In this new phase of the revolutions of the globe, the animated beings
on its surface differ much from those which belonged to the Primary
epoch. The curious Crustaceans which we have described under the name of
_Trilobites_ have disappeared; the molluscous Cephalopods and
Brachiopods are here few in number, as are the Ganoid and Placoid
Fishes, whose existence also seems to have terminated during this
period, and vegetation has undergone analogous changes. The cryptogamic
plants, which reached their maximum in the Primary epoch, become now
less numerous, while the Conifers experienced a certain extension. Some
kinds of terrestrial animals have disappeared, but they are replaced by
genera as numerous as new. For the first time the Turtle appears in the
bosom of the sea, and on the borders of lakes. The Saurian reptiles
acquire a great development; they prepare the way for those enormous
Saurians, which appear in the following period, whose skeletons present
such vast proportions, and such a strange aspect, as to strike with
astonishment all who contemplate their gigantic, and, so to speak,
awe-inspiring remains.
The _Variegated Sandstone_, or Bunter, contains many vegetable, but few
animal, remains, although we constantly find imprints of the footsteps
of the Labyrinthodon.
The lowest Bunter formation shows itself in France, in the Pyrenees,
around the central plateau in the Var, and upon both flanks of the
Vosges mountains. It is represented in south-western and central
Germany, in Belgium, in Switzerland, in Sardinia, in Spain, in Poland,
in the Tyrol, in Bohemia, in Moravia, and in Russia. M. D’Orbigny
states, from his own observation, that it covers vast surfaces in the
mountainous regions of Bolivia, in South America. It is recognised in
the United States, in Columbia, in the Great Antilles, and in Mexico.
The Bunter in France is reduced to the variegated sandstone, except
around the Vosges, in the Var, and the Black Forest, where it is
accompanied by the Muschelkalk. In Germany it furnishes building-stone
of excellent quality; many great edifices, in particular the cathedrals,
so much admired on the Rhine--such, for example, as those of Strasbourg
and Fribourg--are constructed of this stone, the sombre tints of which
singularly relieve the grandeur and majesty of the Gothic architecture.
Whole cities in Germany are built of the brownish-red stones drawn from
its mottled sandstone quarries. In England, in Scotland, and in Ireland
this formation extends from north to south through the whole length of
the country. “This old land,” says Professor Ramsay,[54] “consisted in
great part of what we now know as Wales, and the adjacent counties of
Hereford, Monmouth, and Shropshire; of part of Devon and Cornwall,
Cumberland, the Pennine chain, and all the mountainous parts of
Scotland. Around old Wales, and part of Cumberland, and probably all
round and over great part of Devon and Cornwall, the New Red Sandstone
was deposited. Part, at least, of this oldest of the Secondary rocks was
formed of the material of the older Palæozoic strata, that had then
risen above the surface of the water. The New Red Sandstone series
consists in its lower members of beds of red sandstone and conglomerate,
more than 1,000 feet thick, and above them are placed red and green
marls, chiefly red, which in Germany are called the Keuper strata, and
in England the New Red Marl. These formations range from the mouth of
the Mersey, round the borders of Wales, to the estuary of the Severn,
eastwards into Warwickshire, and thence northwards into Yorkshire and
Northumberland, along the eastern border of the Magnesian Limestone.
They also form the bottom of the valley of the Eden, and skirt
Cumberland on the west; in the centre of England the unequal hardness of
its sub-divisions sometimes giving rise to minor escarpments,
overlooking plains and undulating grounds of softer strata.”
[54] “The Physical Geography and Geology of Great Britain,” 2nd ed.,
p. 60.
“Different members of the group rest in England, in some region or
other,” says Lyell, “on almost every principal member of the Palæozoic
series, on Cambrian, Silurian, Devonian, Carboniferous, and Permian
rocks; and there is evidence everywhere of disturbance, contortion,
partial upheaval into land, and vast denudations which the older rocks
underwent before and during the deposition of the successive strata of
the New Red Sandstone group.” (“Elements of Geology,” p. 439.)
The _Muschelkalk_ consists of beds of compact limestone, often greyish,
sometimes black, alternating with marl and clay, and commonly containing
such numbers of shells that the name of shelly limestone (_Muschelkalk_)
has been given to the formation by the Germans. The beds are sometimes
magnesian, especially in the lower strata, which contain deposits of
gypsum and rock-salt.
The seas of this sub-period, which is named after the innumerable masses
of shells inclosed in the rocks which it represents, included, besides
great numbers of Mollusca, Saurian Reptiles of twelve different genera,
some Turtles, and six new genera of Fishes clothed with a cuirass. Let
us pause at the Mollusca which peopled the Triassic seas.
[Illustration: Fig. 81.--Ceratites nodosus. (Muschelkalk.)]
Among the shells characteristic of the Muschelkalk period, we mention
_Natica Gaillardoti_, _Rostellaria antiqua_, _Lima striata_, _Avicula
socialis_, _Terebratula vulgaris_, _Turbonilla dubia_, _Myophoria
vulgaris_, _Nautilus hexagonalis_, and _Ceratites nodosus_. The
_Ceratites_, of which a species is here represented (Fig. 81), form a
genus closely allied to the _Ammonites_, which seem to have played such
an important part in the ancient seas, but which have no existence in
those of our era, either in species or even in genus. This Ceratite is
found in the Muschelkalk of Germany, a formation which has no equivalent
in England, but which is a compact greyish limestone underlying the
saliferous rocks in Germany, and including beds of dolomite with gypsum
and rock-salt.
The _Mytilus_ or _Mussel_, which properly belonged to this age, are
acephalous (or headless) Molluscs with elongated triangular shells, of
which there are many species found in our existing seas. _Lima_,
_Myophoria_, _Posidonia_, and _Avicula_, are acephalous Molluscs of the
same period. The two genera _Natica_ and _Rostellaria_ belong to the
Gasteropoda, and are abundant in the Muschelkalk in France, Germany, and
Poland.
Among the Echinoderms belonging to this period may be mentioned
_Encrinus moniliformis_ and _E. liliiformis_, or _lily encrinite_ (Fig.
82), whose remains, constituting in some localities whole beds of rock,
show the slow progress with which this zoophyte formed beds of limestone
in the clear seas of the period. To these may be added, among the
Mollusca, _Avicula subcostata_ and _Myophoria vulgaris_.
In the Muschelkalk are found the skull and teeth of _Placodus gigas_, a
reptile which was originally placed by Agassiz among the class of
Fishes; but more perfect specimens have satisfied Professor Owen that it
was a Saurian Reptile.
It may be added, that the presence of a few genera, peculiar to the
Primary epoch, which entirely disappeared during the sub-period, and
the appearance for the first time of some other animals peculiar to the
Jurassic period, give to the Muschelkalk fauna the appearance of being
one of passage from one period to the other.
[Illustration: Fig. 82.--Encrinus liliiformis.]
The seas, then, contained a few Reptiles, probably inhabitants of the
banks of rivers, as _Phytosaurus_, _Capitosaurus_, &c., and sundry
Fishes, as _Sphœrodus_ and _Pycnodus_. In this sub-period we shall say
nothing of the Land-Turtles, which for the first time now appear; but,
we should note, that at the Bunter period a gigantic Reptile appears, on
which the opinions of geologists were for a long while at variance. In
the argillaceous rocks of the Muschelkalk period imprints of the foot of
some animal were discovered in the sandstones of Storeton Hill, in
Cheshire, and in the New Red Sandstone of parts of Warwickshire, as well
as in Thuringia, and Hesseburg in Saxony, which very much resembled the
impression that might be made in soft clay by the outstretched fingers
and thumb of a human hand. These traces were made by a species of
Reptile furnished with four feet, the two fore-feet being much broader
than the hinder two. The head, pelvis, and scapula only of this
strange-looking animal have been found, but these are considered to have
belonged to a gigantic air-breathing reptile closely connected with the
Batrachians. It is thought that the head was not naked, but protected by
a bony cushion; that its jaws were armed with conical teeth, of great
strength and of a complicated structure. This curious and
uncouth-looking creature, of which the woodcut Fig. 83 is a restoration,
has been named the _Cheirotherium_, or _Labyrinthodon_, from the
complicated arrangement of the cementing layer of the teeth. (See also
Fig. 1, p. 12.)
Another Reptile of great dimensions--which would seem to have been
intended to prepare the way for the appearance of the enormous Saurians
which present themselves in the Jurassic period--was the _Nothosaurus_,
a species of marine Crocodile, of which a restoration has been attempted
in PLATE XIII. opposite.
[Illustration: XIII.--Ideal Landscape of the Muschelkalk Sub-period.]
It has been supposed, from certain impressions which appear in the
Keuper sandstones of the Connecticut river in North America, that
Birds made their appearance in the period which now occupies us; the
flags on which these occur by thousands show the tracks of an animal of
great size (some 20 inches long and 4½ feet apart), presenting the
impression of three toes, like some of the Struthionidæ or Ostriches,
accompanied by raindrops. No remains of the skeletons of birds have been
met with in rocks of this period, and the footprints in question are all
that can be alleged in support of the hypothesis.
[Illustration: Fig. 83.--Labyrinthodon restored. One-twentieth natural
size.]
M. Ad. Brongniart places the commencement of dicotyledonous gymnosperm
plants in this age. The characteristics of this Flora consist in
numerous Ferns, constituting genera now extinct, such as _Anomopteris_
and _Crematopteris_. The true _Equiseta_ are rare in it. The Calamites,
or, rather, the _Calamodendra_, abound. The gymnosperms are represented
by the genera _Conifer_, _Voltzia_, and _Haidingera_, of which both
species and individuals are very numerous in the formation of this
period.
Among the species of plants which characterise this formation, we may
mention _Neuropteris elegans_, _Calamites arenaceus_, _Voltzia
heterophylla_, _Haidingera speciosa_. The _Haidingera_, belonging to the
tribe of _Abietinæ_, were plants with large leaves, analogous to those
of our _Damara_, growing close together, and nearly imbricated, as in
the _Araucaria_. Their fruit, which are cones with rounded scales, are
imbricated, and have only a single seed, thus bearing out the strong
resemblance which has been traced between these fossil plants, and the
Damara.
The _Voltzias_ (Fig. 84), which seem to have formed the greater part of
the forests were a genus of Cupressinaceæ, now extinct, which are well
characterised among the fossil Conifers of the period. The alternate
spiral leaves, forming five to eight rows sessile, that is, sitting
close to the branch and drooping, have much in them analogous to the
_Cryptomerias_. Their fruit was an oblong cone with scales, loosely
imbricated, cuneiform or wedge-shaped, and, commonly, composed of from
three to five obtuse lobes. In Fig. 84 we have a part of the stem, a
branch with leaves and cone. In his “Botanic Geography,” M. Lecoq thus
describes the vegetation of the ancient world in the first period of the
Triassic age: “While the variegated sandstone and mottled clays were
being slowly deposited in regular beds by the waters, magnificent Ferns
still exhibited their light and elegantly-carved leaves. Divers
_Protopteris_ and majestic _Neuropteris_ associated themselves in
extensive forests, where vegetated also the _Crematopteris typica_ of
Schimper, the _Anomopteris Mongeotii_ of Brongniart, and the pretty
_Trichomanites myriophyllum_ (Göppert). The Conifers of this epoch
attain a very considerable development, and would form graceful forests
of green trees. Elegant monocotyledons, representing the forms of
tropical countries, seem to show themselves for the first time, the
_Yuccites Vogesiacus_ of Schimper constituted groups at once thickly
serried and of great extent.
“A family, hitherto doubtful, appears under the elegant form of
_Nilssonia Hogardi_, Schimp.; _Ctenis Hogardi_, Brongn. It is still seen
in the _Zamites Vogesiacus_, Schimp.; and the group of the Cycads
sharing at once in the organisation of the Conifers and the elegance of
the Palms, now decorate the earth, which reveals in these new forms its
vast fecundity. (See Fig. 72, p. 168.)
[Illustration: Fig. 84.--Branch and cone of Voltzia restored.]
“Of the herbaceous plants which formed the undergrowth of the forests,
or which luxuriated in its cool marshes, the most remarkable is the
_Ætheophyllum speciosum_, Schimp. Their organisation approximates to
the Lycopodiaceæ and Thyphaceæ, the _Ætheophyllum stipulare_, Brongn.,
and the curious _Schizoneura paradoxa_, Schimp. Thus we can trace the
commencement of the reign of the Dicotyledons with naked seeds, which
afterwards become so widely disseminated, in a few Angiosperms, composed
principally of two families, the Conifers and Cycadeaceæ, still
represented in the existing vegetation. The former, very abundant at
first, associated themselves with the cellular Cryptogams, which still
abound, although they are decreasing, then with the Cycadeaceæ, which
present themselves slowly, but will soon be observed to take a large
part in the brilliant harmonies of the vegetable kingdom.”
The engraving at page 191 (PLATE XIII.) gives an idealised picture of
the plants and animals of the period. The reader must imagine himself
transported to the shores of the Muschelkalk sea at a moment when its
waves are agitated by a violent but passing storm. The reflux of the
tide exposes some of the aquatic animals of the period. Some fine
Encrinites are seen, with their long flexible stems, and a few Mytili
and Terebratulæ. The Reptile which occupies the rocks, and prepares to
throw itself on its prey, is the _Nothosaurus_. Not far from it are
other reptiles, its congeners, but of a smaller species. Upon the dune
on the shore is a fine group of the trees of the period, that is, of
_Haidingeras_, with large trunks, with drooping branches and foliage, of
which the cedars of our own age give some idea. The elegant _Voltzias_
are seen in the second plane of this curtain of verdure. The Reptiles
which lived in these primitive forests, and which would give to it so
strange a character, are represented by the _Labyrinthodon_, which
descends towards the sea on the right, leaving upon the sandy shore
those curious tracks which have been so wonderfully preserved to our
days.
The footprints of the reptilian animals of this period prove that they
walked over moist surfaces; and, if these surfaces had been simply left
by a retiring tide, they would generally have been obliterated by the
returning flood, in the same manner that is seen every day on our own
sandy shores. It seems more likely that the surfaces, on which fossil
footprints are now found, were left bare by the summer evaporation of a
lake; that these surfaces were afterwards dried by the sun, and the
footprints hardened, so as to ensure their preservation, before the
rising waters brought by flooded muddy rivers again submerged the low
flat shores and deposited new layers of salt, just as they do at the
present day round the Dead Sea and the Salt Lake of Utah.
[Illustration: XIV.--Ideal Landscape of the Keuper Sub-period.]