ganoid fishes survive today, but one fine one, the Polypterus (Fig. 178), still lives in the Nile and other African rivers, and another, the bony pike or Lepidosteus, in the North American lakes. The sturgeon belongs to this set of fishes too. In the Devonian, among many others, is found a beautifully preserved fish, the Osteolepis (Fig. 180), which had lobed fins and hard bony scales like the Polypterus of the Nile. Related to these ganoid fishes, but different in having lungs as well as gills and very peculiar lobed fins, are the so-called mudfish of Africa (Protopterus) and of South America (Lepidosiren). A third mudfish lives in the rivers of Queensland, Australia, and is now alive in the Zoological Gardens in London. It is called Ceratodus (Fig. 181), and it is plainly related to some very ancient extinct fishes, the last survivor of their race. One of these ancient forebears of the Ceratodus is found fossil in the Devonian, or Old Red Sandstone, of Scotland and Russia. It is called Dipterus and is shown in Fig. 182. It differs from Ceratodus in having strong bony scales (which is why it was preserved as a fossil) and a triangular tail fin. In the living mudfishes the true tail fin has disappeared altogether. Dipterus has peculiar teeth just like the Ceratodus's, and its fins are of the same character.

In the Devonian strata are also found the extraordinary fishes called Pterichthys. The wonderful Scottish quarryman Hugh Miller, who discovered them seventy years ago and cleaned many specimens out of the rocks of his native hills at Cromarty in Scotland, compared one to a tortoise's shell with a fish stuck into it. From a great many specimens from Canada as well as Scotland we now know in close detail the curious bony plates that build up the case, or "carapace," of the body of Pterichthys (Fig. 183), and also its soft scaly tail and the two extraordinary paddles, or limbs, that stand for the front or breast fins of an ordinary fish. Hugh Miller puzzled this out with great skill and built a cardboard model of the fish, which we still keep in the Natural History Museum. Those of you who have read Hugh Miller's books (The Testimony of the Rocks, My Schools and Schoolmasters and others) will, I think, like to see a photograph of the model of Pterichthys he made with his own hands (Fig. 184).

In the same rocks as Pterichthys there is another very curious fish, the Coccosteus. It and Pterichthys were small, only about a foot long, but in Ohio in the United States the lower jaws and skulls of huge fishes related to Coccosteus have been found, which must have been ten or twelve feet long. The lower jaw of one of these (called Dinichthys), together with a restored outline of Coccosteus, is shown in Fig. 185.

Very strange, curious fishes (only a few inches long) are found in still older strata, in the oldest Devonian and the Upper Silurian. One of them is called the buckler-head, or Cephalaspis (Fig. 186). Its head is shaped like a saddler's knife, with the two eyes near the centre. Another fish is known almost entirely from the shields that covered its head, or its head and body, one above and one below. This is the Pteraspis (Fig. 187). The head shields, or head-and-body shields, of these fishes and of Cephalaspis are found in immense numbers in the hard gritty "cornstones" of Worcestershire and Herefordshire, and in Scotland too. The stone is quarried for road mending, and great quantities of specimens have been found, though no other fossils occur with these fish heads. It used to be thought that this rock was laid down in a great freshwater lake, but that is unlikely, since Pteraspis heads are found with sea shells in the rocks of Galicia. The curious thing is that although a tail or body of Cephalaspis, covered with scales and furnished with fins, has occasionally been found still attached to a head shield, as in Fig. 186, the body or tail of Pteraspis remains unknown. The only specimen showing any trace of the hind part of Pteraspis is one I got as a boy (in 1864) at a quarry in Herefordshire; the workmen I got it from said it was a fossilized fir cone. As a small concession to my vanity, I've had this solitary specimen, which I gave long ago to the Natural History Museum, photographed at its natural size (Fig. 188). It isn't much to look at, but it is one of the most interesting specimens I've ever had the pleasure of unearthing myself. The strange thing is that it is, and remains, unique.

Fig. 189 is a photograph of the upper and lower sides of a model of the Drepanaspis, a very strange fossil fish of the same early age, related to Pteraspis. It was made from the drawings of Professor Traquair, who has described the fish. Crushed specimens of it preserved in the slate of North Germany are in the Natural History Museum.

Fishes of this shape have recently been found in the Silurian strata of Lanarkshire, and they, together with the curious little fishes drawn in Figs. 190 and 191, are the oldest remains of fishes yet found. These last two, Birkenia and Lasanius (Figs. 190, 191), are very puzzling little creatures, with spines set in a row along the belly. It is hard to tell back from belly or to make out eyes or mouth, yet they have unmistakable fish tails and a scaly covering. They are among the most recent discoveries and come from the Upper Silurian strata of Scotland. There are specimens in the Natural History Museum, but the finest series is in the Edinburgh Museum, where Professor Traquair has made a special study of the most ancient fish remains, the most ancient remains of backboned animals yet dug out of the earth's crust.

Ancient, unimaginably ancient, as these Upper Silurian rocks are, there are still immense thicknesses of stratified rock beneath them holding fossils, in which no fish remains have been found. We mustn't conclude that the very curious-looking fishes of the Upper Silurian are really the actual forefathers of all later fishes and of all backboned life. They just happen to have been preserved and dug up. There were probably soft-bodied fishes living then and earlier, with no bones inside and no hard scales outside, which have left no sign of their existence in the rocks. The Upper Silurian strata, as you'll see if you look at the table of strata (Fig. 41), lie just halfway down the thickness of rocks, between the present river gravels above and the Cambrian beds, with the oldest known fossils (certain trilobites), below.

We'll come back to the trilobites in a moment. Before we leave the extinct fishes, though, I want to mention the great fossil sharks of the late Tertiary (Miocene and Pliocene). We know them by their teeth. Enormous sharks' teeth are found, three times the length of the teeth of the biggest living sharks on record, as Fig. 192 shows. They are found beautifully preserved in Malta, in the Antwerp sands, in Maryland, U.S.A., and in Suffolk in England. In Suffolk they occur in the same wonderful bone bed of the Red and Coralline Crag (see Fig. 192a) that gives us the teeth of mastodon, rhinoceros and tapir. It seems a fair conclusion that this huge shark (Carcharodon megalodon) was nearly one hundred feet long, since its teeth were fully three times the length of those of an almost identical living shark (Carcharias rondeletii), which measures thirty feet.

"Extinct animals," as must be obvious at once, include a vast number of smaller creatures besides the backboned fishes, amphibians, reptiles, birds and mammals. There are rocks that hold thousands, even millions, of mollusc shells (whelks, bivalves and so on) crowded together in a space of a few feet. Remains of tiny shrimps are just as plentiful, and whole mountains are built of rock made from the coral, the limy skeleton of tiny polyps like our sea anemones. Many of these are very peculiar forms, unlike any living now. Others, again, are remarkable because although they are found in the most ancient rocks, they closely resemble creatures still alive today.

Now we'll look at a few of the more remarkable "fossils" of these lower, or simpler, kinds. (See the table of classes at the end of Chapter One.)

In the Jurassic strata and in the Greensand and Chalk, wonderful coiled shells are very commonly found, which country people have likened to petrified snakes and to the coiled horns of a ram. These are the so-called ammonites (Fig. 193). There are a great many different kinds, some as big as five feet across. Cut in half, they are seen to be divided inside into a number of chambers. In fact they are built in the same way as the beautiful shells of the pearly nautilus (Fig. 193a), which lives today in the Indian and Pacific oceans. The chambers in the pearly nautilus's shell hold gas and act as a float, while the animal lives in the last chamber (Fig. 194). Only some three or four species of pearly nautilus are alive now, and they stand for a vast variety of extinct creatures that include not only the ammonites but the more ancient goniatites. Some of these extinct relatives of the nautilus, such as Orthoceras, were not coiled at all but quite straight; others were loosely coiled, like the Ancyloceras in Fig. 195; and others were twisted into long spires (Turrilites).

The creature that lived in these shells was like a cuttlefish (as we know from examining the animal of the nautilus), and it belonged to the class Cephalopoda of the great group Mollusca. Besides these, the molluscs include the whelks, snails, mussels, clams and oysters.

A famous fossil that is the internal shell, or "pen," of a kind of cuttlefish is the one known as the belemnite (Fig. 196). In some parts of England, where they are common enough in the clay and shale to catch the eye, these fossils are called "thunderbolts." They are found only in the Jurassic and Cretaceous formations. In fine clay, specimens turn up that show the soft parts of the sort of cuttlefish they grew in (see Fig. 197). They are the same sort of thing as the "cuttlebone" of the living cuttlefish and the pen of the squid (Fig. 198), but more solid and heavy.

The oldest fossils known are found in the Lower Cambrian rocks (see the table of strata, Fig. 41). They are the remains of small sea creatures that were, all the same, by no means very simple in structure. One of them is Lingula davisii (Fig. 199), from the Lingula flags of Wales. Only the simple oval shells are known, but they are almost exactly like the shells of a sea animal that still lives in immense numbers on the shores of the warmer oceans. The living owners of these shells live in great numbers burrowing in sand, and they have a very complex structure and red blood. It is a really remarkable fact that the remote fossil shells of the Lower Cambrian strata should be identical with those of a living animal of high rank in the scale of structure. And that isn't all: we find the shells of Lingula in every deposit above the Cambrian too, so we must conclude that Lingula has lived in the seas of this earth, with very little change of form, ever since Lower Cambrian times.

Another class of fossils just as ancient is the trilobites (Fig. 200). These are well-marked forms with ringed, or jointed, bodies, very often divided lengthwise into three lobes, which is where the old name trilobite comes from. An immense number of different kinds of trilobite are known and classified, but they died out in the Permian period (see the table of strata, Fig. 41). For a long time the legs of these creatures were unknown; they have only been found within the last ten years. Mr. Beecher, of the United States, found them in one particular kind, Triarthrus becki (Fig. 201). Some people think these animals were related to the woodlice or other shrimp-like crustaceans living now. But it seems most likely that they were a primitive sea-living group related to the scorpions, spiders and king crabs (the Arachnida).

It is a fact of very great significance that the earliest fossils yet found are the remains of very highly developed animals, nowhere near the beginning of animal life. It is a reasonable supposition, indeed, that the earliest forms of animal life must have come before the Cambrian trilobites and Lingula by as long a time as these come before the animals living today. Apparently the soft-bodied animals that came before the Cambrian fossils have left no remains in the rocks beneath the Cambrian, or else their remains have been destroyed by chemical and structural changes in those most ancient deposits.

The scorpion itself (Fig. 202) is a very ancient and important animal, which struck the imagination of even the earliest civilized people so strongly that they named one of the constellations after it. Some hundreds of distinct species of scorpion are known to be living today in various parts of the world. In the Carboniferous strata we find fossil scorpions hardly different at all from those alive now, and even in the Upper Silurian we find a scorpion (Fig. 203) that a child would recognize at once as a true scorpion. It seems likely, though, that while modern scorpions live on land and breathe air through lung sacs, the Silurian scorpion lived in water. Its thick, crablike legs with strong pointed end joints suggest it (Figs. 204 and 205).

Besides the Silurian scorpion, so plainly related to modern scorpions, we find in the Silurian and Devonian rocks the remains of enormous water-living scorpion-like creatures, sometimes four or five feet long (Figs. 207, 208, 209). These are known as the eurypterids (Pterygotus, Stylonurus, Eurypterus and others). They had six legs, like the scorpion, and in some of them the front pair carried pincers. The great spine at the end of the body stands for the scorpion's sting, and they agree with scorpions in the position and character of the eyes and in the number of segments, or rings, that build up the body and head.

A very interesting animal that is still alive (though it is also found in ancient rocks) links the scorpions with the great extinct eurypterids and with the trilobites too. This is the king crab (Figs. 210, 211, 212). It is not a true crab, that is, a member of the class Crustacea, but a sort of sea scorpion with a shortened tail (though it has a long sting-like spine at the end of its body), a member of the class Arachnida. Its legs, six in number (Fig. 212), are remarkably like the scorpion's, and in a great many small details it agrees with the scorpions (see Fig. 213) and differs from crabs. It is the only surviving representative of the water-living ancestors from which the modern air-breathing scorpions and spiders have developed.

From among all the great variety of extinct invertebrate animals, I've chosen for our last pictures and descriptions a few of the beautiful stone lilies, or Pentacrini, or encrinites, as they used to be called. They have a very interesting history, because they were known as fossils as long ago as the seventeenth century, many years before anyone found them alive. They are a kind of starfish, with long delicate arms attached to a central cup, or body, mounted on a jointed stalk that is often very long. Several kinds are shown in Figs. 214, 215 and 216. The fossil remains we find are the hard internal skeleton, made of carbonate of lime, which was a very prominent feature of their structure. It is the same kind of thing as the hard boxlike skeleton of the sea urchins, which, with the starfish, make up the great group naturalists call the Echinoderma.

In the eighteenth century a living encrinite, or stalked starfish, was found in deep water off Martinique in the West Indies, brought dried to Europe, and described as a "sea palm tree." For a long time such specimens were very rare and hard to come by, but now a great many have been dredged up from deep water in different parts of the world. Even so, only a dozen or so different kinds, or species, of encrinite are still alive, whereas in all the older rocks we find their remains, often in great profusion. Many hundreds of extinct kinds are known, and they go back as far as the Cambrian rocks and are wonderfully varied and plentiful in the Silurian, Devonian and Carboniferous (Fig. 215). Some of the finest come from the Jurassic strata (Figs. 214 and 216).

A very interesting discovery about the encrinites was made in 1836 by a famous English naturalist, Vaughan Thompson. He was an army surgeon stationed at Cork, where he studied the sea animals of Queenstown harbour. He found out many new and important things by watching under the microscope how barnacles, starfish and sea moss grow from the egg, keeping them alive in small glass vessels.

First of all, Vaughan Thompson discovered in the sea at Queenstown a tiny encrinite, not a third of an inch long (Fig. 217), and he named it Pentacrinus europaeus. The only other living encrinite known at the time was the large one from the West Indies, which was called Pentacrinus asteria.

That was astonishing enough, but there was more to come. Next, Vaughan Thompson found that the body of his little Pentacrinus europaeus grows bigger and bigger while the stalk shrivels and stops growing, so that the animal breaks loose and swims away freely by moving its arms. It grows up into a well-known starfish, the feather star, or comatula (Fig. 218). At first nobody believed this story, and the Royal Society of London refused to publish Vaughan Thompson's account of what he had seen. But it was soon fully established. Many observers bred the little Pentacrini in glass jars from the eggs of the feather star, and all of them were seen, after a certain time, to go on to become free-swimming little starfish. That proved what the structure of its feathered arms and other parts makes clear enough anyway: the feather star, or comatula, is unlike other starfish, and is a Pentacrinus (or stone lily, or encrinite, or crinoid) that has lost its stalk. And all the while the naturalists of 250 years ago were arguing over what the stone lilies in the rocks really were, little stone lilies a quarter of an inch long were being produced in plenty every year close at hand, in the sea along the rocky shores of England and France and in the Mediterranean. The first living, unfossilized Pentacrinus naturalists saw was brought all the way from Martinique, while any number of tiny ones could have been found living on our own shores. These European Pentacrini went unnoticed because they are so small, and because the stalk shrinks and is lost so suddenly. Only in its very young stage does the common feather star of today keep the most remarkable feature of its remote Cambrian ancestors, the stalk. But for a brief week or so, while it is almost invisible to the naked eye, it does have a well-grown stalk, by which it is fixed just as its remote forefathers were fixed by their splendid waving stems, many feet long.

In these pages I've only been able to show the reader a few of the marvellous and delightful things we know as "fossils," a very small selection of what is known about extinct animals. I have avoided going into much detail and using more technical terms and long names than were absolutely necessary. You can't talk about these things without naming them; and though it's true that a fossil "called by any other name" would be just as interesting, we must have a definite name to call each kind of animal and each kind of rock by. Once your interest in these astoundingly ancient and curious remains of extinct creatures is aroused, it really isn't very difficult to remember their names and tell them apart, and to recognize them when you meet the names in books or museums. To learn more than the few facts I've stated so briefly in these pages, the reader should visit the Natural History Museum many times, look at the actual specimens, and get to know more about them with the help of the illustrated guidebooks. And if he or she has the chance to go hunting in some of the quarries or cliffs that are so often full of fossils, an endless delight and a healthy pursuit lie ahead. Fossil hunting, with hammer and chisel and a bag to fill with specimens, is splendid exercise, and if it is done skilfully, an exciting form of sport. Even within a Londoner's day out there are the brick-fields of Ilford and Grays, where I used to find remains of mammoth, rhinoceros and such beasts; the chalk and Tertiary strata of Charlton in Kent, full of fossils; the Red Crag pits of Suffolk; the oolites of Oxford; the sponge gravel of Faringdon. A very little further brings the fossil hunter to the Isle of Wight, which used to be, and I don't doubt still is, a magnificent preserve of Eocene, Greensand and Wealden fossils; and no further off in time are the Malvern hills, with Silurian and Devonian strata laid open in quarries and railway cuttings, teeming with fossils. And there is always the chance, a good sportsman's chance, of finding "something new," if you know your business and never tire of digging in sand and clay, hammering the rock, and looking up quarrymen and those delightful people, rarer now than they were forty years ago, the local naturalists. I hope that many, if not all, of my readers will be stirred by the accounts and pictures of extinct animals I've given in these pages to become "soldiers of the hammer," as Sir Roderick Murchison used to call us, and collectors of fossils, and, if good fortune smiles on them, discoverers of things as yet unknown to man.