THE GREAT FISH-LIZARDS.
"Berossus, the Chaldæan saith: A time was when the universe
was darkness and water, wherein certain animals of frightful
and compound forms were generated. There were serpents and
other creatures with the mixed shapes of one another, of
which pictures are kept in the temple of Belus at
Babylon."--_The Archaic Genesis._
Visitors to Sydenham, who have wandered about the spacious gardens so
skilfully laid out by the late Sir Joseph Paxton, will be familiar
with the great models of extinct animals on the "geological island."
These were designed and executed by that clever artist, Mr. Waterhouse
Hawkins, who made praiseworthy efforts to picture to our eyes some of
the world's lost creations, as restored by the genius of Sir Richard
Owen and other famous naturalists. His drawings of extinct animals may
yet be seen hanging on the walls of some of our provincial museums;
and doubtless others still linger among the natural history
collections of schools and colleges.
Lazily basking in the sun, when it condescends to shine, and resting
his clumsy carcase on the ground that forms the shore near the said
geological island at Sydenham, may be seen the old fish-lizard, or
Ichthyosaurus, that forms the subject of the present chapter. He looks
awkward on land, as if longing to get into his native element once
more, and cleave its waters with his powerful tail-fin. His "flippers"
seem too weak to enable him to crawl on land. Moreover, the most
recent discoveries of Dr. Fraas lead us to conclude that the
Ichthyosaur never ventured to leave the "briny ocean" to bask upon the
land.
This great uncouth beast presents some curious anomalies in his
constitution, being planned on different lines to anything now living,
and presenting, as so many other extinct animals do, a mixture, or
fusion, of types that greatly puzzled the learned men of the time when
his remains were first brought to light, after their long entombment
in the Lias rocks forming the cliffs on the coast of Dorset. Some have
christened him a "sea-dragon," and such indeed he may be considered.
But the name Ichthyosaurus, given above, has received the sanction of
high authority, and, moreover, serves to remind us of the fact that,
although in many respects a lizard, he yet retains in his bony
framework the traces of a remote fishy ancestry. So we will call him a
fish-lizard.
We remember in our young days the amiable endeavours of Mr. "Peter
Parley" to introduce us to the wonders of creation; and his account of
the Ichthyosaurus particularly impressed itself on our youthful
imagination. How surprised that inestimable instructor of youth would
be could he now see the still more wonderful remains that have been
brought to light from Europe, Asia, Africa, and America!
The curious quotation given at the head of the present chapter refers
to a widespread belief, prevalent among the highly civilised nations
of antiquity, that the world was once inhabited by dragons, or other
monsters "of mixed shape" and characters. To the student of ancient
history traces of this curious belief will be familiar. Sir Charles
Lyell refers to such a belief when he says, in his _Principles of
Geology_, "The Egyptians, it is true, had taught, and the Stoics had
repeated, that the earth had once given birth to some monstrous
animals that existed no longer." It may be surprising to some, but it
is undoubtedly the fact, that modern scientific truths were partly
anticipated by the civilised nations of long ago. Take the ideas of
the ancients as interpreted from the records of Egypt, Chaldæa,
India, and China; and you will find that our discoveries in geology,
astronomy, and ethnology go far to prove that the traditions of these
ancient peoples, however derived, after making due allowance for
Oriental allegory and poetic hyperbole, are not far from the truth. To
the Babylonian tradition of the monstrous forms of life at first
created we have already alluded; but in other fields of discovery we
find the same foreshadowing of discoveries made in our own day. Take
the vast cycles of Egyptian tradition, wherein the stars returned to
their places after a circle of constant change, only to start again on
their unwearied round; the atomic theory of Lucretius, now expanded
and incorporated into modern chemistry; or the philosopher's pregnant
saying--_Omne vivum ex ovo_ ("Every living thing comes from an egg").
These and other examples might be cited to show how true the old
saying is, "There is nothing new under the sun." In the writings of
ancient authors may be found singular notices of bones and skeletons
found in "the bowels of the earth," which are referred to an imaginary
era of long ago, when giants of huge dimensions walked this earth. One
is inclined sometimes to wonder whether the old fables of griffins and
horrid dragons may not be to some extent based upon the occasional
discovery, in former times, of fossil bones, such as evidently
belonged to animals the like of which are not to be seen nowadays.
(See chaps. xiii. and xiv.)
The illustrious Cuvier, in his day, considered the fish-lizard to be
one of the most heteroclite and monstrous animals ever discovered. He
said of this creature that it possessed the snout of a dolphin, the
teeth of a crocodile, the head and breast-bone of a lizard, the
paddles of a whale or dolphin, and the vertebræ of a fish! No wonder
that naturalists and palæontologists, whose realm is the natural
history of the past, were obliged to make a new division, or order, of
reptiles to accommodate the fish-lizard. It is obvious that a creature
with such very "mixed" relationships would be out of place in any of
the four orders into which living reptiles, as represented by turtles,
snakes, lizards, and crocodiles are divided. Here is what Professor
Blackie says of the Ichthyosaurus--
"Behold, a strange monster our wonder engages!
If dolphin or lizard your wit may defy.
Some thirty feet long, on the shore of Lyme-Regis,
With a saw for a jaw, and a big staring eye.
A fish or a lizard? An ichthyosaurus,
With a big goggle eye, and a very small brain,
And paddles like mill-wheels in chattering chorus,
Smiting tremendous the dread-sounding main."
A glance at our restoration, Plate II., will show that the fish-lizard
was a powerful monster, well endowed with the means of propelling
itself rapidly through the water as it sought its living prey, to
seize it within those cruel jaws. The long and powerful tail was its
chief organ of propulsion; but the paddles would also be useful for
this purpose, as well as for guiding its course. The pointed head and
generally tapering body suggests a capability of rapid movement
through the water; and since we know for certain that it fed on
fishes, this conclusion is confirmed, for fishes are not easily caught
now, and most probably were not easily caught ages ago.
The personal history of the fish-lizard, merely as a fossil or
"remain," is interesting; so much so, that we may perhaps be allowed
to relate the circumstances of his _début_ before the scientific
world, in the days of the ever-illustrious Cuvier, to whom we have
already alluded. But England had its share of illustrious men, too,
though lesser lights compared to the founder of comparative
anatomy,--such as Sir Richard Owen, on whom the mantle of his friend
Cuvier has fallen; Conybeare, De la Beche, and Dean Buckland.
These scientific men, aided by the untiring labours of many
enthusiastic collectors of organic remains, have been the means of
solving the riddle of the fish-lizard, and of introducing him to the
public. By this time there is, perhaps, no creature among the host of
Antediluvian types better known than this reptile.
The remains of fish-lizards have attracted the attention of collectors
and describers of fossils for nearly two centuries past. The vertebræ,
or "cup-bones," as they are often called, of which the spinal column
was composed, were figured by Scheüchzer, in an old work entitled
_Querelæ Piscium_; and, at that time, they were supposed to be the
vertebræ of fishes. In the year 1814 Sir Everard Home described the
fossil remains of this creature, in a paper read before the Royal
Society, and published in their _Philosophical Transactions_. This
fossil was first discovered in the Lias strata of the Dorsetshire
coast. Other papers followed till the year 1820. We are chiefly
indebted to De la Beche and Conybeare for pointing out and
illustrating the nature of the fish-lizard; and that at a time when
the materials for so doing were far more scanty than they are now. Mr.
Charles König, Mr. Thomas Hawkins, Dean Buckland, Sir Philip Egerton,
and Professor Owen have all helped to throw light on the structure and
habits of these old tyrants of the seas of that age, which is known as
the Jurassic period. They lived on, however, to the succeeding or
Cretaceous period, during which our English chalk was forming; but the
Liassic age was the one in which they flourished most abundantly, and
developed the greatest variety.
In the year 1814 a few bones were found on the Dorsetshire coast
between Charmouth and Lyme-Regis, and added to the collection of
Bullock. They came from the Lias cliffs, undermined by the encroaching
sea. Sir Everard's attention being attracted to them, he published the
notices already referred to. The analogy of some of the bones to those
of a crocodile, induced Mr. König, of the British Museum, to believe
the animal to have been a saurian, or lizard; but the vertebræ, and
also the position of certain openings in the skull, indicated some
remote affinity with fishes, but this must not be pressed too far. The
choice of a name, therefore, involved much difficulty; and at length
he decided to call it the _Ichthyosaurus_, or fish-lizard. Mr.
Johnson, of Bristol, who had collected for many years in that
neighbourhood, found out some valuable particulars about these
remains. The conclusions of Dean Buckland, then Professor of Geology
at Oxford, led Sir Everard to abandon many of his former conclusions.
The labours of the learned men of the day were greatly assisted by the
exertions of Miss Anning, an enthusiastic collector of fossils. This
lady, devoting herself to science, explored the frowning and
precipitous cliffs in the neighbourhood of Lyme-Regis, when the
furious spring-tide combined with the tempest to overthrow them, and
rescued from destruction by the sea, sometimes at the peril of her
life, the few specimens which originated all the facts and
speculations of those persons whose names will ever be remembered with
gratitude by geologists.
[Illustration: Fig. 3.--_Ichthyosaurus intermedius._]
Probably our readers are already more or less familiar with the
drawings of the fossilised remains of Ichthyosauri to be seen in
almost every text-book of geology. (Fig. 3 is from Owen's _British
Fossil Reptiles_.) But we recommend all who take an interest in the
world's lost creations to pay a visit to the great Natural History
Museum, at South Kensington. The fossil reptile gallery contains a
magnificent series of Ichthyosauri, about thirty in number. Of these a
large number were obtained through the exertions of the late Mr. T.
Hawkins, a Somersetshire gentleman, who was a most ardent collector of
fossil reptiles, and who devoted himself with great enthusiasm and
unsparing energy to the acquisition of a truly splendid collection of
these most interesting relics of the past. Nearly sixty years ago he
arranged for the purchase of his treasures by the authorities of the
British Museum, and thus his collection became the property of the
nation.
His specimens were figured and described by him in two large folio
volumes. The first was published in 1834, under the title, _Memoirs of
the Ichthyosauri and Plesiosauri_; his second, with the same plates,
in 1842, under the quaint title of _The Book of the Great
Sea-Dragons_. The large lithographic drawings of his fine specimens
were beautifully executed by Scharf and O'Neil. The plates are the
only really valuable part of these two curious and ill-written books.
His descriptions are not of much value, and his pages are encumbered
with a vast amount of extraneous matter. The author is immensely proud
of his collection, and his vanity is conspicuous throughout. Instead
of confining himself to descriptions of what he found, and how he
found them, he continually wanders into all sorts of subjects that
are, to say the least, irrelevant. In one place he introduces ancient
history and mythology; in another, Old Testament chronology; in
another, the unbelieving spirit of the age; and here and there
indulges in vague unphilosophical speculations. Altogether his two
volumes are a curious mixture of bigotry, conceit, and unrestrained
fancy, and they afforded to the present writer no small amusement. One
rises from the perusal of such men's writings with a strong sense of
the contrast between the humble and patient spirit in which our great
men of to-day, such as Professor Owen, study nature and record their
observations, and the vague, conceited outpourings of some
old-fashioned writers.
Mr. Hawkins tells us that his youthful attention was directed to the
Lias quarries, near Edgarly, in Somersetshire, in consequence of some
strange reports. It was said that the bones of giants and infants had,
at distant intervals, been found in them. These quarries he visited,
and, by offers of generous payment, induced the workmen to keep for
him all the remains they might find. In this way he finally obtained
the co-operation of all the quarrymen in the county.
[Illustration: Plate II.
FISH-LIZARDS.
_Ichthyosaurus communis._ _Ichthyosaurus tenuirostris._
Length about 22 feet. Fishes, _Dapedius_, etc. A smaller species.]
Mr. Hawkins thus expresses his delight on obtaining an Ichthyosaurus
which was pointed out to him by Miss Anning, near the church at
Lyme-Regis, in the year 1832: "Who can describe my transport at the
sight of the colossus? My eyes the first which beheld it! Who shall
ever see them lit up with the same unmitigated enthusiasm again? And I
verily believe that the uncultivated bosoms of the working men were
seized with the same contagious feeling; for they and the surrounding
spectators waved their hats to an 'Hurra!' that made hill and mossy
dell echoing ring."
This specimen, however, got sadly broken in its fall from the cliff;
but in time he put all the pieces together again. Speaking of his own
collection, he says, "This stupendous treasure was gathered by me from
every part of England; arranged, and its multifarious features
elaborated from the hard limestone by my own hands. A tyro in
collecting at the age of twelve years, I then boasted of all the
antiquities that were come-at-able in my neighbourhood, but, finding
that everybody beat my cabinet of coins, I addressed myself to
worm-eaten books, and last to fossils." Before he was twenty years of
age he had obtained a very fine collection of organic remains.
When, however, he complains of the Philistine dulness and stupidity of
quarrymen, who often, in their ignorance, break up finds of almost
priceless value, we can fully sympathize.
In general contour the body of the fish-lizard was long and tapering,
like that of a whale (see Plate II.). It probably showed no distinct
neck. The long tail was its chief organ of propulsion. We notice two
pairs of fins, or paddles; one on the fore part of the body, the other
on the hinder part, like the pectoral and abdominal fins of a fish.
The skin was scaleless and smooth, or slightly wrinkled, like that of
a whale. No traces of scales have ever been found; and if such had
existed, they would certainly have been preserved, since those of
fishes and crocodiles of the Jurassic period have been found in
considerable number and variety. It is therefore safe to conclude that
such were absent in this case. In the Lias strata, at least, the
specimens are often preserved with most wonderful completeness (see p.
47).
The long and pointed jaws are a striking feature of these animals. The
eyes were very large and powerful, and specially adapted, as we shall
see presently, to the conditions of their life.
It might, perhaps, be asked whether the fish-lizards breathed, like
fishes, by means of gills. That question can easily be answered; for
if they had possessed gills for taking in water and breathing the air
dissolved therein, they would reveal the fact by showing a bony
framework for the support of gills, such as are to be found in all
fishes. These structures, known as "branchial arches," are absent;
therefore the fish-lizards possessed lungs, and breathed air like
reptiles of the present day. Their skulls show where the nostrils were
situated; namely, near the eyes, and not at the end of the upper
jaw-bone. There are also passages in the skull leading from the
nostrils to the palate, along which currents of air passed on their
way to the lungs. Being air-breathers, they would be compelled
occasionally to seek the surface of the sea, in order to obtain a
fresh supply of the life-giving element--oxygen; but, being
cold-blooded and with a small brain, needing a much less supply of
oxygen for its work, the fish-lizards had, like fishes, this advantage
over whales, which are warm-blooded--that their stern-propeller, or
tail-fin, could take the form best adapted for a swift,
straight-forward course through the water.
In the whale tribe the tail-fin is horizontal; and this is so on
account of their need, as large-brained, warm-blooded air-breathers,
of speedy access to the atmospheric air. Were it otherwise, they would
not have the means of rising with sufficient rapidity to the surface
of the sea; for they have only one pair of fins. But the fish-lizards
had two pairs of these appendages, and the hinder or pelvic pair no
doubt were of great service in helping the creatures to come up to the
surface when necessary.
Thus we see that the whale, with its one pair of paddles, has a tail
specially planned with a view to rapid vertical movement through the
water; while in the fish-lizards, who did not require to breathe so
frequently, the tail-fin was planned with a view to swift and straight
movement forward as they pursued their prey, and they were compensated
by having bestowed upon them an extra pair of paddles. Thus we learn
how one part of an animal is related to and dependent upon another,
and how they all work together with the greatest harmony for certain
definite purposes (see p. 6).
[Illustration: Fig. 4.--(A) Lateral and (B) profile views of a tooth
of _Ichthyosaurus platyodon_ (Conybeare), Lower Lias, Lyme Regis,
Dorsetshire, (C) Tooth of _Ichthyosaurus communis_ (Conybeare), Lower
Lias, Lyme Regis, Dorset.]
These great marine predaceous reptiles literally swarmed in the seas
of the Lias period, and no doubt devoured immense shoals of the
fishes of those times, whose numbers were thus to some extent kept
down. There is clear proof of this in the fossilised droppings--known
as "coprolites,"--which show on examination the broken and comminuted
remains of the little bony plates of ganoid fishes that we know were
contemporaries of these reptiles. Probably young ones were sometimes
devoured too.
It was in the period of the Lias that fish-lizards attained to their
greatest development, both in numbers and variety; and the strata of
that period have preserved some interesting variations. It will be
sufficient here to point out two, namely, Ichthyosaurus
tenuirostris--an elegant little form, in which the jaws, instead of
being massive and strong, were long and slender like a bird's beak;
and also Ichthyosaurus latifrons (Fig. 5), with jaws still more
bird-like. Our artist has attempted to show the former variety in our
illustration (Plate II.). A most perfect example of this pretty little
Ichthyosaur, from the Lower Lias of Street in Somerset, has recently
been presented to the National Collection at South Kensington by Mr.
Alfred Gillett, of Street, and may be seen there. In this group of
fish-lizards the eyes are relatively larger, and we should imagine
that they were very quick in detecting and catching their prey; their
paddles also have larger bones.
[Illustration: Fig. 5.--Skull of _Ichthyosaurus latifrons_.]
There is a remarkably fine specimen at Burlington House, in the rooms
of the Geological Society, of an Ichthyosaurus' head, which the writer
found, on measuring, to be about five feet six inches long. A cast of
this head is exhibited at South Kensington. The largest of the
specimens in the National Collection is twenty-two feet long and eight
feet across the expanded paddles; but it is known that many attained
much greater dimensions. Judging from detached heads and parts of
skeletons, it is probable that some of them were between thirty and
forty feet long. A specimen of Ichthyosaurus platyodon in the
collection of the late Mr. Johnson, of Bristol, has an eye-cavity with
a diameter of fourteen inches. This collection is now dispersed.
With regard to their habits, Sir Richard Owen concludes that they
occasionally sought the shores, crawled on the strand, and basked in
the sunshine. His reason for this conjecture (which, however, is not
confirmed by Dr. Fraas's recent discoveries) is to be found in the
bony structure connected with the fore-paddles, which is not to be
found in any porpoise, dolphin, grampus, or whale, and for want of
which these creatures are so helpless when left high and dry on the
shore.[7] The structure in question is a strong bony arch, inverted
and spanning across beneath the chest from one shoulder to the other.
A fish-lizard, when so visiting the shore for sleep, or in the
breeding season, would lie or crawl, prostrate, with its under side
resting or dragging on the ground--somewhat after the manner of a
turtle.
[7] It is, perhaps, hardly necessary to remark that whales are not
fishes, but mammals which have undergone great change in order to
adapt themselves to a marine life. Their hind limbs have practically
vanished, only a rudiment of them being left.
It is a curious fact that this bony arch resembles the same part in
those singular and problematical mammals, the Echidna and the
Platypus, or duck-mole.
The enormous magnitude and peculiar construction of the eye are highly
interesting features. The expanded pupil must have allowed of the
admittance of a large quantity of light, so that the creature
possessed great powers of vision.
The organic remains associated with fish-lizards tell us that they
inhabited waters of moderate depth, such as prevails near a coast-line
or among coral islands. Moreover, an air-breathing creature would
obviously be unable to live in "the depths of the sea;" for it would
take a long time to get to the surface for a fresh supply of air.
Perhaps no part of the skeleton is more interesting than the curious
circular series of bony plates surrounding the iris and pupil of the
eye. The eyes of many fishes are defended by a bony covering
consisting of two pieces; but a circle of bony overlapping plates is
now only found in the eyes of turtles, tortoises, lizards, and birds,
and some alligators. This elaborate apparatus must have been of some
special use; the question is--What service or services did it perform?
Here, again, we find answers suggested by Owen and Buckland. It would
aid, they say, in protecting the eye-ball from the waves of the sea
when the creature rose to the surface, as well as from the pressure of
the water when it dived down to the bottom--for even at a slight depth
pressure increases, as divers know. But it appears that the ring of
bony plates fulfilled a yet more important office, thereby enabling
the fish-lizards to play admirably their part in the world in which
they lived, and to succeed in the struggle of life; for even in those
remote days there must have been, as now, a keen competition among all
animals, so that the victory was to those that were best equipped.
Would it not be an advantage for them to have the power of seeing
their finny prey whether near or far? Certainly it would; and so we
are told that, by bringing the plates a little nearer together, and
causing them to press gently on the eye-ball, so as to make the eye
more convex--that is, bulging out--a nearer object would be the better
discerned. On the other hand, by relaxing this pressure, thus
enlarging the aperture of the pupil and diminishing the convexity, a
distant object would be focussed upon the retina. In this manner some
birds alter the focus of their eyes while swooping down on their prey.
What a wonderful arrangement! We often hear of people having two pairs
of spectacles--with lenses of different curvature--one for reading,
and the other for seeing more distant objects than a book held in the
hand. But here is a creature that possessed an apparatus far more
simple and effective than that supplied by the optician! Dr. Buckland,
speaking of these "sclerotic plates," as they are called, says they
show "that the enormous eye of which they formed the front was an
optical instrument of varied and prodigious power, enabling the
Ichthyosaurus to descry its prey in the obscurity of night and in the
depths of the sea." But the last expression must be taken in a limited
sense (see Fig. 6).
[Illustration: Fig. 6.--Head of _Ichthyosaurus platyodon_.]
It might well be supposed that no record had been preserved from which
we could learn anything about the nature of the skin of our
fish-lizard; but even this wish has been partly fulfilled, to the
delight of all geologists. Certain specimens have been obtained, from
the Lias of England and Germany, that show faithful impressions of the
skin that covered the paddles. A specimen of this nature has lately
been presented to the national treasure-house at South Kensington by
Mr. Montague Brown. On the inner side of the paddle was a broad
fin-like expansion, admirably adapted to obtain the full advantage of
the stroke of the limb in swimming.[8]
[8] Mr. Smith Woodward informs the writer that specimens have lately
been found near Würtemberg, with evidence of a triangular fin on the
back. Plate II. has been redrawn for this edition, to make it more in
harmony with Dr. Fraas's discoveries. (See Appendix V.)
Speaking of the limbs, it should be mentioned that the bones of each
finger, instead of being elongated and limited in number to three in
each of the five fingers, are polygonal in shape and arranged in as
many as seven or eight rows, while those of each finger are
exceedingly numerous. Thus the whole structure forms a kind of bony
pavement which must have been very supple. Such a limb would be one of
the most efficient and powerful swimming organs known in the whole
animal kingdom. In whales the fingers of the flippers are of the usual
number, namely, five. Some species of fish-lizards had as many as over
a hundred separate little bones in the fore-paddle.
Another question naturally suggests itself: Were they viviparous, or
did they lay eggs like crocodiles? This question seems to have been
answered in favour of the first supposition; and in the following
interesting manner. It not infrequently happens that entire little
skeletons of very small individuals are found under the ribs of large
ones. They are invariably uninjured, and of the same species as the
one that encloses them, and with the head pointing in one direction.
Such specimens are most probably the fossilised remains of little
fish-lizards, that were yet unborn when their mothers met with an
untimely end (see p. 51). In some cases, however, they may be young
ones that were swallowed. (See Appendix V.)
The jaws of these hungry formidable monsters were provided with a
series of formidable teeth--sometimes over two hundred in
number--inserted in a long groove, and not in distinct sockets, as in
the case of crocodiles. In some cases, sixty or more have been found
on each side of the upper and lower jaws, giving a total of over two
hundred and forty teeth! The larger teeth may be two inches or more in
length.
The jaws were admirably constructed on a plan that combined lightness,
elasticity, and strength. Instead of consisting of one piece only,
they show a union of plates of bone, as in recent crocodiles. These
plates are strongest and most numerous just where the greatest
strength was wanted, and thinner and fewer towards the extremities of
the jaw. A crocodile, Sir Samuel Baker says, in his _Wild Beasts and
their Ways_, can bite a man in two; and no doubt our fish-lizard
would have been glad to perform the same feat! But in his pre-Adamite
days the opportunity did not present itself.
The spinal column, or backbone, with its generally concave vertebræ,
must have been highly flexible, as is that of a fish, especially the
long tail which the creature worked rapidly from side to side as it
lashed the waters.
The hollows of these concave vertebræ must have been originally filled
up with fluid forming an elastic bag, or capsule. To get a clearer
idea of this, take a small portion of the backbone of a boiled cod, or
other "bony" fish, and you will see on pulling it to pieces, the
white, jelly-like substance that fills up the hollows between the
vertebræ. In this way Nature provides a soft cushion between the
joints, that allows of a certain amount of movement, while, at the
same time, the column holds together. The backbone of a fish may not
inaptly be compared to a railway train. Each of the carriages
represents a vertebra, and the buffers act as cushions when the train
is bent in running round a curve. After all, we must learn from
Nature; and many of the greatest mechanical and engineering triumphs
of to-day are based upon the methods used by Nature in the building up
and equipment of vegetable and animal forms of life.
It may, perhaps, be inquired whether there is any evidence for the
existence of a tail-fin, such as is shown in our illustration. To this
it may be replied that the presence of such an appendage is as good as
proved by a certain flattening of the vertebræ at the end of the tail,
detected by Owen. The direction of this flattening is from side to
side, and therefore the tail-fin must have been vertical, like that of
a fish. In one specimen Sir Richard Owen has detected as many as 156
vertebræ to the whole body.
Our description of the fish-lizard has, we trust, been
sufficient--although not couched in the language used by men of
science--to give a fair idea of its structure and habits.
In conclusion, a few words may be said about the ancestry and
life-history of these ancient monsters. Palæontologists have good
reason to believe that they were descended from some early form of
land reptile. If so, they show that whales are not the first land
animals that have gone back to the sea, from which so many forms of
life have taken their rise.
During the long Mesozoic period fish-lizards played the part that
whales now play in the economy of the world; and they resembled the
latter, not only in general shape, but in the situation of the
nostrils (near the eye), and in their teeth and long jaws. But these
curious resemblances must not be interpreted to mean that whales and
fish-lizards are related to each other. They only show that similar
modes of life tend to produce artificial resemblances--just as some
whales, in their turn, show a superficial resemblance to fishes.
With regard to the particular form of reptile from which the
fish-lizard may have been derived, no certain conclusion has at
present been arrived at. This is chiefly from want of fuller knowledge
of early forms, such as may have existed in the previous periods known
as the Carboniferous and Trias (see Appendix I.). But there are
certain features in the skulls, teeth, and vertebræ that suggest a
relationship with the Labyrinthodonts, or primæval salamanders that
flourished during the above periods, or at least from amphibians more
or less closely allied to them. They cannot by any possibility be
regarded as modified fishes; for fishes have gills instead of lungs.
The fish-lizards played their part, and played it admirably; but their
days were numbered, and the place they occupied has since been taken
by a higher type--the mammal. As reptiles, they were eminently a
success; but, then, they were only reptiles, and therefore were at
last left behind in the struggle for existence, until finally they
died out, at the end of the Cretaceous period, when certain important
geographical and other changes took place, helping to cause the
extinction of many other strange forms of life, as we shall see later
on (see p. 147).
They had a wide geographical range; for their remains have been
discovered in Arctic regions, in Europe, India, Ceram, North America,
the east coast of Africa, Australia, and New Zealand.
In American deposits they are represented by certain toothless forms,
to which the name Sauranodon ("toothless lizard") has been given.
These have been discovered by Professor Marsh, in the Jurassic strata
of the Rocky Mountains. They were eight or nine feet long, and in
every other respect resembled Ichthyosaurs. As we have endeavoured to
indicate in our illustration, the fish-lizards flourished in seas
wherein animal, and doubtless vegetable life was very abundant. Any
one who has collected fossils from the Lias of England will have found
how full it is of beautiful organic remains, such as corals, mollusca,
encrinites, sea-urchins, and other echinoids, fishes, etc.
The climate of this period in Europe was mild and genial, or even
semi-tropical. Coral reefs and coral islands varied the landscape.
There is just one more point of interest that ought not to be omitted;
it refers to the manner in which these reptiles of the Lias age met
their deaths, and were thus buried up in their rocky tombs. Sir
Charles Lyell and other writers point out that the individuals found
in those strata must have met with a sudden death and quick burial;
for if their uncovered bodies had been left, even for a few hours,
exposed to putrification and the attacks of fishes at the bottom of
the sea, we should not now find their remains so completely preserved
that often scarcely a single bone has been moved from its right place.
What was the exact nature of this operation is at present a matter of
doubt.