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 Whitefish, 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
shade- and 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, Gum- and
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 superstition among the Tongouses, that the
Mammoths live under ground, and die whenever, on coming to the surface,
the sunlight falls upon them.
[Illustration]
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.
[Illustration]
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
wood-cut, 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
old-world 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 fan-shaped 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 Sea-Cow. 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.
[Illustration]
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 Hyenas[A] 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.
[Footnote A: 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 the
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 Diluvianæ."]
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.
[Illustration]
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.
[Illustration]
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 same size of the Rhinoceros or Hippopotamus. The
subjoined wood-cut represents a Mylodon in the act of lifting himself
against the trunk of a tree.
[Illustration]
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 their 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.
[Illustration]
[Illustration]
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.
[Illustration]
[Illustration]
[Illustration]
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.
[Illustration]
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.