encounters, for one is broken midway between tip and base; and that it
was broken during life is evident from the fact that the stump is healed
and rounded over, while the size of the horns shows that their owner
reached a ripe old age.
For, unlike man and the higher vertebrates, reptiles and fishes do not
have a maximum standard of size which is soon reached and rarely
exceeded, but continue to grow throughout life, so that the size of a
turtle, a crocodile, or a Dinosaur tells something of the duration of
its life.
Before quitting Triceratops let us glance for a moment at its skeleton.
Now among other things a skeleton is the solution of a problem in
mechanics, and in Triceratops the head so dominates the rest of the
structure that one might almost imagine the skull was made first and the
body adjusted to it. The great head seems made not only for offence and
defence; the spreading frill serves for the attachment of muscles to
sustain the weight of the skull, while the work of the muscles is made
easier by the fact that the frill reaches so far back of the junction of
head with neck as to largely counterbalance the weight of the face and
jaws. When we restored the skull of this animal it was found that the
centre of gravity lay back of the eye. Several of the bones of the neck
are united in one mass to furnish a firm attachment for the muscles that
support and move the skull, but as the movements of the neck are already
restricted by the overhanging frill, this loss of motion is no
additional disadvantage.
[Illustration: TRICERATOPS PRORSUS Marsh Fig. 22.--Skeleton of
Triceratops.]
To support all this weight of skull and body requires very massive
legs, and as the fore legs are very short, this enables Triceratops to
browse comfortably from the ground by merely lowering the front of the
head.
These forms we have been considering were the giants of the group, but a
commoner species, Thespesius, though less in bulk than those just
mentioned, was still of goodly proportions, for, as he stalked about,
the top of his head was twelve feet from the ground.
Thespesius and his kin seem to have been comparatively abundant, for
they have a wide distribution, and many specimens, some almost perfect,
have been discovered in this country and abroad. No less than
twenty-nine Iguanodons, a European relative of Thespesius, were found in
one spot in mining for coal at Bernissart, Belgium. Here, during long
years of Cretaceous time, a river slowly cut its way through the
coal-bearing strata to a depth of 750 feet, a depth almost twice as
great as the deepest part of the gorge of Niagara, and then, this being
accomplished, began the work of filling up the valley it had excavated.
It was then a sluggish stream with marshy borders, a stream subject to
frequent floods, when the water, turbid with mud and laden with sand,
overflowed its banks, leaving them, as the waters subsided, covered
thickly with mud. Here, amidst the luxuriant vegetation of a
semi-tropical climate, lived and died the Iguanodons, and here the pick
of the miner rescued them from their long entombment to form part of the
treasures of the museum at Brussels.
Like other reptiles, living and extinct, Thespesius was continually
renewing his teeth, so that as fast as one tooth was worn out it was
replaced by another, a point wherein Thespesius had a decided advantage
over ourselves. On the other hand, as there was a reserve supply of
something like 400 teeth in the lower jaw alone, what an opportunity for
the toothache!
And then we have a multitude of lesser Dinosaurs, including the active,
predatory species with sharp claws and double-edged teeth. Megalosaurus,
the first of the Dinosaurs to be really known, was one of these
carnivorous species, and from our West comes a near relative,
Ceratosaurus, the nose-horned lizard, a queer beast with tiny fore legs,
powerful, sharp-clawed hind feet, and well-armed jaws. A most formidable
foe he seems, the more that the hollow bones speak of active movements,
and Professor Cope pictured him, or a near relative, vigorously engaged
in combat with his fellows, or preying upon the huge but helpless
herbivores of the marshes, leaping, biting, and tearing his enemy to
pieces with tooth and claw.
Professor Osborn, on the other hand, is inclined to consider him as a
reptilian hyena, feeding upon carrion, although one can but feel that
such an armament is not entirely in the interests of peace.
Last, but by no means least, are the Stegosaurs, or plated lizards, for
not only were they beasts of goodly size, but they were among the most
singular of all known animals, singular even for Dinosaurs. They had
diminutive heads, small fore legs, long tails armed on either side near
the tip, with two pairs of large spines, while from these spines to the
neck ran series of large, but thin, and sharp-edged plates standing
on edge, so that their backs looked like the bottom of a boat provided
with a number of little centreboards. Just how these plates were
arranged is not decided beyond a peradventure, but while originally
figured as having them in a single series down the back it seems much
more probable that they formed parallel rows.
[Illustration: Fig. 23.--The Horned Ceratosaurus. A Carnivorous
Dinosaur. _From a drawing by J. M. Gleeson._]
The largest of these plates were two feet in height and length, and not
more than an inch thick, except at the base, where they were enlarged
and roughened to give a firm hold to the thick skin in which they were
imbedded. Be it remembered, too, that these plates and spines were
doubtless covered with horn, so that they were even longer in life than
as we now see them. The tail spines varied in length, according to the
species, from eight or nine inches to nearly three feet, and some of
them have a diameter of six inches at the base. They were swung by a
tail eight to ten feet long, and as a visitor was heard to remark, one
wouldn't like to be about such an animal in fly time.
Such were some of the strange and mighty animals that once roamed this
continent from the valley of the Connecticut, where they literally left
their footprints on the sands of time, to the Rocky Mountains, where the
ancient lakes and rivers became cemeteries for the entombment of their
bones.
The labor of the collector has gathered their fossil remains from many a
Western canyon, the skill of the preparator has removed them from their
stony sepulchres and the study of the anatomist has restored them as
they were in life.
_REFERENCES._
_Most of our large museums have on exhibition fine specimens of many
Dinosaurs, comprising skulls, limbs, and large portions of their
skeletons. The American Museum of Natural History, New York, has the
largest and finest display. The first actual skeleton of a Dinosaur to
be mounted in this country was the splendid Claosaurus at the Yale
University Museum, where other striking pieces are also to be seen. The
mounting of this Claosaurus, which is 29 feet long and 13 feet high,
took an entire year. The United States National Museum is
particularly rich in examples of the great, horned Triceratops, while
the Carnegie Museum, Pittsburgh, has the best Diplodocus. The Field
Columbian Museum and the Universities of Wyoming and Colorado all have
good collections._
[Illustration: Fig. 24.--Stegosaurus. An Armored Dinosaur of the
Jurassic. _From a drawing by Charles R. Knight._]
_The largest single bone of a Dinosaur is the thigh bone of a
Brontosaurus in the Field Columbian Museum, this measuring 6 feet 8
inches in length. The height of a complete hind leg in the American
Museum of Natural History is 10 feet, while a single claw measures 6 by
9 inches. The skeleton of Triceratops restored in papier-mache for the
Pan-American Exposition measured 25 feet from tip of nose to end of tail
and was 10 feet 6 inches to the top of the backbone over the hips, this
being the highest point. The head in the United States National Museum
used as a model is 5 feet 6 inches long in a straight line and 4 feet 3
inches across the frill. There is a skull in the Yale University Museum
even larger than this._
_Articles relating to Dinosaurs are mostly technical in their nature and
scattered through various scientific journals. The most accessible
probably is "The Dinosaurs of North America," by Professor O. C. Marsh,
published as part of the sixteenth annual report of the United States
Geological Survey. This contains many figures of the skulls, bones, and
entire skeletons of many Dinosaurs._
[Illustration: Fig. 25.--Skull of Ceratosaurus. _From a specimen in the
United States National Museum._]
VII
READING THE RIDDLES OF THE ROCKS
"_And the first Morning of Creation wrote
What the Last Dawn of Reckoning shall read._"
It is quite possible that the reader may wish to know something of the
manner in which the specimens described in these pages have been
gathered, how we acquire our knowledge of Brontosaurus, Claosaurus, or
any of the many other "sauruses," and how their restorations have been
made.
There was a time, not so very long ago, when fossils were looked upon as
mere sports of Nature, and little attention paid to them; later their
true nature was recognized, though they were merely gathered haphazard
as occasion might offer. But now, and for many years past, the
fossil-bearing rocks of many parts of the world have been systematically
worked, and from the material thus obtained we have acquired a great
deal of information regarding the inhabitants of the ancient world. This
is particularly true of our own western country, where a vast amount of
collecting has been done, although very much remains to be done in the
matter of perfecting this knowledge, and hosts of new animals remain to
be discovered. For this information we are almost as much indebted to
the collector who has gathered the needed material, and the preparator
whose patience and skill have made it available for study, as to the
palaeontologist who has interpreted the meaning of the bones.
To collect successfully demands not only a knowledge of the rocks in
which fossils occur and of the localities where they are best exposed to
view, but an eye quick to detect a piece of bone protruding from a rock
or lying amongst the shale, and, above all, the ability to work a
deposit to advantage after it has been found. The collector of living
animals hies to regions where there is plenty for bird and beast to eat
and drink, but the collector of extinct animals cares little for what is
on the surface of the earth; his great desire is to see as much as
possible of what may lie beneath. So the prospector in search of fossils
betakes himself to some region where the ceaseless warfare waged by
water against the dry land has seamed the face of the earth with
countless gullies and canyons, or carved it into slopes and bluffs in
which the edges of the bone-bearing strata are exposed to view, and
along these he skirts, ever on the look-out for some projecting bit of
bone. The country is an almost shadeless desert, burning hot by day,
uncomfortably cool at night. Water is scarce, and when it can be found,
often has little to commend it save wetness; but the collector is buoyed
up through all this with the hope that he may discover some creature new
to science that shall not only be bigger and uglier and stranger than
any heretofore found, but shall be the long-sought form needed for the
solution of some difficult problem in the history of the past.
Now collecting is a lottery, differing from most lotteries, however, in
that while some of the returns may be pretty small, there are few
absolute blanks and some remarkably large prizes, and every collector
hopes that it may fall to his lot to win one of these, and is willing to
work long and arduously for the chance of obtaining it.
It may give some idea of the chances to say that some years ago Dr.
Wortman spent almost an entire season in the field without success, and
then, at the eleventh hour, found the now famous skeleton of Phenacodus,
or that a party from Princeton actually camped within 100 yards of a
rich deposit of rare fossils and yet failed to discover it.
Let us, however, suppose that the reconnaissance has been successful,
and that an outcrop of bone has been found, serving like a tombstone
carven with strange characters to indicate the burial-place of some
primeval monster. Possibly Nature long ago rifled the grave, washing
away much of the skeleton, and leaving little save the fragments visible
on the surface; on the other hand, these pieces may form part of a
complete skeleton, and there is no way to decide this important question
save by actual excavation. The manner of disinterment varies, but much
depends on whether the fossil lies in comparatively loose shale or is
imbedded in the solid rock, whether the strata are level or dip downward
into the hillside. If, unfortunately, this last is the case, it
necessitates a careful shoring up of the excavation with props of
cotton-wood or such boards as may have been brought along to box
specimens, or it may even be necessary to run a short tunnel in order to
get at some coveted bone. Should the specimen lie in shale, as is the
case with most of the large reptiles that have been collected, much of
that work may be done with pick and shovel; but if it is desirable or
necessary to work in firm rock, drills and hammers, wedges, even powder,
may be needed to rend from Nature her long-kept secrets. In any event, a
detailed plan is made of the excavation, and each piece of bone or
section of rock duly recorded therein by letter and number, so that
later on the relation of the parts to one another may be known, or the
various sections assembled in the work-room exactly as they lay in the
quarry. Bones which lie in loose rock are often, one might say usually,
more or less broken, and when a bone three, four, or even six feet
long, weighing anywhere from 100 to 1,000 pounds, has been shattered to
fragments the problem of removing it is no easy one. But here the skill
of the collector comes into play to treat the fossil as a surgeon treats
a fractured limb, to cover it with plaster bandages, and brace it with
splints of wood or iron so that the specimen may not only be taken from
the ground but endure in safety the coming journey of a thousand or more
miles. For simpler cases or lighter objects strips of sacking, or even
paper, applied with flour and water, suffice, or pieces of sacking
soaked in thin plaster may be laid over the bone, first covering it with
thin paper in order that the plaster jacket may simply stiffen and not
adhere to it. Collecting has not always been carried on in this
systematic manner, for the development of the present methods has been
the result of years of experience; formerly there was a mere
skimming-over of the surface in what Professor Marsh used to term the
potato-gathering style, but now the effort is made to remove specimens
intact, often imbedded in large masses of rock, in order that all parts
may be preserved.
We will take it for granted that our specimens have safely passed
through all perils by land and water, road and rail; that they have been
quarried, boxed, carted over a roadless country to the nearest railway,
and have withstood 2,000 miles of jolting in a freight-car. The first
step in reconstruction has been taken; the problem, now that the boxes
are reposing on the work-room floor, is to make the blocks of stone give
up the secrets they have guarded for ages, to free the bones from their
enveloping matrix in order that they may tell us something of the life
of the past. The method of doing this varies with the conditions under
which the material has been gathered, and if from hard clay, chalk, or
shale, the process, though tedious enough at best, is by no means so
difficult as if the specimens are imbedded in solid rock. In this case
the fragments from a given section of quarry must be assembled according
to the plan which has been carefully made as the work of exhumation
progressed, all pieces containing bone must be stuck together, and weak
parts strengthened with gum or glue. Now the mass is attacked with
hammer and chisel, and the surrounding matrix slowly and carefully cut
away until the contained bone is revealed, a process much simpler and
more expeditious in the telling than in the actuality; for the
preparator may not use the heavy tools of the ordinary stone-cutter:
sometimes an awl, or even a glover's needle, must suffice him, and the
chips cut off are so small and such care must be taken not to injure the
bone that the work is really tedious. This may, perhaps, be better
appreciated by saying that to clean a single vertebra of such a huge
Dinosaur as Diplodocus may require a month of continuous labor, and that
a score of these big and complicated bones, besides others of simpler
structure, are included in the backbone. The finished specimen weighs
over 120 pounds, while as originally collected, with all the adherent
rock, the weight was twice or thrice as great. Such a mass as this is
comparatively small, and sometimes huge blocks are taken containing
entire skulls or a number of bones, and not infrequently weighing a
ton. The largest single specimen is a skull of Triceratops, collected by
Mr. J. B. Hatcher, which weighed, when boxed, 3,650 pounds.
Or, as the result of some mishap, or through the work of an
inexperienced collector, a valuable specimen may arrive in the shape of
a box full of irregular fragments of stone compared with which a
dissected map or an old-fashioned Chinese puzzle is simplicity itself,
and one may spend hours looking for some piece whose proper location
gives the clew to an entire section, and days, even, may be consumed
before the task is completed. While this not only tries the patience,
but the eyes as well, there is, nevertheless, a fascination about this
work of fashioning a bone out of scores, possibly hundreds, of
fragments, and watching the irregular bits of stone shaping themselves
into a mosaic that forms a portion of some creature, possibly quite new
to science, and destined to bear a name as long as itself. And thus,
after many days of toil, the bone that millions of years before sank
into the mud of some old lake-bottom or was buried in the sandy shoals
of an ancient river, is brought to light once more to help tell the tale
of the creatures of the past.
One bone might convey a great deal of information; on the other hand it
might reveal very little; for, while it is very painful to say so, the
popular impression that it is possible to reconstruct an animal from a
single bone, or tell its size and habits from a tooth is but partially
correct, and sometimes "the eminent scientist" has come to grief even
with a great many bones at his disposal. Did not one of the ablest
anatomists describe and figure the hip-bones of a Dinosaur as its
shoulder-blade, and another, equally able, reconstruct a reptile "hind
side before," placing the head on the tail! This certainly sounds absurd
enough; but just as absurd mistakes are made by men in other walks of
life, often with far more deplorable results.
Before passing to the restoration of the exterior of animals it may be
well to say something of the manner in which the skeleton of an extinct
animal may be reconstructed and the meaning of its various parts
interpreted. For the adjustment of the muscles is dependent on the
structure of the skeleton, and putting on the muscles means blocking out
the form, details of external appearance being supplied by the skin and
its accessories of hair, scales, or horns. Let us suppose in the present
instance that we are dealing with one of the great reptiles known as
Triceratops whose remains are among the treasures of the National Museum
at Washington, for the reconstruction of the big beast well illustrates
the methods of the palaeontologist and also the troubles by which he is
beset. Moreover, this is not a purely imaginary case, but one that is
very real, for the skeleton of this animal which was shown at Buffalo
was restored in papier-mache in exactly the manner indicated. We have a
goodly number of bones, but by no means an entire skeleton, and yet we
wish to complete the skeleton and incidentally to form some idea of the
creature's habits. Now we can interpret the past only by a knowledge of
the present, and it is by carefully studying the skeletons of the
animals of to-day that we can learn to read the meaning of the symbols
of bones left by the animals of a million yesterdays. Thus we find that
certain characters distinguish the bone of a mammal from that of a bird,
a reptile, or a fish, and these in turn from one another, and this
constitutes the A B C of comparative anatomy. And, in a like manner, the
bones of the various divisions of these main groups have to a greater or
less extent their own distinguishing characteristics, so that by first
comparing the bones of extinct animals with those of creatures that are
now living we are enabled to recognize their nearest existing relative,
and then by comparing them with one another we learn the relations they
bore in the ancient world. But it must be borne in mind that some of the
early beasts were so very different from those of to-day that until
pretty much their entire structure was known there was nothing with
which to compare odd bones. Had but a single incomplete specimen of
Triceratops come to light we should be very much in the dark concerning
him; and although remains of some thirty individuals have been
discovered, these have been so imperfect that we are very far from
having all the information we need. A great part of the head, with its
formidable looking horns, is present, and although the nose is gone, we
know from other specimens that it, too, was armed with a knob, or horn,
and that the skull ended in a beak, something like that of a snapping
turtle, though formed by a separate and extra bone; similarly the end of
the lower jaw is lacking, but we may be pretty certain that it ended in
a beak, to match that of the skull. The large leg-bones of our specimen
are mostly represented, for these being among the more solid parts of
the skeleton are more frequently preserved than any others, and though
some are from one side and some from another, this matters not. If the
hind legs were disproportionately long it would indicate that our animal
often or habitually walked erect, but as there is only difference enough
between the fore and hind limbs to enable Triceratops to browse
comfortably from the ground we would naturally place him on all fours,
even were the skull not so large as to make the creature too top-heavy
for any other mode of locomotion. Were the limbs very small in
comparison with the other bones, it would obviously mean that their
owner passed his life in the water. For a skeleton has a twofold
meaning, it is the best, the most enduring, testimony we have as to an
animal's place in nature and the relationships it sustains to the
creatures that lived with it, before it, and after it. More than this, a
skeleton is the solution of a problem in mechanics, the problem of
carrying a given weight and of adaptation to a given mode of life. Thus
the skeleton varies according as a creature dwells on land, in the
water, or in the air, and according as it feeds on grass or preys upon
its fellows.
And so the mechanics of a skeleton afford us a clew to the habits of the
living animal. Something, too, may be gathered from the structure of the
leg-bones, for solid bones mean either a sluggish animal or a creature
of more or less aquatic habits, while hollow bones emphatically declare
a land animal, and an active one at that; and this, in the case of the
Dinosaurs, hints at predatory habits, the ability to catch and eat their
defenceless and more sluggish brethren. A claw, or, better yet, a
tooth, may confirm or refute this hint; for a blunt claw could not be
used in tearing prey limb from limb, nor would a double-edged tooth,
made for rending flesh, serve for champing grass.