WHAT CREATURES ONCE LIVED WHERE DORSETSHIRE NOW IS.
I will show you a picture of what creatures were once living where the
town of Lyme Regis, in Dorsetshire, now stands, and tell you something
about their structure and their habits. You may perhaps be ready to
think that a great deal of what we profess to know concerning them,
is the work of fancy, but I can assure you it is not, and by and by I
will endeavour to convince you that there is reason enough for you to
believe what I tell you.
THE ICHTHYOSAURUS.
That large animal lying on the ground, is called the _Icthyosaurus_,
from two Greek words signifying _Fish-Lizard_, in consequence of his
possessing some of the peculiarities of both fishes and lizards.
The usual length of this creature was from twenty to thirty feet. It
possessed a most surprising combination of the powers and qualities of
different animals which are now in existence. In its general form and
character it must have been something like the modern porpoise; but it
had the teeth of a crocodile, the head of a lizard, the back-bone of a
fish, and the fins or _paddles_, of a whale.
I shall spend some little time in explaining to you each of these
particulars, that you may see how wisely all the parts of living things
are framed to supply their wants, and adapt them to the circumstances
in which they are placed.
The head was not very different from that of a crocodile, or lizard, in
its general shape. The teeth were precisely like those of a crocodile,
and grew up in the same manner. Creatures of this sort lead a ruffian
sort of life, always biting something or other, and as they live very
much in the dark at the bottom of the water, perhaps now and then snap
at a stone or a piece of hard wood by mistake, and often break their
teeth; and in order therefore to keep them in constant repair, they
have a fresh set once a year, or at very short intervals, so that they
are always growing. The young tooth _a_, springs up inside the old one
_b_, till it becomes so large that it splits its predecessor, and the
pieces fall off, just as the covering of some sorts of buds falls off
as the flower expands, as you will see in this cut, representing one of
the fossil teeth.
[Illustration]
You must have noticed in the picture the great length of his snout.
In a jaw-bone of such amazing length which was to be applied to such
violent purposes, it was necessary there should be great strength.
There were two ways of obtaining this: one would have been by having
the bones very hard and stout; but this would not do, because they
would then have been so heavy that the animal would have found
difficulty in raising his head to the surface of the water for the
purpose of breathing, since it would have overbalanced the other part
of his body. The other contrivance, which was the one adopted by the
wisdom of the Creator, was to make the jaws consist of several thin
bones, _a_, _b_, _c_, _d_, strongly bound together, and terminating in
succession like the plates of steel of which a carriage spring is made.
There are accordingly six of these bones thus disposed.
[Illustration]
But this was not all, the principal middle bone marked _b_, instead
of having its fibres run straight, parallel with the others, had them
placed in a slanting position, and thus there was additional firmness
given to the jaw by what ship-builders would call _diagonal bracing_, a
contrivance that you may often see used in the construction of houses
and ships.
If you have ever seen a crocodile open its mouth, and then snap
together its long thin jaws, so as to make you start with the noise,
you will see how necessary all these contrivances must be for him and
the Icthyosaurus, whose jaws were still thinner, to prevent them from
breaking their bones.
This however is not at all more wonderful than the eye, which in the
old-fashioned animal I have been describing, was much larger than that
of the crocodile, and not unfrequently bigger than a man's head. From
the very great quantity of light which such a large surface would
receive, the creature's power of seeing must have been very great. And
besides this advantage, it had the same faculty as is possessed by the
golden eagle, the turtle, the tortoise, and the lizard, of pressing the
eye forward to render it more convex. In man and most animals, the eye
is placed in a fixed cavity of thin bone, something like an egg-cup,
but in the Icthyosaurus, the cavity was formed by several bones not
quite touching each other; (as you may see in the last cut, and in
figure 2, you have two of the bones by themselves, taken out of the
socket of the eye;) and there were muscles to draw these bones closer
together; so that by making the cup less deep, the eye was thrust
forward and made to swell out in the middle. This is illustrated in
the ball _b_, which is pressed outwards, by drawing the plates of bone
_cc_, together at _o_, close than those which have the ball _a_ between
them.
[Illustration]
You must have seen that the more convex magnifying glasses are, the
more they magnify, and the nearer you must hold them to the object you
are looking at. By this contrivance, the eye of the Icthyosaurus could
be made at pleasure into a microscope, so as to see with wonderful
quickness things which were quite close to it, by pushing it forward
and rendering it more convex; or it could be made into a telescope like
the eyes of some persons who are long-sighted, for seeing what is at a
greater distance, by drawing it back.
In all these particulars you may see how the skill of man leads him
to adopt the same plans to produce the same ends in the works of
art, as God has adopted before him in the works of nature, without
his being conscious of copying them; and this should remind you that
man was created in the image of his Maker. If man had never made a
carriage-spring, or a diagonal bracing, he would not have understood
the structure of the jaw of the Icthyosaurus; and if he had never
invented the telescope, he would not have been able to explain the
construction of the eye.
You have now seen the points in which the Icthyo-saurus chiefly
resembled a crocodile or lizard; from which the latter half of its name
is derived, _saurus_, _a lizard_. I must now tell you something of
those parts in which it is like a fish, from which it takes the other
part of its name, _icthy_, for _icthus_, a fish.
You know that crocodiles live a good part of their time on land, and
they therefore have feet and a back-bone like land animals, which
enable them to walk better, but do not allow them to swim so well as
fish. The back-bone is heavy and firm, and each of the bones composing
it has one side slightly hollow, and the other side swelling out to
fit into the hollow in the one that comes next to it. But in fish both
sides of the bones are hollow, and they are joined together by gristle,
as you can easily see in the fish that are commonly eaten; this renders
the back-bone much more flexible and lighter, and therefore better
adapted for an animal always swimming. That of the Icthyosaurus was
formed in the same manner, and we therefore judge that he spent his
whole life in the water; for a back-bone so formed, would not have been
able to support such a great heavy body when walking on the land.
The fins, or paddles, were very curious, and much like those of the
whale; they consisted of above a hundred small bones strongly united
together, in a sort of pavement enclosed in a strong skin, and not
divided into toes, as you may observe in this representation of the
entire skeleton.
[Illustration]
You may see many specimens of the skeleton itself in the British
Museum.
The Icthyosaurus was a great tyrant, and used to prey on every creature
that came within his reach; this is known by the fossil remains
found in the inside of his body. He used at times even to act the
cannibal, and eat his own relations, for a large one has been dug out
of the cliff at Lyme Regis, with part of a small one in his stomach
undigested; he must have been altogether a very unamiable character.
But as his family has been so long extinct, and we are told that we
ought to say nothing but what is good concerning the dead, I shall not
say any more about him, leaving you to form your own conclusions from
what I have related to you.
THE PLESIOSAURUS.
Those still more strange looking animals with very long necks, which
are represented swimming in the water, have been named _Plesiosauri_, a
word signifying, _related to_, or _closely resembling_, a lizard. There
are some nearly perfect specimens in the British Museum, and this is a
representation made up by taking the uninjured parts of several, so as
to make up a perfect whole.
[Illustration]
Taking it altogether, there is not one of the fossil animals so much
unlike anything at present known to exist. Its usual length was from 9
to 15 feet, but it was at times very much larger.
The head was much shorter in proportion than that of the Icthyosaurus,
being more like that of the guana, the lizard which people eat in the
West Indies. The neck must have been longer than that of any living
animal, not even excepting the swan; it contained thirty-three bones,
or _vertebræ_, while the whole of the rest of the back-bone in the body
and tail, contained only fifty-seven.
The faces of these vertebræ were nearly flat, and not hollow like those
of the Icthyosaurus, which would better enable the animal to exist on
land, and it appears to have moved about in the same manner as seals
do. From some very ingenious observations on certain parts of its
anatomy, (which if I were to endeavour to explain to you, you would not
understand, unless you possessed a great deal of anatomical knowledge,)
naturalists have supposed that it used to change the colour of its skin
like the chameleon. Its paddles were almost exactly like those of the
turtle, and its body was something of the same shape, but not quite so
wide.
From its long neck, which, although it was strengthened by the solid
joints and peculiar shapes of the bones, was not very strong, and
its small head and jaws, the Plesiosaurus could not have been near a
match for its neighbour, the Icthyosaurus, in combat, even when the
individuals were of the same size; neither would its form adapt it for
cutting through the water so quickly. It must, therefore, no doubt,
have often fallen a prey to that voracious monster. Perhaps, however,
it often played him a trick when he was pursuing it by running on shore
out of his reach; or it might mostly have kept out of his way in very
shallow water amongst the rushes and reeds, where it could every now
and then dart its long neck like a swan, down at the little fish that
came near it; or else suddenly reaching aloft into the air, it may have
seized upon some unlucky insect, or Pterodactyle, (a sort of bat of
which I shall presently speak) and then laid down as quiet under the
rushes as if nothing had happened, waiting for its next mouthful.
THE PTERODACTYLE.
That odd-looking creature which is flying in the air over the heads of
the Plesiosauri, has been called the Pterodactyle, which signifies
_wing-fingered_. There were several varieties, of different sizes and
figures, from that of a snipe to that of a raven. The most remarkable
of them was indeed a curious creature, and so you will say if you look
at the picture of his skeleton.
[Illustration]
He was more like a bat in his general shape and habits, than anything
else we know of, but was very different in a great many respects.
He had a head like a lizard, with a long snout and sharp teeth; his
ribs were round and thread-like, not flat like those of birds and bats;
his eyes were large; and his wings like a bat's, being a membrane or
skin, stretched out by one very long toe on each of his fore-feet. In
order to support his long head, there were strong cords running down
each side of the vertebræ of his neck, such as are found in some modern
birds, as is known by the forms of the bones to which the ends of them
were attached. His toes ended in sharp claws, and he had also claws at
his two principal joints, so that he could catch hold of the branches
of trees with them, as bats do. These creatures used principally to
feed upon large dragon flies, beetles, and the other insects, of which
the remains are found, and some of which are represented in the picture.
There were also living at the same time with these creatures, several
kinds of tortoises, and fish in immense varieties. The whole district
where the south coast of England now is, seems to have then been a
marsh with no vegetation but sea-weeds, reeds, and the like; and its
only inhabitants were, fish, reptiles, and insects.
After the races of animals which we have mentioned, became extinct,
a period followed in which they were succeeded by some monstrous
creatures, like lizards in all respects, except that they were fitted
to live in the water by the construction of their back-bone, their
having lungs of the same kind as those of fishes, and the possession of
fins. One of these, called the Iguanodon, was sometimes seventy feet
long. It had a little horn near the end of its snout, placed something
like the horn of a rhinoceros, and must have borne considerable
resemblance in its general form to the guana, which I mentioned before.
Their bones and teeth, are found at Lewes, in Sussex, and in the Isle
of Wight, where you may pick them up on the shore, as you can the bones
of Icthyosauri and Plesiosauri, at Lyme Regis, though not in such great
numbers.
We are indebted for a great deal of what I have told you about the
animals that once lived where Dorsetshire is now, to a lady, Miss
Anning, who spends nearly her whole time in collecting fossils out of
the cliffs. No one ought to go near Lyme Regis without visiting her
collection.
[Illustration: PLATE II.
EXTINCT ANIMALS.]