The Miocene formation is not present in England; unless we suppose, with
Sir Charles Lyell, that it is represented by the Hempstead beds of the
Isle of Wight.
It is on the European continent that we find the most striking
characteristics of the Miocene period. In our own islands traces of it
are few and far between. In the Island of Mull certain beds of shale,
interstratified with basalt and volcanic ash, are described by the Duke
of Argyll as of Miocene date;[90] and Miocene clay is found
interstratified with bands of imperfect coal at Bovey Tracey. The
vegetation which distinguished the period is a mixture of the vegetable
forms peculiar to the burning climate of the present tropical Africa,
with such as now grow in temperate Europe, such as Palms, Bamboos,
various kinds of Laurels, Combretaceæ (Terminalia), with the grand
Leguminales of warm countries (as _Phaseolites_, _Erythrina_,
_Bauhinia_, _Mimosites_, _Acacia_); Apocyneæ analogous to the genera of
our tropical regions; a _Rubiacea_ altogether tropical (_Steinhauera_)
mingle with some Maples, Walnut-trees, Beeches, Elms, Oaks, and
Wych-elms, genera now confined to temperate and even cold countries.
[90] _Quarterly Journal of Geol. Soc._, vol. vii., p. 89.
Besides these, there were, during the Miocene period, mosses, mushrooms,
charas, fig-trees, plane-trees, poplars, and evergreens. “During the
second period of the Tertiary epoch,” says Lecoq, “the Algæ and marine
Monocotyledons were less abundant than in the preceding age; the Ferns
also diminished, the mass of Conifers were reduced, and the Palms
multiplied in species. Some of those cited in the preceding period seem
still to belong to this, and the magnificent _Flabellaria_, with the
fine _Phœnicites_, which we see now for the first time, gave animation
to the landscape. Among the Conifers some new genera appear; among them
we distinguish _Podocarpens_, a southern form of vegetation of the
present age. Almost all the arborescent families have their
representatives in the forests of this period, where for the first time
types so different are united. The waters are covered with _Nymphæa
Arithnæa_ (Brongniart); and with _Myriophyllites capillifolius_ (Unger);
_Culmites animalis_ (Brongniart); and _C. Gœpperti_ (Munster), spring up
in profusion upon their banks, and the grand _Bambusinites sepultana_
throws the shadow of its long articulated stem across them. Some
analogous species occupy the banks of the great rivers of the New World;
one Umbellifera is even indicated, by Unger, in the _Pimpinellites
zizioides_.
Of this period date some beds of lignite resulting from the
accumulation, for ages, of all these different trees. It seems that
arborescent vegetation had then attained its apogee. Some _Smilacites_
interlaced like the wild vines with these grand plants, which fell on
the ground where they grew, from decay; some parts of the earth, even
now, exhibit these grand scenes of vegetation. They have been described
by travellers who have traversed the tropical regions, where Nature
often displays the utmost luxury, under the screen of clouds which does
not allow the rays of the sun to reach the earth. M. D’Orbigny cites an
interesting instance which is much to the point. “I have reached a
zone,” he says (speaking of Rio Chapura in South America), “where it
rains regularly all the year round. We can scarcely perceive the rays of
the sun, at intervals, through the screen of clouds which almost
constantly veils it. This circumstance, added to the heat, gives an
extraordinary development to the vegetation. The wild vines fall on all
sides, in garlands, from the loftiest branches of trees whose summits
are lost in the clouds.”
The fossil species of this period, to the number of 133, begin to
resemble those which enrich our landscapes. Already tropical plants are
associated with the vegetables of temperate climates; but they are not
yet the same as existing species. Oaks grow side by side with Palms, the
Birch with Bamboos, Elms with Laurels, the Maples are united to the
Combretaceæ, to the Leguminales, and to the tropical Rubiaceæ. The forms
of the species, belonging to temperate climates, are rather American
than European.
The luxuriance and diversity of the Miocene flora has been employed by a
German savant in identifying and classifying the Middle Tertiary or
Miocene strata of Switzerland. We are indebted to Professor Heer, of
Zurich, for the restoration of more than 900 species of plants, which he
classified and illustrated in his “Flora Tertiaria Helvetiæ.” In order
to appreciate the value of the learned Professor’s undertaking, it is
only necessary to remark that, where Cuvier had to study the position
and character of a bone, the botanist had to study the outline,
nervation, and microscopic structure of a leaf. Like the great French
naturalist, he had to construct a new science at the very outset of his
great work.
[Illustration: Fig. 158.--Andrias Scheuchzeri.]
The Miocene formations of Switzerland are called _Molasse_ (from the
French _mol_, soft), a term which is applied to a _soft_, incoherent,
greenish sandstone, occupying the country between the Alps and the Jura,
and they may be divided into lower, middle, and upper Miocene; the
middle one is marine, the other two being fresh-water formations. The
upper fresh-water Molasse is best seen at Œningen, in the Rhine valley,
where, according to Sir Roderick Murchison, it ranges ten miles east and
west from Berlingen, on the right bank, to Waugen and to Œningen, near
Stein, on the left bank. In this formation Professor Heer enumerates
twenty-one beds. No. 1, a bluish-grey marl seven feet thick, without
organic remains, resting on No. 2, limestone, with fossil plants,
including leaves of poplar, cinnamon, and pond-weed (_Potamogeton_). No.
3, bituminous rock, with _Mastodon angustidens_. No. 5, two or three
inches thick, containing fossil Fishes. No. 9, the stone in which the
skeleton of the great Salamander _Andrias Scheuchzeri_ (Fig. 158) was
found. Below this, other strata with Fishes, Tortoises, the great
Salamander, as before, with fresh-water Mussels, and plants. In No. 16,
Sir R. Murchison obtained the fossil fox of Œningen, _Galacynus
Œningensis_ (Owen). In these beds Professor Heer had, as early as 1859,
determined 475 species of fossil plants, and 900 insects.
The plants of the Swiss Miocene period have been obtained from a country
not one-fifth the size of Switzerland, yet such an abundance of species,
which Heer reckons at 3,000, does not exist in any area of equal extent
in Europe. It exceeds in variety, he considers, after making every
allowance for all not having existed at the same time, and from other
considerations, the Southern American forests, and rivals such tropical
countries as Jamaica and Brazil. European plants occupy a secondary
place, while the evergreen Oaks, Maples, Poplars, and Plane-trees,
Robinias, and Taxodiums of America and the smaller Atlantic islands,
occupy such an important place in the fossil flora that Unger was
induced to suggest the hypothesis, that, in the Miocene period the
present basin of the Atlantic was dry land--and this hypothesis has been
ably advocated by Heer.
* * * * *
The terrestrial animals which lived in the Miocene period were Mammals,
Birds, and Reptiles. Many new Mammals had appeared since the preceding
period; among others, Apes, Cheiropteras (Bats), Carnivora, Marsupials,
Rodents, Dogs. Among the first we find _Pithecus antiquus_ and
_Mesopithecus_; the Bats, Dogs, and Coati inhabited Brazil and Guiana;
the Rats North America; the Genettes, the Marmots, the Squirrels, and
Opossums having some affinity to the Opossums of America. Thrushes,
Sparrows, Storks, Flamingoes, and Crows, represent the class Birds.
Among the Reptiles appear several Snakes, Frogs, and Salamanders. The
lakes and rivers were inhabited by Perches and Shad. But it is among the
Mammals that we must seek for the most interesting species of animals of
this period. They are both numerous and remarkable for their dimensions
and peculiarities of form; but the species which appeared in the Miocene
period, as in those which preceded it, are now only known by their
fossil remains and bones.
The _Dinotherium_ (Fig. 159), one of the most remarkable of these
animals, is the largest terrestrial Mammal which has ever lived. For a
long time we possessed only very imperfect portions of the skeleton of
this animal, upon the evidence of which Cuvier was induced erroneously
to place it among the Tapirs. The discovery of a lower jaw, nearly
perfect, armed with defensive tusks descending from its lower jaw,
demonstrated that this hitherto mysterious animal was the type of an
altogether new and singular genus. Nevertheless, as it was known that
there were some animals of the ancient world in which both jaws were
armed, it was thought for some time that such was the case with the
Dinotherium. But in 1836, a head, nearly entire, was found in the
already celebrated beds at Eppelsheim, in the Grand Duchy of Hesse
Darmstadt. In 1837 this fine fragment was carried to Paris, and exposed
to public view. It was nearly a yard and a half long, and above a yard
wide. The defences, it was found, were enormous, and were carried at the
anterior extremity of the lower maxillary bone, and much curved inwards,
as in the Morse. The molar teeth were in many respects analogous to
those of the Tapir, and the great suborbital apertures, joined to the
form of the nasal bone, rendered the existence of a proboscis or trunk
very probable. But the most remarkable bone belonging to the Dinotherium
which has yet been found is an omoplate or scapula, which by its form
reminds us of that of the Mole.
[Illustration: Fig. 159.--Dinotherium.]
This colossus of the ancient world, respecting which there has been so
much argument, somewhat approaches the Mastodon; it seems to announce
the appearance of the Elephant; but its dimensions were infinitely
greater than those of existing Elephants, and superior even to those of
the Mastodon and of the Mammoth, both fossil Elephants, the remains of
which we shall have to describe presently.
[Illustration: Fig. 160.--Teeth of Mastodon.]
From its kind of life, and its frugal regimen, this Pachyderm scarcely
merited the formidable name of Dinotherium which has been bestowed on it
by naturalists (from δεινος, _terrible_, θηριον, _animal_). Its size
was, no doubt, frightful enough, but its habits seem to have been
peaceful. It is supposed to have inhabited fresh-water lakes, or the
mouths of great rivers and the marshes bordering their banks by
preference. Herbivorous, like the Elephant, it employed its proboscis
probably in seizing the plants which hung suspended over the waters, or
floated on their surface. We know that the elephants are very partial to
the roots of herbaceous plants which grow in flooded plains. The
Dinotherium appears to have been organised to satisfy the same tastes.
With the powerful natural mattock which Nature had supplied him for
penetrating the soil, he would be able to tear from the bed of the
river, or lake, feculent roots like those of the Nymphæa, or even much
harder ones, for which the mode of articulation of the jaws, and the
powerful muscles intended to move them, as well as the large surface of
the teeth, so well calculated for grinding, were evidently intended
(Fig. 160).
* * * * *
The _Mastodon_ was, to all appearance, very nearly of the size and form
of our Elephant--his body, however, being somewhat longer, while his
limbs, on the contrary, were a little thicker. He had tusks, and very
probably a trunk, and is chiefly distinguished from the existing
Elephant by the form of his molar teeth, which form the most distinctive
character in his organisation. These teeth are nearly rectangular, and
present on the surface of their crown great conical tuberosities, with
rounded points disposed in pairs to the number of four or five,
according to the species. Their form is very distinct, and may be easily
recognised. They do not bear any resemblance to those of the carnivora,
but are like those of herbivorous animals, and particularly those of the
Hippopotamus. The molar teeth are at first sharp and pointed, but when
the conical points are ground down by mastication, they assume the
appearance presented in Fig. 161. When, from continued grinding, the
conical teat-like points are more deeply worn, they begin to assume the
appearance shown in Fig. 160. In Fig. 162 we represent the head and
lower jaw of the Miocene Mastodon; from which it will appear that the
animal had two projecting tusks in the lower jaw, corresponding with two
of much larger dimensions which projected from the upper jaw.
[Illustration: Fig. 161.--Molar teeth of Mastodon, worn.]
It was only towards the middle of the last century that the Mastodon
first attracted attention in Europe. About the year 1705, it is true,
some bones of this animal had been found at Albany, now the capital of
New York, but the discovery attracted little attention. In 1739, a
French officer, M. de Longueil, traversed the virgin forests bordering
the great river Ohio, in order to reach the great river Mississippi, and
the savages who escorted him accidentally discovered on the borders of a
marsh various bones, some of which seemed to be those of unknown
animals. In this turfy marsh, which the natives designated the Great
Salt Lake, in consequence of the many streams charged with salt which
lose themselves in it, herds of wild ruminants still seek its banks,
attracted by the salt--for which they have a great fondness--such being
the reason probably which had caused the accumulation, at this point, of
the remains of so large a number of quadrupeds belonging to these remote
ages in the history of the globe. M. de Longueil carried some of these
bones with him, and, on his return to France, he presented them to
Daubenton and Buffon; they consisted of a femur, one extremity of a
tusk, and three molar teeth. Daubenton, after mature examination,
declared the teeth to be those of a Hippopotamus; the tusk and the
gigantic femur, according to his report, belonged to an Elephant; so
that they were not even considered to be parts of one and the same
animal. Buffon did not share this opinion, and he was not long in
converting Daubenton, as well as other French naturalists, to his views.
Buffon declared that the bones belonged to an Elephant, whose race had
lived only in the primitive ages of the globe. It was then, only, that
the fundamental notion of extinct species of animals, exclusively
peculiar to ancient ages of the world, began to be entertained for the
first time by naturalists--a notion which laid dormant during nearly a
century, before it bore the admirable fruits which have since so
enriched the natural sciences and philosophy.
[Illustration: Fig. 162.--Head of the Mastodon of the Miocene period.