1. _Cycollites elliptica; Thecosmilia rudis; Enallocœnia ramosa;
Meandrina Pyrenaica; Synhelia Sharpeana_. 2. _Orbitoides media;
Lituola nautiloidea; Flabellina rugosa_. 3. _Coscinopora
cupuliformis; Camerospongia fungiformis_.
Among the numerous beings which inhabited the Upper Cretaceous seas
there is one which, by its organisation, its proportions, and the
despotic empire which it would exercise in the bosom of the waters, is
certainly most worthy of our attention. We speak of the _Mosasaurus_,
which was long known as the great animal of _Maestricht_, because its
remains were found near that city in the most modern of the Cretaceous
deposits.
In 1780 a discovery was made in the quarries of Saint Peter’s Rocks,
near Maestricht, of the head of a great Saurian, which may now be seen
in the Museum of Natural History in Paris. This discovery baffled all
the science of the naturalists, at a period when the knowledge of these
ancient beings was still in its infancy. One saw in it the head of a
Crocodile; another, that of a Whale; memoirs and monographs rained down,
without throwing much light on the subject. It required all the efforts
of Adrian Camper, joined to those of the immortal Cuvier, to assign its
true zoological place to the Maestricht animal. The controversy over
this fine fossil engaged the attention of the learned for the remainder
of the last century and far into the present.
Maestricht is a city of the Netherlands, built on the banks of the
Meuse. At the gates of this city, in the hills which skirt the left or
western bank of the river, there rises a solid mass of cretaceous
formation known as Saint Peter’s Rocks. In composition these beds
correspond with the Meudon chalk beds, and they contain similar fossils.
The quarries are about 100 feet deep, consisting in the upper part of
twenty feet abounding in corals and Polyzoa, succeeded by fifty feet of
soft yellowish limestone, furnishing a fine building stone, which has
been quarried from time immemorial, and extends up to the environs of
Liège; this is succeeded by a few inches of greenish soil with
Encrinites, and then by a very white chalk with layers of flints. The
quarry is filled with marine fossils, often of great size.
These fossil remains, naturally enough, attracted the attention of the
curious, and led many to visit the quarries; but of all the discoveries
which attracted attention the greatest interest attached to the gigantic
animal under consideration. Among those interested by the discovery of
these strange vestiges was an officer of the garrison of Maestricht,
named Drouin. He purchased the bones of the workmen as the pick
disengaged them from the rock, and concluded by forming a collection in
Maestricht, which was spoken of with admiration. In 1766, the trustees
of the British Museum, hearing of this curiosity, purchased it, and had
it removed to London. Incited by the example of Drouin, Hoffmann, the
surgeon of the garrison, set about forming a similar collection, and his
collection soon exceeded that of Drouin’s Museum in riches. It was in
1780 that he purchased of the quarrymen the magnificent fossil head,
exceeding six feet in length, which has since so exercised the sagacity
of naturalists.
Hoffman did not long enjoy the fruits of his precious prize, however;
the chapter of the church of Maestricht claimed, with more or less
foundation, certain rights of property; and in spite of all protest, the
head of the _Crocodile of Maestricht_, as it was already called, passed
into the hands of the Dean of the Chapter, named Goddin, who enjoyed
the possession of his antediluvian trophy until an unforeseen incident
changed the aspect of things. This incident was nothing less than the
bombardment and surrender of Maestricht to the Army of the North under
Kleber, in 1794.
The Army of the North did not enter upon a campaign to obtain the crania
of Crocodiles, but it had on its staff a savant who was devoted to such
pacific conquests. Faujas de Saint-Fond, who was the predecessor of
Cordier in the Zoological Chair of the Jardin des Plantes, was attached
to the Army of the North as Scientific Commissioner; and it is suspected
that, in soliciting this mission, our naturalist had in his eye the
already famous head of the Crocodile of the Meuse. However that may be,
Maestricht fell into the hands of the French, and Faujas eagerly claimed
the famous fossil for the French nation, which was packed with the care
due to a relic numbering so many thousands of ages, and dispatched to
the Museum of Natural History in Paris. On its arrival, Faujas undertook
a labour which, as he thought, was to cover him with glory. He commenced
the publication of a work entitled “The Mountain of Saint Peter of
Maestricht,” describing all the fossil objects found in the Dutch quarry
there, especially the _Great Animal_ of Maestricht. He endeavoured to
prove that this animal was a Crocodile.
Unfortunately for the glory of Faujas, a Dutch savant had devoted
himself to the same study. Adrian Camper was the son of a great
anatomist of Leyden, Pierre Camper, who had purchased of the heirs of
the surgeon Hoffman some parts of the skeleton of the animal found in
the quarry of Saint Peter. He had even published in the _Philosophical
Transactions_ of London, as early as 1786, a memoir, in which the animal
is classed as a Whale. At the death of his father, Adrian Camper
re-examined the skeleton, and in a work which Cuvier quotes with
admiration, he fixed the ideas which were until then floating about. He
proved that the bones belonged neither to a Fish, nor a Whale, nor to a
Crocodile, but rather to a particular genus of Saurian Reptiles, or
marine lizards, closely resembling in many important structural
characters, existing Monitors and Iguanas, and peculiar to rocks of the
Cretaceous period, both in Europe and America. Long before Faujas had
finished the publication of his work on _La Montagne de Saint-Pierre_
that of Adrian Camper had appeared, and totally changed the ideas of the
world on this subject. It did not, however, hinder Faujas from
continuing to call his animal the Crocodile of Maestricht. He even
announced, some time after, that Adrian Camper was also of his opinion.
“Nevertheless,” says Cuvier, “it is as far from the Crocodile as it is
from the Iguana; and these two animals differ as much from each other
in their teeth, bones, and viscera, as the ape differs from the cat, or
the elephant from the horse.”
[Illustration: Fig. 145.
_a_, skull of Monitor Niloticus; _b_, under-jaw of same.]
The masterly memoir of Cuvier, while confirming all the views of Camper,
has restored the individuality of this surprising being, which has since
received the name of Mosasaurus, that is to say, Saurian or Lizard of
the Meuse. It appears, from the researches of Camper and Cuvier, that
this reptile of the ancient world formed an intermediate genus between
the group of the Lacertilia, which comprehends the Monitors (represented
in Fig. 145), and the ordinary Lizards; and the Lacertilia, whose
palates are armed with teeth, a group which embraces the _Iguana_ and
the _Anolis_. In respect to the Crocodiles, the Mosasaurus resembles
them in so far as they all belong to the same class of Reptiles.
The idea of a lizard, adapted for living and moving with rapidity at the
bottom of the water, is not readily conceived; but a careful study of
the skeleton of the Mosasaurus reveals to us the secret of this
anatomical mechanism. The vertebræ of the animal are concave in front
and convex behind; they are attached by means of orbicular or arched
articulations, which permitted it to execute easily movements of flexion
in any direction. From the middle of the back to the extremity of the
tail these vertebræ are deficient in the articular processes which
support and strengthen the trunk of terrestrial vertebrated animals:
they resemble in this respect the vertebræ of the Dolphins; an
organisation necessary to render swimming easy. The tail, compressed
laterally at the same time that it was thick in a vertical direction,
constituted a straight rudder, short, solid, and of great power. An
arched bone was firmly attached to the body of each caudal vertebra in
the same manner as in Fishes, for the purpose of giving increased power
to the tail; finally, the extremities of the animal could scarcely be
called feet, but rather paddles, like those of the Ichthyosaurus, the
Plesiosaurus, and the Whale. We see in Fig. 146 that the jaws are armed
with numerous teeth, fixed in their sockets by an osseous base, both
large and solid. Moreover, an altogether peculiar dental system occupies
the vault of the palate, as in the case of certain Serpents and Fishes,
where the teeth are directed backwards, like the barb of a hook, thus
opposing themselves to the escape of prey. Such a disposition of the
teeth sufficiently proves the destructive character of this Saurian.
[Illustration: Fig. 146.--Head of Mosasaurus Camperi.]
The dimensions of this aquatic lizard, estimated at twenty-four feet,
are calculated to excite surprise. But, as we have already seen, the
Ichthyosauri and Teleosauri were of great dimensions, as were also the
Iguanodon and Megalosaurus, which were ten times the size of living
Iguanas. In all these colossal forms we can only see a difference of
dimensions, the aggrandisement of a type; the laws which affected the
organisation of all these beings remain unchanged, they were not errors
of Nature--_monstrosities_, as we are sometimes tempted to call
them--but simply types, uniform in their structure, and adapted by their
dimensions to the physical conditions with which God had surrounded
them.
[Illustration: XXII.--Ideal Landscape of the Cretaceous Period.]
In PLATE XXII. is represented an ideal view of the earth during the
_Upper Cretaceous_ period. In the sea swims the Mosasaurus; Molluscs,
Zoophytes, and other animals peculiar to the period are seen on the
shore. The vegetation seems to approach that of our days; it consists of
Ferns and Cycadeæ (Pterophyllums), mingled with Palms, Willows, and some
dicotyledons of species analogous to those of our present epoch. Algæ,
then very abundant, composed the vegetation of the sea-shore.
We have said that the terrestrial flora of the Upper Cretaceous period
was nearly identical with that of the Lower. The marine flora of these
two epochs included some Algæ, Confervæ, and Naïadæ, among which may be
noted the following species: _Confervites fasciculatus_, _Chondrites
Mantelli_, _Sargassites Hynghianus_. Among the Naïadæ, _Zosterites
Orbigniana_, _Z. lineata_, and several others.
The _Confervæ_ are fossils which may be referred, but with some doubt,
to the filamentous Algæ, which comprehend the great group of the
Confervæ. These plants were formed of simple or branching filaments,
diversely crossing each other; or subdivided, and presenting traces of
transverse partitions.
The _Chondrites_ are, perhaps, fossil Algæ, with thick, smooth branching
fronds, pinnatifid, or divided into pairs, with smooth cylindrical
divisions, and resembling _Chondrus_, _Dumontia_, and _Halymenia_ among
living genera.
The _Sargassites_, finally, have been vaguely referred to the genus
_Sargassum_, so abundant in tropical seas. These Algæ are distinguished
by a filiform, branched, or ramose stem, bearing foliaceous appendages,
regular, often petiolate, and altogether like leaves, and globular
vesicles, supported by a small stalk.
* * * * *
The rocks which actually represent the _Upper Cretaceous period_ divide
themselves naturally into six series; but British and French geologists
make some distinction: the former dividing them into 1, _Maestricht_ and
_Faxoe_ beds, said not to occur in England; 2, _White Chalk_, with
_flints_; 3, _White Chalk_, without _flint_s; 4, _Chalk Marl_; 5, _Upper
Greensand_; and 6, _Gault_. The latter four are divided by foreign
geologists into 1, _Turonian_; 2, _Senonian_; 3, _Danian_.
The _Gault_ is the lowest member of the Upper Cretaceous group. It
consists of a bluish-black clay mixed with greensand, which underlies
the Upper Greensand. Near Cambridge, where the Gault is about 200 feet
thick, a layer of shells, bones, and nodules, called the “Coprolite
Bed,” from nine inches to a foot thick, represents the Upper Greensand,
and rests on the top of the Gault Clay. These nodules and fossils are
extensively worked on account of the phosphatic matter they contain, and
when ground and converted into superphosphate of lime they furnish a
very valuable agricultural manure. The Gault attains a thickness of
about 100 feet on the south-east coast of England. It extends into
Devonshire, Mr. Sharpe considering the Black Down beds of that country
as its equivalents. It shows itself in the Departments of the
Pas-de-Calais, the Ardennes, the Meuse, the Aube, the Yonne, the Ain,
the Calvados, and the Seine-Inférieure. It presents very many distinct
mineral forms, among which two predominate: green sandstone and blackish
or grey clays. It is important to know this formation, for it is at this
level that the Artesian waters flow in the wells of Passy and Grenelle,
near Paris.
The _glaucous_ chalk, or Upper Greensand, which is represented typically
in the departments of the Sarthe, of the Charente-Inférieure, of the
Yonne and the Var, is composed of quartzose sand, clay, sandstone, and
limestone. In this formation, at the mouth of the Charente, we find a
remarkable bed, which has been described as a submarine forest. It
consists of large trees with their branches imbedded horizontally in
vegetable matter, containing kidney-shaped nodules of amber, or
fossilised resin.
The _Turonian_ beds are so named because the province of Touraine,
between Saumur and Montrichard, possesses the best-developed type of
this strata. The mineralogical composition of the beds is a fine and
grey marly chalk, as at Vitry-le-François; of a pure white chalk, with a
very fine grain, slightly argillaceous, and poor in fossils, in the
Departments of the Yonne, the Aube, and the Seine-Inférieure; granular
tufaceous chalk, white or yellowish, mixed with spangles of mica, and
containing Ammonites, in Touraine and a part of the Department of the
Sarthe; white, grey, yellow, or bluish limestone, inclosing Hippurites
and Radiolites. In England the Lower Chalk passes also into Chalk Marl,
with Ammonites, and then into beds known as the Upper Greensand,
containing green particles of glauconite, mixed, in Hampshire and
Surrey, with much calcareous matter. In the Isle of Wight this formation
attains a thickness of 100 feet. The _Senonian_ beds take their name
from the ancient _Senones_. The city of Sens is in the centre of the
best-characterised portion of this formation; Epernay, Meudon, Sens,
Vendôme, Royau, Cognac, Saintes, are the typical regions of the
formation in France. In the Paris basin, inclusive of the Tours beds, it
attains a thickness of upwards of 1,500 feet, as was proved by the
samples brought up, during the sinking of the Artesian well, at
Grenelle, by the borings.
In its geographical distribution the Chalk has an immense range; fine
Chalk of nearly similar aspect and composition being met with in all
directions over hundreds of miles, alternating in its lower beds with
layers of flints. In England the higher beds usually consist of a
pure-white calcareous mass, generally too soft for building-stone, but
sometimes passing into a solid rock.
The _Danian_ beds, which occupy the summit of the scale in the
Cretaceous formation, are finely developed at Maestricht, on the Meuse;
and in the Island of Zeeland, belonging to Denmark; where they are
represented by a slightly yellowish, compact limestone, quarried for the
construction of the city of Faxoe. It is slightly represented in the
Paris basin at Meudon, and Laversines, in the Department of the Oise, by
a white and often rubbly limestone known as _pisolitic limestone_. In
this formation _Ammonites Danicus_ is found. The yellowish sandy
limestone of Maestricht is referred to the _Danian_ type. Besides
Molluscs, Polyps, and Polyzoa (Bryozoa), this limestone contains remains
of Fishes, Turtles, and Crocodiles. But what has rendered this rock so
celebrated was that it contained the remains of the _great animal of
Mæstricht_, the Mæsasaurus.
At the close of the geological period, whose natural physiognomy we have
thus traced, Europe was still far from displaying the configuration
which it now presents. A map of the period would represent the great
basin of Paris (with the exception of a zone of Chalk), the whole of
Switzerland, the greater part of Spain and Italy, the whole of Belgium,
Holland, Prussia, Hungary, Wallachia, and Northern Russia, as one vast
sheet of water. A band of Jurassic rocks still connected France and
England at Cherbourg--which disappeared at a later period, and caused
the separation of the British Islands from what is now France.
[Illustration: Fig. 147.--Exogym conica. Upper Greensand and Gault, from
Blackdown Hill.]