Transcriber's Note
Whole and fractional parts of numbers are displayed as 5-1/2.
Text emphasis is denoted as follows: _Italic_ and =Bold=.
EXTINCT MONSTERS.
[Illustration: Plate XI.
A GIGANTIC HORNED DINOSAUR, TRICERATOPS PRORSUS.
Length about 25 feet.]
EXTINCT MONSTERS.
_A POPULAR ACCOUNT OF SOME OF THE LARGER
FORMS OF ANCIENT ANIMAL LIFE._
BY
REV. H. N. HUTCHINSON, B.A., F.G.S.,
AUTHOR OF "THE AUTOBIOGRAPHY OF THE EARTH,"
AND "THE STORY OF THE HILLS."
WITH ILLUSTRATIONS BY J. SMIT AND OTHERS.
_FIFTH AND CHEAPER EDITION._
LONDON: CHAPMAN & HALL, LD.
1897.
_All rights reserved._
"The possibilities of existence run so deeply into the
extravagant that there is scarcely any conception too
extraordinary for Nature to realise."--Agassiz.
PREFACE BY DR. HENRY WOODWARD, F.R.S.
KEEPER OF GEOLOGY, NATURAL HISTORY MUSEUM.
I have been requested by my friend Mr. Hutchinson, to express my
opinion upon the series of drawings which have been prepared by that
excellent artist of animals, Mr. Smit, for this little book entitled
"Extinct Monsters."
Many of the stories told in early days, of Giants and Dragons, may
have originated in the discovery of the limb-bones of the Mammoth, the
Rhinoceros, or other large animals, in caves, associated with heaps of
broken fragments, in which latter the ignorant peasant saw in fancy
the remains of the victims devoured at the monster's repasts.
In Louis Figuier's _World before the Deluge_ we are favoured with
several highly sensational views of extinct monsters; whilst the pen
of Dr. Kinns has furnished valuable information as to the "slimy"
nature of their blood!
The late Mr. G. Waterhouse Hawkins (formerly a lithographic artist)
was for years occupied in unauthorised restorations of various
Secondary reptiles and Tertiary mammals, and about 1853 he received
encouragement from Professor Owen to undertake the restorations of
extinct animals which still adorn the lower grounds of the Crystal
Palace at Sydenham.
But the discoveries of later years have shown that the Dicynodon and
Labyrinthodon, instead of being toad-like in form, were lacertilian or
salamander-like reptiles, with elongated bodies and moderately long
tails; that the Iguanodon did not usually stand upon "all-fours," but
more frequently sat up like some huge kangaroo with short fore limbs;
that the horn on its snout was really on its wrist; that the
Megalosaurus, with a more slender form of skeleton, had a somewhat
similar erect attitude, and the habit, perhaps, of springing upon its
prey, holding it with its powerful clawed hands, and tearing it with
its formidable carnivorous teeth.
Although the Bernissart Iguanodon has been to us a complete revelation
of what a Dinosaur really looked like, it is to America, and chiefly
to the discoveries of Marsh, that we owe the knowledge of a whole
series of new reptiles and mammals, many of which will be found
illustrated within these pages.
Of long and short-tailed Pterodactyles we now know almost complete
skeletons and details of their patagia or flying membranes. The
discovery of the long-tailed feathered bird with teeth--the
Archæopteryx, from the Oolite of Solenhofen, is another marvellous
addition to our knowledge; whilst Marsh's great Hesperornis, a
wingless diving bird with teeth, and his flying toothed bird, the
Ichthyornis dispar, are to us equally surprising.
Certainly, both in singular forms of fossil reptilia and in early
mammals, North America carries off the palm.
Of these the most remarkable are Marsh's Stegosaurus, a huge torpid
reptile, with very small head and teeth, about twenty feet in length,
and having a series of flattened dorsal spines, nearly a yard in
height, fixed upon the median line of its back; and his Triceratops,
another reptile bigger than Stegosaurus, having a huge neck-shield
joined to its skull, and horns on its head and snout. Nor do the
Eocene mammals fall short of the marvellous, for in Dinoceras we find
a beast with six horns, and sword-bayonet tusks, joined to a skeleton
like an elephant.
Latest amongst the marvels in modern palæontological discovery has
been that made by Professor Fraas of the outline of the skin and fins
in Ichthyosaurus tenuirostris, which shows it to have been a veritable
shark-like reptile, with a high dorsal fin and broad fish-tail, so
that "fish-lizard" is more than ever an appropriate term for these old
Liassic marine reptiles.
As every palæontologist is well aware, restorations are ever liable to
emendation, and that the present and latest book of extinct monsters
will certainly prove no exception to the rule is beyond a doubt, but
the author deserves our praise for the very boldness of his attempt,
and the honesty with which he has tried to follow nature and avoid
exaggeration. Every one will admire the simple and unaffected style in
which the author has endeavoured to tell his story, avoiding, as far
as possible, all scientific terms, so as to bring it within the
intelligence of the unlearned. He has, moreover, taken infinite pains
to study up his subject with care, and to consult all the literature
bearing upon it. He has thus been enabled to convey accurate
information in a simple and pleasing form, and to guide the artist in
his difficult task with much wisdom and intelligence. That the
excellence of the sketches is due to the artist, Mr. Smit, is a
matter of course, and so is the blame, where criticism is legitimate;
and no one is more sensible of the difficulties of the task than Mr.
Smit himself.
Speaking for myself, I am _very well pleased_ with the series of
sketches; and I may say so with the greater ease and freedom from
responsibility, as I have had very little to do with them, save in one
or two trifling matters of criticism. I may venture, however, to
commend them to my friends among the public at large as the happiest
set of restorations that has yet appeared.
H. W.
[Illustration: Plate XXIV.
THE LATE SIR RICHARD OWEN AND A SKELETON OF DINORNIS MAXIMUS.
(_From a photograph._)]
AUTHOR'S PREFACE.
Natural history is deservedly a popular subject. The manifestations of
life in all its varied forms is a theme that has never failed to
attract all who are not destitute of intelligence. From the days of
the primitive cave-dwellers of Europe, who lived with mammoths and
other animals now lost to the world; of the ancient Egyptians, who
drew and painted on the walls of their magnificent tombs the creatures
inhabiting the delta of the Nile; of the Greeks, looking out on the
world with their bright and child-like curiosity, down to our own
times, this old, yet ever new, theme has never failed. Never before
was there such a profusion of books describing the various forms of
life inhabiting the different countries of the globe, or the rivers,
lakes, and seas that diversify its scenery. Popular writers have done
good service in making the way plain for those who wish to acquaint
themselves with the structures, habits, and histories of living
animals; while for students a still greater supply of excellent
manuals and text-books has been, and still continues to be,
forthcoming.
But in our admiration for the present we forget the great past. How
seldom do we think of that innumerable host of creatures that once
trod this earth! How little in comparison has been done for _them_!
Our natural-history books deal only with those that are alive now. Few
popular writers have attempted to depict, as on a canvas, the great
earth-drama that has, from age to age, been enacted on the terrestrial
stage, of which we behold the latest, but probably not the closing
scenes.
When our poet wrote "All the world's a stage," he thought only of "men
and women," whom he called "merely players," but the geologist sees a
wider application of these words, as he reviews the drama of past life
on the globe, and finds that animals, too, have had "their exits and
their entrances;" nay more, "the strange eventful history" of a human
life, sketched by the master-hand, might well be chosen to illustrate
the birth and growth of the tree of life, the development of which we
shall briefly trace from time to time, as we proceed on our survey of
the larger and more wonderful animals of life that flourished in
bygone times.
We might even make out a "seven ages" of the world, in each of which
some peculiar form of life stood out prominently, but such a scheme
would be artificial.
There is a wealth of material for reconstructing the past that is
simply bewildering; and yet little has been done to bring before the
public the strange creatures that have perished.[1]
[1] Figuier's _World before the Deluge_ is hardly a trustworthy book,
and is often not up to date. The restorations also are misleading.
Professor Dawson's _Story of the Earth and Man_ is better; but the
illustrations are poor. Nicholson's _Life-History of the Earth_ is a
student's book. Messrs. Cassells' _Our Earth and its Story_ deals with
the whole of geology, and so is too diffusive; its ideal landscapes
To the writer it is a matter of astonishment that the
and restorations leave much to be desired.
discoveries of Marsh, Cope, Leidy, and others in America, not to
mention some important European discoveries, should have attracted so
little notice in this country. In the far and wild West a host of
strange reptiles and quadrupeds have been unearthed from their rocky
sepulchres, often of incredibly huge proportions, and, in many cases,
more weird and strange than the imagination could conceive; and yet
the public have never heard of these discoveries, by the side of which
the now well-known "lost creations" of Cuvier, Buckland, or Conybeare
sink into the shade. For once, we beg leave to suggest, the hungry
pressman, seeking "copy," has failed to see a good thing. Descriptions
of some of "Marsh's monsters" and how they were found, might, one
would think, have proved attractive to a public ever on the look out
for something new.
Professor Huxley, comparing our present knowledge of the mammals of
the Tertiary era with that of 1859, states that the discoveries of
Gaudry, Marsh, and Filhol, are "as if zoologists were to become
acquainted with a country hitherto unknown, as rich in novel forms of
life as Brazil or South America once were to Europeans."
The object of this book is to describe some of the larger and more
monstrous forms of the past--the lost creations of the old world; to
clothe their dry bones with flesh, and suggest for them backgrounds
such as are indicated by the discoveries of geology: in other words,
to endeavour, by means of pen and pencil, to bring them back to life.
The ordinary public cannot learn much by merely gazing at skeletons
set up in museums. One longs to cover their nakedness with flesh and
skin, and to see them as they were when they walked this earth.
Our present imperfect knowledge renders it difficult in some cases to
construct successful restorations; but, nevertheless, the attempt is
worth making: and if some who think geology a very dry subject, can be
converted to a different opinion on reading these pages, we shall be
well rewarded for our trouble.
We venture to hope that those who will take the trouble to peruse this
book, or even to look at its pictures, on which much labour and
thought have been expended, will find pleasure in visiting the
splendid geological collection at Cromwell Road. We have often watched
visitors walking somewhat aimlessly among those relics of a former
world, and wished that we could be of some service. But, if this
little book should help them the better to understand what they see
there, our wish will be accomplished.
Another object which the writer has kept in view is to connect the
past with the present. It cannot be too strongly urged that the best
commentary on the dead past is the living present. It is unfortunate
that there is still too great a tendency to separate, as by a great
gulf, the dead from the living, the past from the present, forms of
life. The result of this is seen in our museums. Fossils have too
often been left to the attention of geologists not always well
acquainted with the structures of living animals. The more frequent
introduction of fossil specimens side by side with modern forms of
life would not only be a gain to the progress and spread of geological
science, but would be a great help to students of anatomy and natural
history. The tree of life is but a mutilated thing, and half its
interest is gone, when the dead branches are lopped off.
It is, perhaps, justifiable to give to the term "monster" a somewhat
extended meaning. The writer has therefore included in his menagerie
of extinct animals one or two creatures which, though not of any great
size, are nevertheless remarkable in various ways--such, for instance,
as the winged reptiles, and anomalous birds with teeth, of later
times, and others. Compared with living forms, these creatures appear
to us as "monstrosities," and may well find a place in our collection.
The author wishes, in a few words, to thank those friends who have
rendered him assistance in his task.
Dr. Henry Woodward, F.R.S., Keeper of Geology, Natural History Museum,
has from the first taken a lively interest in this little book. He
kindly helped the author with his advice on difficult matters,
criticising some of the artist's preliminary sketches and suggesting
improvements in the restorations. With unfailing courtesy he has ever
been willing, in spite of many demands on his time, to place his
knowledge at the disposal of both the author and artist; and in this
way certain errors have been avoided. Besides this, he took the
trouble to read through the proof-sheets, and made suggestions and
corrections which have greatly improved the text. For all this welcome
aid the author begs to return his sincere thanks.
To Mr. Smith Woodward, of the Natural History Museum, the author is
also much indebted for his kindness in reading through the text and
giving valuable information with regard to the latest discoveries.
The artist, Mr. Smit, notwithstanding the novelty of the subject and
the difficulties of the task, has thrown himself heartily into the
work of making the twenty-four restorations of extinct animals. To
him, also, the author is greatly indebted, and considers himself
fortunate in having secured the services of so excellent an artist.
To the publishers his thanks are due for their liberality in the
matter of illustrations, and the readiness with which they have
responded to suggestions.
With regard to minor illustrations the following acknowledgments are
due:--
To the Palæontological Society of Great Britain for permission to
reproduce three of the illustrations in Sir Richard Owen's great work,
_British Fossil Reptiles_, published in their yearly volumes, viz.
Figs. 3, 4, and 8.
To Messrs. Bell and Co. for the following cuts from the late Dr.
Gideon A. Mantell's works: viz. Figs. 12, 14, 20, 33, 37, 38.
To Messrs. A. and C. Black for the following cuts from Owen's
_Palæontology_: viz. Figs. 51, 54, 56, 57.
* * * * *
Appendix IV. contains a list of some of the works of which the writer
has made use; but it would be impossible within reasonable limits to
enumerate all the separate papers which have necessarily been
consulted. The reader will find numerous references, such as "Case Y
on Plan," in brackets; these refer to the plan given at the end of the
excellent little _Guide to the Exhibition Galleries in the Department
of Geology and Palæontology in the Natural History Museum_, Cromwell
Road (price one shilling), which visitors to the Museum are advised to
obtain.
PREFACE TO SECOND EDITION.
The appearance of a second edition affords the author a pleasant
opportunity of thanking the reading public, and the Press, for the
kind way in which his endeavour to popularise the results of modern
Palæontology has been received. There seem to be fashions in all
things--even in sciences; and perhaps the wonderful advances we have
witnessed of late years in the physical sciences on the one hand, and
in biological sciences on the other, may have tended to throw
Palæontology somewhat into the shade. Let us hope that it will not
remain there long.
A large number of illustrations have been added for the present
edition, besides additional matter here and there in the text. Three
of the plates (viz. Plates II. X. XV.) have been redrawn. Plate II.
shows the Ichthyosaurus as interpreted by the latest discovery from
Würtemberg. Plate X. gives a somewhat different interpretation of the
Stegosaurus, suggested by some remarks of Mr. Lydekker.
A slight change will be noticed in Plate XV. (Brontops). Plate XVII.
is a great improvement on the old drawing (Fig. 28, old edition) of
the Megatherium skeleton. Plate XXIV., besides containing a valuable
portrait of the late Sir Richard Owen, gives another drawing of the
Dinornis skeleton.
_April, 1893._
CONTENTS.
PAGE
Preface by Dr. Henry Woodward v
Author's Preface ix
Preface to Second Edition xv
Introduction 1
CHAPTER I. How Extinct Monsters are preserved 9
CHAPTER II. Sea-scorpions 24
CHAPTER III. The Great Fish-lizards 34
CHAPTER IV. The Great Sea-lizards and their Allies 52
CHAPTER V. The Dragons of Old Time--Dinosaurs 61
CHAPTER VI. The Dragons of Old Time--Dinosaurs 75
CHAPTER VII. The Dragons of Old Time--Dinosaurs 98
CHAPTER VIII. Flying Dragons 121
CHAPTER IX. Sea-serpents 133
CHAPTER X. Some American Monsters 148
CHAPTER XI. Some Indian Monsters 162
CHAPTER XII. Giant Sloths and Armadillos 177
CHAPTER XIII. The Mammoth 192
CHAPTER XIV. The Mastodon and the Woolly Rhinoceros 217
CHAPTER XV. Giant Birds 227
CHAPTER XVI. The Great Irish Deer and Steller's Sea-cow 240
APPENDICES.
I.--Table of Stratified Rocks 251
II.--The Great Sea-serpent 253
III.--List of British Localities where Remains of the
Mammoth have been discovered 258
IV.--Literature 261
V.--Ichthyosaurs 264
INDEX 267
LIST OF FULL-PAGE ILLUSTRATIONS.
PLATE TO FACE PAGE
XI. A Gigantic Horned Dinosaur, Triceratops prorsus _Frontispiece_
XXIV. Sir Richard Owen and Skeleton of Dinornis maximus ix
I. Sea-scorpions 25
II. Fish-lizards 41
III. Pterodactyls--Long-necked Sea-lizard--Cuttle-fish
or Belemnite 55
IV. A Gigantic Dinosaur, Brontosaurus excelsus 69
V. Thigh-bone of the Largest of the Dinosaurs,
Atlantosaurus 71
VI. A Carnivorous Dinosaur, Megalosaurus Bucklandi 79
VII. A Gigantic Dinosaur, Iguanodon Bernissartensis 97
VIII. A Gigantic Dinosaur, Iguanodon Mantelli 101
IX. An Armoured Dinosaur, Scelidosaurus Harrisoni 105
X. A Gigantic Armoured Dinosaur, Stegosaurus ungulatus 113
XII. Group of Small Flying Dragons, or Pterodactyls 131
XIII. Group of Sea-serpents, Elasmosaur, and Fishes 141
XIV. A Large Extinct Mammal, Tinoceras ingens 151
XV. A Huge Extinct Mammal, Brontops robustus 161
XVI. A Gigantic Hoofed Mammal, Sivatherium giganteum 169
XVII. Skeleton of Great Ground Sloth of South America 179
XVIII. Great Ground Sloth of South America, Megatherium
americanum 181
XIX. A Gigantic Armadillo, Glyptodon asper 189
XX. The Mammoth, Elephas primigenius 205
XXI. The Mastodon of Ohio, M. americanus 219
XXII. The Woolly Rhinoceros, Rhinoceros tichorhinus 225
XXIII. Moa-birds 233
XXV. The Great Irish Deer, Cervus megaceros 243
XXVI. Steller's Sea-cow, Rhytina gigas 249
LIST OF FIGURES IN TEXT.
FIG. PAGE
1. Pterygotus anglicus 26
2. Silurian Merostomata 30
3. Ichthyosaurus intermedius 39
4. Teeth of Ichthyosauri 43
5. Skull of Ichthyosaurus latifrons 44
6. Skull of Ichthyosaurus platyodon 47
7. Mandibles of Long-necked Sea-Lizards 55
8. Skeleton of Plesiosaurus macrocephalus 56
9. Restored Skeleton of Brontosaurus excelsus 67
10. Neck Vertebræ of Brontosaurus 68
11. Head of Diplodocus 72
12. Lower Jaw-bone of Megalosaurus, with Teeth 77
13. Skeleton of Megalosaurus 78
14. Portion of a Slab of New Red Sandstone 80
15. Portion of a Slab, with Tracks 81
16. Limb-bones of Allosaurus 83
17. Skull of Ceratosaurus 84
18. Skull of Ceratosaurus nasicornis 85
19. Skeleton of Compsognathus longipes 86
20. Tooth of Iguanodon 88
21. Skeleton of Iguanodon Bernissartensis 100
22. Skull and Skeleton of Iguanodon Mantelli 101
23. Tracks of Iguanodon 102
24. Restored Skeleton of Scelidosaurus Harrisoni 105
25. Skeleton of Stegosaurus ungulatus 112
26. Tail Vertebræ of Stegosaurus 113
27. Limb-bones of Stegosaurus 114
28. Plates of Stegosaurus 115
29. Head of Triceratops 116
30. Skeleton of Triceratops prorsus 117
31. Bony Spines belonging to the Skin of Triceratops 119
32. Skeleton of Dimorphodon Macronyx 124
33. Skeleton of Scaphognathus crassirostris 125
34. Skeleton of Pterodactylus spectabilis 126
35. Skeleton of Rhamphorhynchus phyllurus 128
36. Skull of Pteranodon 129
37. Skull of Mosasaurus Hoffmanni 137
38. Teeth of Mosasaurus 137
39. Lower Tooth of Leiodon 138
40. Snout of Tylosaurus 143
41. Skeleton of Clidastes cineriarum 145
41a. Skull of Platecarpus 146
42. Skeleton of Tinoceras ingens 150
43. Skull of Dinoceras mirabile 151
44. Cast of Brain-cavity of Dinoceras mirabile 152
45. Skeleton of Brontops robustus 161
46. Skull of Sivatherium giganteum 168
47. Skeleton of Sivatherium giganteum 169
48. Restored Figure of Gigantic Tortoise,
Colossochelys atlas 171
49. The Elephant victorious over the Tortoise,
supporting the World, and unfolding the
Mysteries of the "Fauna Sivalensis" 173
50. Skeleton of Scelidotherium 184
51. Extinct Gigantic Armadillo, Glyptodon clavipes 190
52. Skeleton of Mammoth, Elephas primigenius 203
53. Figure of the Mammoth, engraved on Mammoth Ivory 214
54. Skeleton of Mastodon arvernensis 218
55. Head of Woolly Rhinoceros 224
56. Skeleton of the Elephant-footed Moa,
Dinornis elephantopus 233
57. Skeleton of Great Irish Deer, Cervus giganteus 242
58. Skeleton of Rhytina gigas 247
EXTINCT MONSTERS.
INTRODUCTION.
"The earth hath gathered to her breast again
And yet again, the millions that were born
Of her unnumbered, unremembered tribes."
Let us see if we can get some glimpses of the primæval inhabitants of
the world, that lived and died while as yet there were no men and
women having authority over the fishes of the sea and the fowls of the
air.
We shall, perhaps, find this antique world quite as strange as the
fairy-land of Grimm or Lewis Carroll. True, it was not inhabited by
"slithy toves" or "jabber-wocks," but by real beasts, of whose shapes,
sizes, and habits much is already known--a good deal more than might
at first be supposed. And yet, real as it all is, this antique
world--this panorama of scenes that have for ever passed away--is a
veritable fairy-land. In those days of which geologists tell us, the
principal parts were played, not by kings and queens, but by creatures
many of which were very unlike those we see around us now. And yet it
is no fairy-land after all, where impossible things happen, and where
impossible dragons figure largely; but only the same old world in
which you and I were born. Everything you will see here is quite true.
All these monsters once lived. Truth is stranger than fiction; and
perhaps we shall enjoy our visit to this fairy-land all the more for
that reason. For not even the dragons supposed to have been slain by
armed knights in old times, when people gave ear to any tale, however
extravagant, could equal in size or strength the real dragons we shall
presently meet with, whose actual bones may be seen in the Natural
History Museum at South Kensington.
Many people who visit this great museum and find their way to the
geological galleries on the right, pass hastily by the cases of bones,
teeth, and skeletons. These things, it seems, fail to interest them.
They do not know how to interpret them. They cannot picture to
themselves the kinds of creatures to which the relics once belonged;
and so they pass them by and presently go to the more attractive
collection of stuffed birds on the other side. There they see the
feathered tribes of the air all beautifully arranged; some poised in
the air by almost invisible wires; some perched on branches: but all
surrounded by grass, flowers, and natural objects, imitated with
marvellous reality, so that they see the birds as they really are in
nature, and can almost fancy they hear them singing.
Now, it has often occurred to the present writer that something more
might be done for the long-neglected "lost creations" of the world, to
bring them out of their obscurity, that they may be made to tell to
the passer-by their wondrous story. We can, however, well imagine some
of our readers asking, "Can these dry bones live?" "Yes," we would
say, "they can be made to live; reason and imagination will, if we
give them proper play, provide us eyes wherewith to see the world's
lost creations." To such men as Cuvier, Owen, Huxley, and others,
these dry bones _do_ live. It will be our object to describe to the
reader some of the wonderful results that have rewarded the lifelong
labours of such great men. We shall take some of the largest and
strangest forms of life that once lived, and try to picture them as
they really were when alive, whether walking on land, swimming in the
sea, or flying in the air; to understand the meanings of their more
obvious structures; and to form some conclusions with regard to their
habits, as well as to find out, if possible, their relations,--as far
as such questions have been answered by those most qualified to settle
these difficult matters.
All technical details, such as the general reader is unfamiliar with,
will be as far as possible suppressed. Let us fancy a long procession
of extinct monsters passing in single file before us, and ourselves
endeavouring to pick out their "points" as they present themselves to
the eye of imagination. It is not, be it remembered, mere imagination
that guides the man of science in such matters, for all his
conclusions are carefully based on reason; and when conclusions are
given, we shall endeavour to show how they have been arrived at.
For millions of years countless multitudes of living animals have
played their little parts on the earth and passed away, to be buried
up in the oozy beds of the seas of old time, or entombed with the
leaves that sank in the waters of primæval lakes. The majority of
these perished beyond all recovery, leaving not a trace behind; yet a
vast number of fossilised remains have been, in various ways,
preserved; sometimes almost as completely as if Dame Nature had
thoughtfully embalmed them for our instruction and delight.
Down in those old seas and lakes she kept her great museum, in order
to preserve for us a selection of her treasures. In course of time she
slowly raised up sea-beds and lake-bottoms to make them into dry land.
This museum is everywhere around us. We have but to enter quarries and
railway cuttings, or to search in coal-mines, or under cliffs at the
sea-side, and we can consult her records. As the ancient Egyptians
built tombs, pyramids, and temples, from which we may learn their
manner of life and partly read their history, so Nature has entombed,
not one race only, but many races of the children of life. Her
records are written in strange hieroglyphs, yet it is not difficult to
interpret their meaning; and thus many an old story, many an old
scene, may be pictured in the mind of man.
Shall we call this earth-drama a tragedy or a comedy? Doubtless tragic
scenes occurred at times; as, for instance, when fierce creatures
engaged in deadly combat: and probably amusing, if not comic,
incidents took place occasionally, such as might have provoked us to
laughter, had we been there to see them. But let us simply call it a
drama. Backgrounds of scenery were not wanting. Then, as now, the
surface of the earth was clothed with vegetation, and strange cattle
pastured on grassy plains. Vegetation was at times very luxuriant. The
forests of the coal period, with their giant reeds and club-moss
trees, must have made a strange picture. Then, as now, there rose up
from the plains lofty ranges of mountains, reaching to the clouds,
their summits clothed with the eternal snows. These, too, played their
part, feeding the streams and the rivers that meandered over the
plains, bringing life and fertility with them, as they do now. The sun
shone and the wind blew: sometimes gently, so that the leaves just
whispered in an evening breeze; at other times so violently that the
giants of the forest swayed to and fro, and the seas lashed themselves
furiously against rocky coasts. Nor were the underground forces of the
earth less active than they are now: volcanic eruptions often took
place on a magnificent scale; volcanoes poured out fiery lava streams
for leagues beneath their feet; great showers of ashes and fine dust
were ejected in the air, so that the sun was darkened for a time, and
the surface of the sea was covered for many miles with floating pumice
and volcanic dust, which in time sank to the bottom, and was made into
hard rock, such as we now find on the top of Snowdon.
Earthquake shocks were quite as frequent, and no doubt the ground
swayed to and fro, or was rent open as some unusually great
earth-movement took place, and perhaps a mountain range was raised
several feet or yards higher. All this we learn from the testimony of
the rocks beneath our feet. It only requires the use of a little
imagination to conjure up scenes of the past, and paint them as on a
moving diorama.
We shall not, however, dwell at any length on the scenery, or the
vegetation that clothed the landscape at different periods; for these
features are sufficiently indicated in the beautiful drawings of
extinct animals by our artist, Mr. J. Smit.
The researches of the illustrious Baron Cuvier, at Paris, as embodied
in his great work, _Ossemens Fossiles_, gave a great impetus to the
study of organic remains. It was he who laid the foundations of the
science of Palæontology,[2] which, though much has already been
accomplished, yet has a great future before it. Agassiz, Owen, Huxley,
Marsh, Cope, and others, following in his footsteps, have greatly
extended its boundaries; but he was the pioneer.
[2] Palæontology is the science which treats of the living beings,
whether animal or vegetable, which have inhabited this globe at past
periods in its history. (Greek--_palaios_, ancient; _onta_, beings;
_logos_, discourse.)
Before his time fossil forms were very little known, and still less
understood. His researches, especially among vertebrates, or backboned
animals, revealed an altogether undreamed-of wealth of entombed
remains. It is true the old and absurd notion that fossils were mere
"sports of Nature," sometimes bearing more or less resemblance to
living animals, but still only an accidental (!) resemblance, had been
abandoned by Leibnitz, Buffon, and Pallas; and that Daubenton had
actually compared the fossil bones of quadrupeds with those of living
forms; while Camper declared his opinion that some of these remains
belonged to extinct species of quadrupeds.
It is to Cuvier, however, that the world owes the first systematic
application of the science of comparative anatomy, which he himself
had done so much to place on a sound basis, to the study of the bones
of fossil animals. He paid great attention to the relative shapes of
animals, and the different developments of the same kind of bones in
various animals, and especially to the nature of their teeth. So great
did his experience and knowledge become, that he rarely failed in
naming an animal from a part of its skeleton. He appreciated more
clearly than others before him the mutual dependence of the various
parts of an animal's organisation. "The organism," he said, "forms a
connected unity, in which the single parts cannot change without
modifications in the other parts."
It will hardly be necessary to give examples of this now well-known
truth; but, just to take one case: the elephant has a long proboscis
with which it can reach the ground, and consequently its neck is quite
short; but take away the long proboscis, and you would seriously
interfere with the relation of various parts of its structure to each
other. How, then, could it reach or pick up anything lying on the
ground? Other changes would have to follow: either its legs would
require to be shortened, or its neck to be lengthened. In every
animal, as in a complex machine, there is a mutual dependence of the
different parts.
As he progressed in these studies, Cuvier was able with considerable
success to restore extinct animals from their fossilised remains, to
discover their habits and manner of life, and to point out their
nearest living ally. To him we owe the first complete demonstration of
the possibility of restoring an extinct animal. His "Law of
Correlation" however, has been found to be not infallible; as
Professor Huxley has shown, it has exceptions. It expresses our
experience among living animals, but, when applied to the more ancient
types of life, is liable to be misleading.
To take one out of many examples of this law: Carnivorous animals,
such as cats, lions, and tigers, have claws in their feet, very
different from the hoofs of an ox, which is herbivorous; while the
teeth of the former group are very different to those of the latter.
Thus the teeth and limbs have a certain definite relation to each
other, or, in other words, are correlated. Again, horned quadrupeds
are all herbivorous (or graminivorous), and have hoofs to their feet.
The following amusing anecdote serves to illustrate Cuvier's law. One
of his students thought he would try and frighten his master, and,
having dressed up as a wild beast, entered Cuvier's bedroom by night,
and, presenting himself by his bedside, said in hollow tones, "Cuvier,
Cuvier, I've come to eat you!" The great naturalist, who on waking up
was able to discern something with horns and hoofs, simply remarked,
"What! horns, hoofs--graminivorous--you can't!" What better lesson
could the master have given the pupil to help him to remember his "Law
of Correlation"?
Cuvier's great work, entitled _Ossemens Fossiles_, will long remain an
imperishable monument of the genius and industry of the greatest
pioneer in this region of investigation. This work proved beyond a
doubt to his astonished contemporaries the great antiquity of the
tribes of animals now living on the surface of the earth. It proved
more than that, however; for it showed the existence of a great
philosophy in Nature which linked the past with the present in a
scheme that pointed to a continuity of life during untold previous
ages. All this was directly at variance with the prevalent ideas of
his time, and consequently his views were regarded by many with alarm,
and he received a good deal of abuse--a fate which many other original
thinkers before him have shared.
It is somewhat difficult for people living now, and accustomed to
modern teaching, to realise how novel were the conclusions announced
by Cuvier. In his _Discourse on the Revolutions of the Surface of the
Globe_, translated into most European languages under the title
_Theory of the Earth_, he lays down, among others, the two following
propositions:--
1. That all organised existences were not created at the same
time; but at different times, probably very remote from each
other--vegetables before animals, mollusca and fishes before reptiles,
and the latter before mammals.
2. That fossil remains in the more recent strata are those which
approach nearest to the present type of corresponding living species.
Teaching such as this gave a new impetus to the study of organic
remains, and Palæontology, as a science, began with Cuvier.
CHAPTER I.
HOW EXTINCT MONSTERS ARE PRESERVED.
"Geology, beyond almost every other science, offers fields of
research adapted to all capacities and to every condition and
circumstance of life in which we may be placed. For while
some of its phenomena require the highest intellectual
powers, and the greatest attainments in abstract science for
their successful investigation, many of its problems may be
solved by the most ordinary intellect, and facts replete with
the deepest interest may be gleaned by the most casual
observer."--Mantell.
Let us suppose we are visiting a geological museum for the first time,
passing along from one department to another with ever-increasing
wonder--now admiring the beautiful polished marbles from Devonshire,
with their delicate corals, or the wonderful fishes from the Old Red
Sandstone, with their plates of enamel; now the delicate shells and
ammonites from the Lias or Oolites, with their pearly lustre still
preserved; now the white fresh-looking shells from the Isle of Wight;
now the ponderous bones and big teeth of ancient monsters from the
Wealden beds of Sussex. The question might naturally occur, "How were
all these creatures preserved from destruction and decay, and sealed
up so securely that it is difficult to believe they are as old as the
geologists tell us they are?" It will be worth our while to consider
this before we pass on to describe the creatures themselves.
Now, in the first place, "fossils" are not always "petrifactions," as
some people seem to think; that is to say, they are not all turned
into stone. This is true in many cases, no doubt, yet one frequently
comes across the remains of plants and animals that have undergone
very little change, and have, as it were, been simply sealed up. The
state of a fossil depends on several circumstances, such as the soil,
mud, or other medium in which it may happen to be preserved. Again,
the newest, or most recent, fossils are generally the least altered.
We have fossils of all ages, and in all states of preservation. As
examples of fossils very little altered, we may take the case of the
wonderful collection of bones discovered by Professor Boyd Dawkins in
caves in various parts of Great Britain. The results of many years of
research are given in his most interesting book on _Cave-Hunting_.
This enthusiastic explorer and geologist has discovered the remains of
a great many animals, some of which are quite extinct, while others
are still living in this country. These remains belong to a late
period, when lions, tigers, cave-bears, wolves, hyænas, and reindeer
inhabited our country. In some cases the caves were the dens of
hyænas, who brought their prey into caverns in our limestone rocks, to
devour them at their leisure; for the marks of their teeth may yet be
seen on the bones. In other cases the bones seem to have been washed
into the caves by old streams that have ceased to run; but in all
cases they are fairly fresh, though often stained by iron-rust brought
in by water that has dissolved iron out of various rocks--for iron is
a substance met with almost everywhere in nature. Sometimes they are
buried up in a layer of soil, or "cave-earth," and at other times in a
layer of stalagmite--a deposit of carbonate of lime gradually formed
on the floors of caves by the evaporation of water charged with
carbonate of lime.
Air and water are great destroyers of animal and vegetable substances
from which life has departed. The autumn leaves that fall by the
wayside soon undergo change, and become at last separated or resolved
into their original elements. In the same way when any wild animal,
such as a bird or rabbit, dies in an exposed place, its flesh decays
under the influence of rain and wind, so that before long nothing but
dry bones is left. Hamlet's wish that this "too too solid flesh would
melt" is soon realised after death; and that active chemical element
in the air known as oxygen, in breathing which we live, has a tenfold
power over dead matter, slowly causing chemical actions somewhat
similar to those that take place in a burning candle, whereby decaying
flesh is converted into water-vapour and carbonic acid gas. Thus we
see that oxygen not only supports life, but breaks up into simpler
forms the unwholesome and dangerous products of decaying matter, thus
keeping the atmosphere sweet and pure; but in time, even the dry bones
of the bird or rabbit, though able for a longer period to resist the
attacks of the atmosphere, crumble into dust, and serve to fertilise
the soil that once supported them.
Now, if water and air be excluded, it is wonderful how long even the
most perishable things may be preserved from this otherwise universal
decay. In the Edinburgh museum of antiquities may be seen an old
wooden cask of butter that has lain for centuries in peat--which
substance has a curiously preservative power; and human bodies have
been dug out of Irish peat with the flesh well preserved, which, from
the nature of the costume worn by the person, we can tell to be very
ancient. Meat packed in tins, so as to be entirely excluded from the
air, may be kept a very long time, and will be found to be quite fresh
and fit for use.
But air and water have a way of penetrating into all sorts of places,
so that in nature they are almost everywhere. Water can slowly filter
through even the hardest rocks, and since it contains dissolved air,
it causes the decay of animal or vegetable substances. Take the case
of a dead leaf falling into a lake, or some quiet pool in a river. It
sinks to the bottom, and is buried up in gravel, mud, or sand. Now,
our leaf will stand a very poor chance of preservation on a sandy or
gravelly bottom, because these materials, being porous, allow the
water to pass through them easily. But if it settles down on fine mud
it may be covered up and become a fossil. In time the soft mud will
harden into clay or shale, retaining a delicate impression of the
leaf; and even after thousands of years, the brown body of the leaf
will be there, only partly changed. In the case of the plants found in
coal, the lapse of ages since they were buried up has been so great
(and the strata have been so affected by the great pressure and by the
earth's internal heat) that certain chemical changes have converted
leaves and stems into carbon and some of its compounds, much in the
same way that, if you heat wood in a closed vessel, you convert it
into charcoal, which is mostly carbon. The coal we burn in our fires
is entirely of vegetable origin, and every seam in a coal-mine is a
buried forest of trees, ferns, reeds, and other plants.
The reader will understand how it is that rocks composed of hardened
sand or gravel, sandstones and conglomerates, contain but few fossils;
while, on the other hand, such rocks as clay, shale, slate, and
limestone often abound in fossils, because they are formed of what was
once soft mud, that sealed up and protected corals, shell-fish,
sea-urchins, fishes, and other marine animals. Had they been covered
up in sand the chances are that percolating water would have slowly
dissolved the shells and corals, the hard coats of the crabs, and the
bones of the fishes, all of which are composed of carbonate of lime;
and we know that is a substance easily dissolved by water.
It is in the rocks formed during the later geological periods that we
find fossils least changed from their original state; for time works
great changes, and too little time has elapsed since those periods for
any considerable alterations to have taken place. But when we come to
examine some of the earlier rocks, which have been acted upon in
various ways for long periods of time, such as the pressure of vast
piles of overlying rocks, and the percolation of water charged with
mineral substances (water sometimes warmed by the earth's internal
heat), then we may expect to find the remains of the world's lost
creations in a much more mineralised condition. Every fossil-collector
must be familiar with examples of changes of this kind. For instance,
shells originally composed of carbonate of lime are often found to
have been turned into flint or silica. Another curious change is
illustrated in the case of a stratum found in Cambridgeshire and other
counties. In this remarkable layer, only about a foot in thickness,
one frequently finds bones and teeth of fishes and reptiles. These,
however, have all undergone a curious change, whereby they have been
converted into phosphate of lime--a compound of phosphorus and lime.
It abounds in "nodules," or lumps, of this substance, which, along
with thousands of fossils, are every year ground up and converted by a
chemical process into valuable artificial manure for the farmer.
The soft parts of animals, as we have said before, cannot be preserved
in a fossil state; but, as if to compensate for this loss, we
sometimes meet with the most faithful and delicate impressions. Thus,
cuttle-fishes have, in some instances, left, on the clays which buried
them up, impressions of their soft, long arms, or tentacles, and, as
the mud hardened into solid rock, the impressions are fixed
imperishably. Examples of these interesting records may be seen at the
Natural History Museum at South Kensington. Even soft jelly-fishes
have left their mark on certain rocks! At a place in Bavaria, called
Solenhofen, there is a remarkably fine-grained limestone containing a
multitude of wonderful impressions. This stone is well known to
lithographers, and is largely used in printing. On it the oldest known
bird has left its skeleton and faithful impressions of its feathers.
The footprints of birds and reptiles are by no means uncommon. Such
records are most valuable, for a great deal may be learned from even a
footprint as to the nature of the animal that made it (see p. 79).
Since the greater number of animals described in this book are
reptiles, quadrupeds, and other inhabitants of the land, and only a
few had their home in the sea, we must endeavour to try and understand
how their remains may have been preserved. Our object in writing this
book is to interpret their story, and, as it were, to bring them to
life again. Each one must be made to tell its own story, and that
story will be far from complete if we cannot form some idea of how it
found its way into a watery grave, and so was added to Nature's
museum. For this purpose we must briefly explain to the reader how the
rocks we see around us have been deposited; for these rocks are the
tombs in which lost creations lie.
Go into any ordinary quarry, where the men are at work, getting out
the stone in blocks to be used in building, or for use on the roads,
or for some other purpose, and you will be pretty sure to notice at
the first glance that the rock is arranged as if it had been built up
in layers. Now, this is true of all rocks that have been laid down by
the agency of water--as most of them have been. True, there are
exceptions, but every rule has its exceptions. If you went into a
granite quarry at Aberdeen, or a basalt quarry near Edinburgh, you
would not see these layers; but such rocks as these do not contain
fossils. They have been mainly formed by the action of great heat, and
were forced up to the surface of the earth by pressure from below. As
they slowly cooled, the mineral substances of which they were formed
gradually crystallised; and it is this crystalline state, together
with the signs of movement, that tells us of their once heated state.
Such rocks are said to be of igneous origin (Lat. _ignis_, fire). But
nearly all the other rocks were formed by the action of water--that
is, under water,--and hence are known to geologists as aqueous
deposits (Lat. _aqua_, water). They may be considered as sediments
that slowly settled down in seas, lakes, or at the mouths of rivers.
Such deposits are in the course of being formed at the present day.
All round our coasts mud, sand, and gravel are being accumulated,
layer by layer. These materials are constantly being swept off the
land by the action of rain and rivers, and carried down to the sea.
Perhaps, when staying at the sea-side, you may have noticed, after
rainy and rough weather, how the sea, for some distance from the
shore, is discoloured with mud--especially at the mouth of a river.
The sand, being heavy, soon sinks down, and this is the reason why
sand-bars so frequently block the entrance to rivers. Then again, the
waves of the sea beat against the sea-shore and undermine the cliffs,
bringing down great fragments, which after a time are completely
broken up and worn down into rounded pebbles, or even fine sand and
mud. It is very easy to see that in this way large quantities of sand,
gravel, and mud are continually supplied to our seas. We can picture
how they will settle down; the sand not far from the shore, and the
fine mud further out to sea. When the rough weather ceases, the river
becomes smaller and flows less rapidly, so that when the coarse
_débris_ of the land has settled down to form layers, or strata, of
sand and gravel, then the fine mud will begin to settle down also, and
will form a layer overlying them or further out. Thus we learn, from a
little observation of what is now going on, how layers of sand and
mud, such as we see in a quarry, were made thousands and thousands of
years ago.
When we think of all the big rivers and small streams continually
flowing into the sea, we shall begin to realise what a great work rain
and rivers are doing in making the rocks of the future. If, at a later
period, a slight upheaval of the sea-bed were to take place so as to
bring it above water, and such is very likely, these materials would
be found neatly arranged in layers, and more or less hardened into
solid rock.
The reader may, perhaps, find it rather hard at first to realise that
in this simple way vast deposits of rock are being formed in the seas
of the present day, and that the finer material thus derived from a
continent may be carried by ocean currents to great distances; but so
it is. Over thousands of square miles of ocean, deposits are being
gradually accumulated which will doubtless be some day turned into
hard rock. Just to take one example: it has been found that in the
Atlantic Ocean, a distance of over two hundred miles from the mouth
of that great river, the Amazon, the sea is discoloured by fine
sediment.
There is another kind of rock frequently met with, the building up of
which cannot be explained in the way we have pointed out; and that is
limestone. This rock has not been deposited as a sediment, like clays
and sandstones, but geologists have good reasons for believing that it
has been gradually formed in the deeper and clearer parts of oceans by
the slow accumulation of marine shells, corals, and other creatures,
whose bodies are partly composed of carbonate of lime. This seems
incredible at first, but the proofs are quite convincing.[3] As
Professor Huxley well remarked, there is as good evidence that chalk
has been built up by the accumulation of minute shells as that the
Pyramids were built by the ancient Egyptians.
[3] See _The Autobiography of the Earth_, p. 223.
The science of geology reveals the startling fact that all the great
series of the stratified rocks, whose united thickness is over 80,000
feet, has been mainly accumulated under water, either by the action of
those powerful geological agents--rain and rivers--or through the
agency of myriads of tiny marine animals. When we have grasped this
idea, we have learned our first, and, perhaps, most useful lesson in
geology.
Now let us apply what has been above explained to the question
immediately before us. We want to know how the skeletons of animals
living on land came to be buried up under water, among the stratified
rocks that are to be seen all over our country, and most of which were
made under the sea.
We can answer this question by going to Nature herself, in order to
find out what is actually going on at the present time, by inquiring
into the habits of land animals, their surroundings, and the accidents
to which they are liable at sundry times and in divers manners. It is
by this simple method of studying present actions that nearly all
difficult questions in geology may be solved. The leading principle of
the geologist is to interpret the past by the light of the present,
or, in other words, to find out what happens now, in order to learn
what took place ages ago; for it is clear that the world has been
going on in the same way for at least as far back as geological
history can take us. There has been a _uniformity_, or sameness, in
Nature's actions ever since living things first dwelt on the earth.
Just as rivers are mainly responsible for bringing down to the sea the
materials of which rocks are made, so these universal carrying agents
are the means by which the bodies of many animals that live in the
plains, over which they wander, are brought to their last
resting-place. We have only to consult the records of great floods to
see what fearful havoc they sometimes make among living things, and
how the dead bodies are swept away.
Great floods rise rapidly, so that the herds of wild animals pasturing
on grassy plains are surprised by the rising waters, and, being unable
to withstand the force of the water, are hurried along, and so
drowned. When dead they sink to the bottom, and may, in some cases, be
buried up in the _débris_ hurried along by the river; but as a rule
their bodies, being swollen by the gases formed by decomposing flesh,
rise again to the surface, and consequently may be carried along for
many a mile, till they reach some lake, or perhaps right down to the
mouth of a river, and so may be taken out to sea.
One or two examples will be given to show how important is the action
of such floods. Sir Charles Lyell has given some striking
illustrations of this. There was a memorable flood in the southern
borders of Scotland on the 24th of June, 1794, which caused great
destruction in the region of the Solway Firth. Heavy rains had fallen,
so that every stream entering the firth was greatly swollen. Not only
sheep and cattle, but even herdsmen and shepherds were drowned. When
the flood had subsided, a fearful spectacle was seen on a large
sand-bank, called "the beds of Esk," where the waters meet; for on
this one bank were found collected together the bodies of 9 black
cattle, 3 horses, 1840 sheep, 45 dogs, 180 hares, together with those
of many smaller animals, also the corpses of two men and one woman.
Humboldt, the celebrated traveller, says that when, at certain
seasons, the large rivers of South America are swollen by heavy rains,
great numbers of quadrupeds are drowned every year. Troops of wild
horses that graze in the "savannahs," or grassy plains, are said to be
swept away in thousands.
In Java, in the year 1699, Batavian River was flooded during an
earthquake, and drowned buffaloes, tigers, rhinoceroses, deer, apes,
crocodiles, and other wild beasts, which were brought down to the
coast by the current.
In tropical countries, where very heavy rains fall at times, and
rivers become rapidly swollen, floods are a great source of danger to
man and beast. Probably the greater number of the bodies of animals
thus drowned find their way into lakes, through which rivers flow, and
never reach the sea; and if the growth of sediment in such lakes goes
on fairly rapidly, their remains may be buried up, and so preserved.
But in many cases the bones fall one by one from the floating carcase,
and so may in that way be scattered at random over the bottom of the
lake, or the bed of a river at its mouth. In hot countries such
bodies, on reaching the sea, run a great chance of being instantly
devoured by sharks, alligators, and other carnivorous animals. But
during very heavy floods, the waters that reach the sea are so heavily
laden with mud, that these predaceous animals are obliged to retire to
some place where the waters are clear, so that at such times the dead
bodies are more likely to escape their ravages; and, at the same time,
the mud with which the waters are charged falls so rapidly that it may
quickly cover them up. We shall find further on that this explanation
probably applies to the case of the "fish-lizards," whose remains are
found in the Lias formation (see p. 51).
But, for several reasons, sedimentary rocks formed in lakes are much
more likely to contain the remains of land animals, than those that
were formed in seas, and they are more likely to be in a complete
state of preservation. Within the last century, five or six small
lakes in Scotland, which had been artificially drained, yielded the
remains of several hundred skeletons of stags, oxen, boars, horses,
sheep, dogs, hares, foxes, and wolves. There are two ways in which
these animals may have met with a watery grave. In the first place,
they may have got mired on going into the water, or in trying to land
on the other side, after swimming across. Any one who knows Scotch
lakes will be familiar with the fact that their margins are often most
treacherous ground for bathers. The writer has more than once found it
necessary to be very cautious on wading into a lake while fishing, or
in search of plants. Secondly, when such lakes are frozen over in
winter, the ice is often very treacherous in consequence of numerous
springs; and animals attempting to cross may be easily drowned. No
remains of birds were discovered in these lakes, in spite of the fact
that, until drained, they were largely frequented by water-fowl. But
it must be remembered that birds are protected by their powers of
flight from perishing in such ways as other animals frequently do.
And, even should they die on the water, their bodies are not likely to
be submerged; for, being light and feathery, they do not sink, but
continue floating until the body rots away, or is devoured by some
creature such as a hungry pike. For these reasons the remains of birds
are unfortunately very rare in the stratified rocks; and hence our
knowledge of the bird life of former ages is slight.
The Imperfection of the Record.
A very little consideration will serve to convince us that the record
which Nature has kept in the stratified rocks is an incomplete one.
There are many reasons why it must be so. It is not to be expected
that these rocks should contain anything like a complete collection of
the remains of the various tribes of plants and animals that from time
to time have flourished in seas, lakes, and estuaries, or on islands
and continents of the world. In endeavouring to trace the course of
life on the globe at successive periods, we are continually met by
want of evidence due to the "imperfection of the record"--to use
Darwin's phrase. The reasons are not far to seek. The preservation of
organic remains, or even of impressions thereof, in sedimentary strata
is, to some extent, a matter of chance. It is obvious that no wholly
soft creature, such as a jelly-fish, can be preserved; although on
some strata they have left impressions telling of their existence at a
very early period.
A creature, to become fossilised, must possess some hard part, such as
a shell, _e.g._ an oyster (fossil oysters abound in some strata); or a
hard chitinous covering, like that of the shrimp, or the trilobites of
Silurian times; or a skeleton, such as all the backboned (vertebrate)
animals possess.
But even creatures that had skeletons have not by any means always
been preserved. Bones, when left on the bottom of the sea, where no
sediment, or very little, is forming, will decay, and so disappear
altogether. As Darwin points out, we are in error in supposing that
over the greater part of the ocean-bed of the present day sediment is
deposited fast enough to seal up organic remains before they can
decay. Over a large part of the ocean-bed such cannot be the case; and
this conclusion has, of late years, been confirmed by the observations
made during the fruitful voyage of H.M.S. _Challenger_ in the Atlantic
and Pacific Oceans.
Again, even in shallower parts of the old seas, where sand or mud was
once deposited, fossilisation was somewhat accidental; for some
materials, being porous, allow of the percolation of water, and in
this way shells, bones, etc., have been dissolved and lost. Thus
sandstone strata are always barren in fossils compared to shales and
limestones, which are much less pervious. To take examples from our
own country, the New Red Sandstone of the south-west of England, the
midland counties, Cheshire, and other parts contains very few fossils
indeed, while the clays and limestones of the succeeding Lias period
abound in organic remains of all sorts. Even insects have left
delicate impressions of their wings and bodies! while shells, corals,
encrinites, fish-teeth, and bones of saurians are found in great
numbers.
Again, it must be borne in mind that the series of stratified rocks
known to geologists is not complete or unbroken. They have been well
compared to the leaves of a book on history, of which whole chapters
and many separate pages have been torn out. These gaps, or "breaks,"
are due to what is called "denudation;" that is to say, a great many
rocks, after having been slowly deposited in water, have been upraised
to form dry land, and then, being subjected for ages to the destroying
action of "rain and rivers," or the waves of the sea, have been
largely destroyed. Such rocks, in the language of geology, have been
"denuded;" that is, stripped off, so that the underlying rocks are
left bare.
But the process of rock-making does not go on continuously in any one
area. Sedimentary strata have been formed in slowly sinking areas.
But, if subsidence ceases, and the downward movement becomes an upward
one, then the bed of the sea is converted into dry land, and the
geological record is broken; for aqueous strata do not form on dry
land. Blown sands and terrestrial lava-flows are exceptions; but such
accumulations are very small and insignificant, and may therefore be
neglected, especially as they contain no fossils.
In this way, as well as by the process of "denudation" already alluded
to, breaks occur; and these breaks often represent long intervals of
time. There are several such gaps in the British series of stratified
rocks; and it is partly by means of these breaks, during which
important geographical and other changes took place, that sedimentary
rocks have been classified and arranged in groups representing
geological periods. Thus, the Cainozoic, or Tertiary, rocks of the
Thames' basin are separated by a long "break" from those of the
preceding Cretaceous period. During that interval great changes in
animal life took place, whereby, in the course of evolution, new types
appeared on the scene. (See Table of Strata, Appendix I.)
Another cause interfering with the record is to be found in those
important internal changes that have taken place in stratified
rocks--often over large areas--which may be ascribed to the influence
of heat and pressure combined. This process of change, whereby soft
deposits have been altered or "metamorphosed" into hard crystalline
rocks, is known as "metamorphism." Metamorphic rocks have lost not
only their original structure and appearance, but also their included
organic remains, or fossils. Thus, when a soft limestone has been
converted by these means into crystalline statuary marble, any fossils
it may once have contained have been destroyed. It is true that this
applies more to older and lower deposits,--for the lowest are the
oldest--but there can be no doubt that valuable records of the forms
of life which peopled the world in former periods have been lost by
this means.
And lastly, it must ever be borne in mind that, as yet, our knowledge
of the stratified rocks of the earth's crust is very limited. In
course of time, no doubt, this deficiency will be to a great extent
made good; but it will take a long time. Already, within the last
thirty years, the labours of zealous geologists in the colonies and in
various countries have added largely to our knowledge of the
geological record. Still, only a small portion of the earth's surface
has at present been explored; and doubtless one may look forward to
future discoveries of extinct forms of animal and plant life as
wonderful and strange as those that have been of late years unearthed
in the "far West," in Africa, and India. The Siwalik Hills of Northern
India offer a rich harvest of fossils to future explorers. Already,
one remarkable and large horned quadruped has come from this region;
and it is known that other valuable treasures are sealed up within
these hills, only awaiting the "open sesame" of some enterprising
explorer to bring them to light.
As previously pointed out, deposits formed in lakes are the most
promising field for geologists in search of the remains of old
terrestrial quadrupeds and reptiles; but, unfortunately, such deposits
are rare.
It is very much to be regretted that the carelessness and indifference
of ignorant workmen in quarries, clay-pits, and railway cuttings have
sometimes been the cause of valuable fossils being broken up, and so
lost for ever. Unless they are accustomed to the visits of
fossil-collectors who will pay them liberally for their finds, the men
will not take the trouble to preserve any bones they may come across
in the course of their work. (An example of this negligence will be
found on p. 95.) But when once they realise that such finds have what
political economists call an "exchange value," or, in other words, can
be turned into money, it is astonishing what zealous guardians of
Nature's treasures they become! For this reason collectors often find
what Professor Bonney calls the "silver hammer"--in other words,
cash--more effective than the iron implement they carry with them.