The Tertiary Age, and Its Characteristic Animals

IN entering upon the Tertiaries, we reach that geological age which, next to his own, has the deepest interest for man. The more striking scenes of animal life, hitherto confined chiefly to the ocean, are now on land; the extensive sheets of fresh water are filled with fishes of a comparatively modern character, — with White-fish, Pickerel, Perch, Eels, etc., — while the larger quadrupeds are introduced upon the continents so gradually prepared to receive them. The connection of events throughout the Tertiaries, considered as leading up to the coming of man, may be traced not only in the physical condition of the earth, and in the presence of the large terrestrial Mammalia, but also in the appearance of those groups of animals and plants which we naturally associate with the domestic and social existence of man. Cattle and Horses are first found in the middle Tertiaries; the grains, the Rosaceæ, with their variety of fruits, the tropical fruit-trees, Oranges, Bananas, etc., the shadeand cluster-trees, so important to the comfort and shelter of man, are added to the vegetable world during these epochs. The fossil vegetation of the Tertiaries is, indeed, most interesting from this point of view, showing the gradual maturing and completion of those conditions most intimately associated with human life. The earth had already its seasons, its spring and summer, its autumn and winter, its seed-time and harvest, though neither sower nor reaper was there ; the forests then, as now, dropped their thick carpet of leaves Upon the ground in the autumn, and in many localities they remain where they originally fell, with a layer of soil between the successive layers of leaves, — a leafy chronology, as it were, by which we read the passage of the years which divided these deposits from each other. Where the leaves have fallen singly on a clayey soil favorable for receiving such impressions, they have daguerreotyped themselves with the most wonderful accuracy, and the Oaks, Poplars, Willows, Maples, Walnuts, Gumand Cinnamon-trees, etc., of the Tertiaries are as well known to us as are those of our own time.

It was an eventful day, not only for science, but for the world, when a Siberian fisherman chanced to observe a singular mound lying near the mouth of the River Lena, where it empties into the Arctic Ocean. During the warmer summer-weather, he noticed, that, as the snow gradually melted, this mound assumed a more distinct and prominent outline, and at length, on one side of it, where the heat of the sun was greatest, a dark body became exposed, which, when completely uncovered, proved to be that of an immense elephant, in so perfect a state of preservation that the dogs and wolves were attracted to it as by the smell of fresh meat, and came to feed upon it at night. The man knew little of the value of his discovery, but the story went abroad, and an Englishman travelling in Russia, being curious to verify it, visited the spot, and actually found the remains where they had been reported to lie, on the frozen shore of the Arctic Sea, — strange burial-place enough for an animal never known to exist out of tropical climates. Little beside the skeleton was left, though parts of the skin remained covered with hair, showing how perfect must have been the condition of the body when first exposed. The tusks had been sold by the fisherman; but Mr. Adams succeeded in recovering them; and collecting all the bones, except those of one foot, which had been carried off by the wolves, he had them removed to St. Petersburg, where the skeleton now stands in the Imperial Museum. The inhabitants of Siberia seem to be familiar with this animal, which they designate by the name of Mammoth, while naturalists call it Elephas primigenius. The circumstance that they abound in the frozen drift of the great northern plain of Asia, and are occasionally exposed in consequence of the wearing of the large rivers traversing Siberia, has led to the super stition among the Tongouses, that the Mammoths live under ground, and die whenever, on coming to the surface, the sunlight falls upon them.

Had this been the only creature of the kind found so far from the countries to which elephants are now exclusively confined, it might have been believed that some strange accident had brought it to the spot where it was buried. But it was not long before similar remains were found in various parts of Europe,—in Russia, in Germany, in Spain, and in Italy. The latter were readily accounted for by the theory that they must be the remains of the Carthaginian elephants brought over by the armies of Hannibal, while it was suggested that the others might have been swept from India by some great flood, and stranded where they were found. It was Cuvier, entitled by his intimate acquaintance with the anatomy of living animals to an authoritative opinion in such matters, who first dared to assert that these remains belonged to no elephant of our period. He rested this belief upon structural evidence, and insisted that an Indian elephant, brought upon the waves of a flood to Siberia, would be an Indian elephant still, while all these remains differed in structure from any species existing at present. This statement aroused research in every direction, and the number of fossil Mammalia found within the next few years, and proved by comparison to be different from any living species, soon demonstrated the truth of his conclusion.

Shortly after the discovery of fossil elephants had opened this new path of investigation, some curious bones were found by some workmen in the quarries of Montmartre, near Paris, and brought to Cuvier for examination. Although few in number, and affording but very scanty data for such a decision, he at once pronounced them to be the remains of some extinct animal preceding the present geological age. Here, then, at his very door, as it were, was a settlement of that old creation in which he could pursue the inquiry, already become so important in its bearings. It was not long before other bones of the same kind were found, though nothing as yet approaching an entire skeleton. However, with such means as he had, Cuvier began a comparison with all the living Mammalia, — with the human skeleton first, with Monkeys, with the larger Carnivora and Ruminants, then with all the smaller Mammalia, then with the Pachyderms; and here, for the first time, he began to find some resemblance. He satisfied himself that the animal must have belonged to the family of Pachyderms ; and he then proceeded to analyze and compare all the living species, till he had collected ample evidence to show that the bones in question did not correspond with any species, and could not even be referred to any genus, now in existence. At length there was discovered at Montmartre an upper jaw of the same animal,— next a lower jaw, matching the upper one, and presently a whole head with a few backbones was brought to light. These were enough, with Cuvier’s vast knowledge of animal structure, to give him a key to the whole skeleton. At about the same time, in the same locality, were found other bones and teeth also, differing from those first discovered, and yet equally unlike those of any living animal. The first evidently belonged to some stout and heavy animal, the others were more slender and of lighter build. From these fragments, ample evidence to him of his results, he drew the outlines of two animals : one which he called the Palæotherium, (old animal,) a figure of which is given in the above woodcut, and the other Anoplotherium, (animal without fangs). He presented these figures with an explanatory memoir at the Academy, and announced them as belonging to some creation preceding the present, since no such animals had ever existed in our own geological period. Such a statement was a revelation to the scientific world: some looked upon it with suspicion and distrust; others, who knew more of comparative anatomy, hailed it as introducing a new era in science; but it was not till complete specimens were actually found of animals corresponding perfectly to those figured and described by Cuvier, and proving beyond a doubt their actual existence in ancient times, that all united in wonder and admiration at the result obtained by him with such scanty means.

It would seem that the family of Pachyderms was largely represented among the early Mammalia; for, since Cuvier named these species, a number of closely allied forms have been found in deposits belonging to the same epoch. Of course, the complete specimens are rare ; but the fragments of such skeletons occur in abundance, showing that these oldworld Pachyderms, resembling the Tapirs more than any other living representatives of the family, were very numerous in the lower Tertiaries.

There is, however, one animal now in existence, forming one of those singular links before alluded to between the present and the past, of which I will say a few words here, though its relation is rather with a later group of Tertiary Pachyderms than with those described by Cuvier. On the coast of Florida there is an animal of very massive, clumsy build, long considered to be a Cetacean, but now recognized, by some naturalists at least, as belonging to the order of Pachyderms. In form it resembles the Cetaceans, though it has a fanshaped tail, instead of the broad flapper of the Whales. It inhabits fresh waters or shoal waters, and is not so exclusively aquatic as the oceanic Cetaceans. Its most striking feature is the form of the lower jaw, which is bent downward, with the front teeth hanging from it. This animal is called the Manatee, or SeaCow. There are three species known to naturalists, — one in Tampa Bay, one in the Amazon, and one in Africa. In the Tertiary deposits of Germany there has been found an animal allied in some of its features to those described by Cuvier, but it has the crown of its teeth folded like the Tapir, while the lower jaw is turned down with a long tusk growing from it. This animal has been called the Dinotherium. A part of the head, showing the heavy jaws and the formidable tusk, is represented in the subjoined wood-cut. Its hanging lower jaw, with the protruding tusk, corresponds perfectly to the formation of the lower jaw and teeth in the Manatee. Some resemblance of the Dinotherium to the Mastodon suggested a comparison with that animal as the next step in the investigation, when it was found that at the edge of the lower jaw of the latter there was a pit with a small projecting tooth, also corresponding exactly in its position to the tusk in the Dinotherium. The Elephant was now examined; and in him also a rudimentary tooth appeared in the lower jaw, not cut through, but placed in the same relation to the jaw and the other teeth as that of the Mastodon. It would seem, then, that the Manatee makes one in this series of Dinotherium, Mastodon, and Elephant, and represents the aquatic Pachyderms, occupying the same relation to the terrestrial Pachyderms as the Seals bear to the terrestrial Carnivora, and, like them, lowest in structure among their kind.

The announcement of Cuvier’s results stimulated research, and from this time forward Tertiary Mammalia became the subject of extensive and most important investigations among naturalists. The attention of collectors once drawn to these remains, they were found in such numbers that the wonder was how they had been so long hidden from the observation of men. They remind us chiefly of tropical animals; indeed, Tigers, Hyenas, Rhinoceroses, Hippopotamuses, Mastodons, and Elephants had their home in countries which now belong to the Cold Temperate Zone, showing that the climate in these latitudes was much milder then than it is at present. Bones of many of these animals were found in caverns in Germany, France, Italy, and England. Perhaps the story of Kirkdale Cave, where the first important discovery of this kind was made on English soil, may not be so well known to American readers as to forbid its repetition here.

It was in the summer of 1821 that some workmen, employed in quarrying stone upon the slope of a limestone hill at Kirkdale, in Yorkshire, came accidentally upon the mouth of a cavern. Overgrown with grass and bushes, the mouth of this cave in the hill-side had been effectually closed against all intruders, and it was not strange that its existence had never been suspected. The hole was small, but large enough to admit a man on his hands and knees ; and the workmen, creeping in through the opening, found that it led into a cavern, broad in some parts, but low throughout. There were only a few spots where a man could stand upright; but it was quite extensive, with branches opening out from it, some of which have not yet been explored. The whole floor was strewn, from one end to the other, with hundreds of bones, like a huge dog-kennel. The workmen wondered a little at their discovery, but, remembering that there had been a murrain among the cattle in this region some years before, they came to the conclusion that these must be the bones of cattle that had died in great numbers at that time; and, having so settled the matter to their own satisfaction, they took little heed to the bones, but threw many of them out on the road with the common limestone. Fortunately, a gentleman, living in the neighborhood, whose attention had been attracted to them, preserved them from destruction ; and a few months after the discovery of the cave, Dr. Buckland, the great English geologist, visited Kirkdale, to examine its strange contents, which proved indeed stranger than any one had imagined; for many of these remains belonged to animals never before found in England. The bones of Hyenas, Tigers, Elephants, Rhinoceroses, and Hippopotamuses were mingled with those of Deer, Bears, Wolves, Foxes, and many smaller creatures. The bones were, gnawed, and many were broken, evidently not by natural decay, but seemed to have been snapped violently apart. After the most complete investigation of the circumstances, Dr. Buckland convinced himself, and proved to the satisfaction of all scientific men, that the cave had been a den of Hyenas1 at a time when they, as well as Tigers, Elephants, Rhinoceroses, etc., existed in England in as great numbers as they now do in the wildest parts of tropical Asia or Africa. The narrow entrance to the cave still retained the marks of grease and hair, such as one may see on the bars of a cage in a menagerie against which the imprisoned animals have been in the habit of rubbing themselves constantly, and there were marks of the same kind on the floor and walls. It was evident that the Hyenas were the lords of this ancient Cavern, and the other animals their unwilling guests; for the remains of the latter were those which had been most gnawed, broken, and mangled ; and the head of an enormous Hyena, with gigantic fangs found complete, bore ample evidence to their great size and power. Some of the animals, such as the Elephants, Rhinoceroses, etc., could not have been brought into the cave without being first killed and torn to pieces, for it is not large enough to admit them. But their gnawed and broken bones attest, nevertheless, that they were devoured like the rest; and probably the Hyenas then had the same propensity which characterizes those of our own time, to tear in pieces the body of any dead animal, and carry it to their den to feed upon it apart.

While Kirkdale Cave was evidently the haunt of Hyenas chiefly, other caverns in Germany and France were tenanted in a similar manner by a gigantic species of Bear. Their remains, mingled with those of the animals on which they fed, have been found in great numbers in the Cavern of Gailenreuth, in Franconia. The subjoined wood-cut shows the head of this formidable beast, which must have exceeded in size any Bear now living. Indeed, although there were many smaller kinds, and the other types of the Animal Kingdom in the Tertiaries seem to approach very nearly both in size and general character their modern representatives, yet, on the whole, the earlier Mammalia were giants in comparison with those now living. The Mastodon and Mammoth, as compared with the modern Elephant, the Megatherium, as compared with the Sloths of present times, the Hyenas and Bears of the European caverns, and the fossil Elk of Ireland, by the side of which even the Moose of our Northern woods is belittled, are remarkable instances in proof of this. One cannot but be struck with the fact that this first representation of Mammalia, the very impersonation of brute force in power, size, and ferocity, immediately preceded the introduction of man, with whose creation intelligence and moral strength became the dominant influences on earth.

Among these huge Tertiary Mammalia, one of those most common on the North-American continent seems to have been the Mastodon. The magnificent specimens preserved in this country are too well known to require description. The remains of the Rhinoceros occur also in the recent Tertiary deposits of North America, though as yet no perfect skeletons have been found. The Edentata, now confined to South America and the western coast of Africa, were also numerous in the Southern States during that time; their remains have been found as far north as the Salt Lick in Kentucky. But we must not judge of the Tertiary Edentata by any now known to us. The Sloths, the Armadillos, the Ant-Eaters, the Pangolins, are all animals of rather small size; but formerly they were represented by the gigantic Megatherium, the Megalonyx, and the Mylodon, some of which were larger than the Elephant, and others about the size of the Rhinoceros or Hippopotamus. The subjoined woodcut represents a Mylodon in the act of lifting himself against the trunk of a tree. They were clumsy brutes, and though their limbs were evidently built with reference to powerful movements, perhaps climbing, or at least rising on their hind quarters, the act of climbing with them cannot have had anything of the nimbleness or activity generally associated with it. On the contrary, they probably were barely able to support their huge bodies on the hind limbs, which are exceedingly massive, and on the stiff, heavy tail, while they dragged down with their front limbs the branches of the trees, and fed upon them at leisure. The Zoölogical Museum at Cambridge is indebted to the generosity of Mr. Joshua Bates for a very fine set of casts taken from the Megatherium in the British Museum. They are now mounted, and may be seen in one of the exhibition-rooms of the building. Large Reptiles, but very unlike those of the Cretaceous and Jurassic epochs, belonging chiefly to the types of Turtles, Crocodiles, Pythons, and Salamanders, existed during the Tertiary epochs. The wood-cut below represents a gigantic Salamander of the Tertiary deposits. It is a curious fact, illustrative of the ignorance of all anatomical science in those days, that, when the remains of this reptile (Audrias, as it is now called) were first discovered toward the close of the seventeenth century, they were described by old Professor Scheuchzer as the bones of an infant destroyed by the Deluge, and were actually preserved, not for their scientific value, but as precious relics of the Flood, and described in a separate pamphlet, entitled, “ Homo Diluvii Testis.” Among the Tertiary Reptiles the Turtles seem to have been a very prominent type, by their size as well as by their extensive distribution. Their remains have been found both in the far West and in the East. The fossil Turtles of Nebraska are well known to American naturalists; but the Oriental one exceeds them in size, and is, indeed, the most gigantic representative of the order known thus far. A man could stand under the arch of the shield of the old Himalayan Turtle preserved in the British Museum.

It would carry me too far, were I to attempt to give anything more than the most cursory sketch of the animals of the Tertiary age ; and, indeed, they are so well known, and have been so fully represented in text-books, that I fear some of my readers may think even now that I have dwelt too long upon them. Monkeys were unquestionably introduced upon earth before the close of the Tertiaries; some bones have been found in Southern France, and also on Mount Pentelicus in Greece, in the later Tertiary deposits ; but these remains have not yet been collected in sufficient number to establish much more than the fact of their presence in the animal creation at that time. I do not offer any opinion respecting the fossil human bones so much discussed recently, because the evidence is at present too scanty to admit of any decisive judgment concerning them. It becomes, however, daily more probable that facts will force us sooner or later to admit that the creation of man lies far beyond any period yet assigned to it, and that a succession of human races, as of animals, have followed one another upon the earth. It may be the inestimable privilege of our young naturalists to solve this great problem, but the older men of our generation must be content to renounce this hope ; we may have some prophetic vision of its fulfilment, we may look from afar into the land of promise, but we shall not enter in and possess it.

The other great types of the Animal Kingdom are very fully represented in the Tertiaries, and in their general appearance they approach much more closely those of the present creation than of any previous epochs. Professor Heer has collected and described the Tertiary Insects in great number and variety; and the Butterflies, Bugs, Flies, Grasshoppers, Dragon-Flies, Beetles, etc., described in his volumes, would hardly be distinguished from our own, except by a practised entomologist. Among Crustacea, the Shrimp-like forms of the earlier geological epochs have become much less conspicuous, while Crabs and Lobsters are now the prominent representatives of the class. Among Mollusks, the Chambered Shells, hitherto so numerous, have become, as they now are, very few in comparison with the naked Cephalopods. The Nautili, however, resemble those now living in the Pacific Ocean ; and some fragments of the Paper-Nautilus have been found, showing that this delicate shell was already in existence. There is one very peculiar type of this class, belonging to the Tertiaries, which should not be passed by unnoticed. It partakes of the character both of the Cretaceous Belemnites and of the living Cuttle-Fish, and is known as the Spirulirostra. Another very characteristic group among the Tertiary Shells is that of the Nummulites, formerly placed by naturalists in immediate proximity with the Ammonites, on account of their internal partitions. This is now admitted to have been an error ; their position is not yet fully determined, but they certainly stand very low in the scale, and have no affinity whatever with the Cephalopods. The subjoined wood-cut represents one of these Shells, so numerous in the Tertiaries that large masses of rock consist of their remains. The Univalve Shells or Gasteropods of the Tertiaries embraced all the families now living, including land and fresh-water Shells as well as the marine representatives of the type. Some of the latter, as, for instance, the Cerithium, are accumulated in vast numbers. The limestone quarries out of which Paris is chiefly built consist wholly of these Shells. The fresh-water basins were filled with Helices, one of which is represented in the following wood-cut, with Planorbis, Limnæus, and other Shells resembling those now so common in all our lakes and rivers, and differing from the living ones only by slight specific characters. The Bivalves also have the same resemblance to the present ones, including fresh-water Mussels as well as the marine Clams and Oysters. Among Radiates, the higher Echini (Sea-Urchins) have become numerous, while the other Echinoderms of all families abound. Corals include, for the first time, the more highly organized Madrepores.

In the Tertiaries we see the dawn of the present condition of things, not only in the character of the animals and plants, but in the height of the mountains and in the distribution of land and sea.

Let us give a glance at the continents whose growth we have been following, and see what these more recent geological epochs have done for their completion. In Europe they have filled the basin in Central France, and converted all that region into dry land; they have filled also the channel between France and Spain ; they have united Central Russia with the rest of Europe by the completion of Poland, and have greatly enlarged Austria and Turkey ; they have completed the promontories of Italy and Greece, and have converted the inland sea at the foot of the Jura into the plain of Switzerland. But this fruitful period in the progress of the world, when the character of organic life was higher and the physical features of the earth more varied than ever before, was not without its storms and convulsions. The Pyrenees, the Apennines, the Alps, and with them the whole range of the Caucasus and Himalayas, were raised either immediately after the Cretaceous epoch, or in the course of the Tertiaries. Indeed, with this most significant passage in her history, Europe acquired all her essential characters. There remained, it is true, much to be done in what is called by geologists “ modern times.” The work of the artist is not yet finished when his statue is blocked out and the grand outline of his conception stands complete; and there still remained, after the earth was rescued from the water, after her framework of mountains was erected, after her soil was clothed with field and forest, processes by which her valleys were to be made more fruitful, her gulfs to be filled with the rich detritus poured into them by the rivers, her whole surface to be rendered more habitable for the higher races who were to possess it.

We left America at the close of the Carboniferous epoch. A glance at the geological map will show the reader that during the Permian, Triassic, and Jurassic epochs little was added to the United States, though here and there deposits belonging to each of them crop out. In the Cretaceous epoch, however, large tracts of land were accumulated, chiefly in the South and West; and during the Tertiaries the continent was very nearly completed, leaving only a narrow gulf running up to the neighborhood of St. Louis to be filled by modern detritus, and the peninsula of Florida to be built by the industrious Coral-Workers of our own period. The age of the Alleghany chain is not yet positively determined, but it was probably raised at the close of the Carboniferous epoch. Up to that time, only the Laurentian Hills, the northern side of that mountainous triangle which now makes the skeleton, as it were, of the United States, existed. The upheaval of the Alleghanies added its eastern side, raising the central part of the continent so as to form a long slope from the base of the Alleghanies to the Pacific Ocean ; but it was not until the Tertiary Age that the upheaval of the great chain at the West completed the triangle, and transformed that wide westerly slope into the Mississippi Valley, bounded on one side by the Alleghanies, and on the other by the Rocky Mountains.

It is my belief, founded upon the tropical character of the Fauna, that a much milder climate then prevailed over the whole northern hemisphere than is now known to it. Some naturalists have supposed that the presence of the tropical Mammalia in the Northern Temperate Zone might be otherwise accounted for, — that they might have been endowed with warmer covering, with thicker hair or fur. But I think the simpler and more natural reason for their existence throughout the North is to be found in the difference of climate ; and I am the more inclined to this opinion because the Tertiary animals generally, the Fishes, Shells, etc., in the same regions, are more closely allied in character to those now living in the Tropics than to those of the Temperate Zones. The Tertiary age may be called the geological summer; we shall see, hereafter, how abruptly it was brought to a close.

One word more as to the relation of the Tertiary Mammalia to the creation which preceded them. I can only repeat here the argument used before: the huge quadrupeds characteristic of these epochs make their appearance suddenly, and the deposits containing them follow as immediately upon those of the Cretaceous epoch, in which no trace of them occurs, as do those of the Cretaceous upon those of the Jurassic epoch. I would remind the reader that in the central basin of France, in which Cuvier found his first Palæotherium, and which afterwards proved to have been thickly settled by the early Mammalia, the deposits of the Jurassic, Cretaceous, and Tertiary epochs follow each other in immediate, direct, uninterrupted succession; that the same is true of other localities, in Germany, in Southern Europe, in England, where the most complete collections have been made from all these deposits ; and there has never been brought to light a single fact leading us to suppose that any intermediate forms have ever existed through which more recent types have been developed out of older ones. For thirty years Geology has been gradually establishing, by evidence the fulness and accuracy of which are truly amazing, the regularity in the sequence of the geological formations, and distinguishing, with ever-increasing precision, the specific differences of the animals and plants contained in these accumulations of past ages. These results bear living testimony to the wonderful progress of the kindred sciences of Geology and Palæontology in the last half-century; and the development-theory has but an insecure foundation so long as it attempts to strengthen itself by belittling the geological record, the assumed imperfection of which, in default of positive facts, has now become the favorite argument of its upholders.

  1. Among the other facts showing that Kirkdale Cave had been the den of these animals, and not tenanted as their home by any of the other creatures whose remains occurred there, were the excrements of tlie Hyenas found in considerable quantity by Dr. Buckland, and identified as such by the keeper of a menagerie. Any one who may wish to read the whole history of Dr. Buckland's investigations of this matter, showing the patience and sagacity with which he collected and arranged the evidence, will find a full account of Kirkdale Cave and other caverns containing fossil bones in his “ Reliquiæ Diluviaæ,”