DINOSAURS
Chapter 11:
COLLECTING DINOSAURS.
How and Where
They are Found.
The visitor who is
introduced to the dinosaurs through the medium of books and pictures or of the
skeletons exhibited in the great museums, finds it hard—well nigh impossible—to
realize their existence. However willing he may be to accept on faith the
reconstructions of the skeletons, the restorations of the animals and their
supposed environment, it yet remains to him somewhat of a fairy-tale, a fanciful
imaginative world peopled with ogres and dragons and belonging to the unreal
"once upon a time" which has no connection with the ever present workaday world
in which we live. Birds and squirrels, rabbits and foxes belong to this real
world because he has seen them in his walks through the woods; even elephants
and rhinoceroses, though his acquaintance be limited to menagerie specimens,
seem fairly real—although one recalls the farmer's comment on first seeing a
giraffe in the Zoological park: "There aint no sich animal." But dinosaurs—one
easily realizes the state of mind that prompts the inquiry so often made by
visitors to the Dinosaur Hall:—"they make these out of plaster, don't they?" So
far as is consistent with good taste, the aim of the American Museum has been to
enable the visitor to see for himself how much of plaster reconstruction there
is to each skeleton, and to explain in the labels what the basis was for the
reconstructed parts.How They are Found. But to the collector these
extinct animals are real enough. As he journeys over the western plains he sees
the various living inhabitants thereof, birds and beasts, as well as men,
pursuing their various modes of life; here and there he comes across the
scattered skeletons or bones of modern animals lying strewn upon the surface of
the ground or half buried in the soil of a cut bank. In the shales or sandstones
that underlie the soil he finds the objects of his search, skeletons or bones of
extinct animals, similarly disposed, but buried in rock instead of soft soil,
and exposed in cañons and gullies cut through the solid rock. Each rock
formation, he knows by precept and experience, carries its own peculiar fauna,
its animals are different from those of the formation above and from those in
the formation below. Days and weeks he may spend in fruitless search following
along the outcrop of the formation, through rugged badlands, along steep cañon
walls, around isolated points or buttes, without finding more than a few
fragments, but spurred on by vivid interest and the rainbow prospect of some new
or rare find. Finally perhaps, after innumerable disappointments, a trail of
fragments leads up to a really promising prospect. A cautious investigation
indicates that an articulated skeleton is buried at this point, and that not too
much of it has "gone out" and rolled in weathered fragments down the slope. For
the tedious and delicate process of disinterring the skeleton from the rock he
will need to keep ever in mind the form and relations of each bone, the picture
of the skeleton as it may have been when buried. The heavy ledges above are
removed with pick and shovel, often with help of dynamite and a team and
scraper. As he gets nearer to the stratum in which the bones lie the work must
be more and more careful. A false blow with pick or chisel might destroy
irreparably some important bony structure. Bit by bit he traces out the position
and lay of the bones, working now mostly with awl and whisk-broom, uncovering
the more massive portions, blocking out the delicate bones in the rock, soaking
the exposed surfaces repeatedly with thin "gum" (mucilage) or shellac,
channeling around and between the bones until they stand out on little pedestals
above the quarry floor. Then, after the gum or shellac has dried thoroughly and
hardened the soft parts, and the surfaces of bone exposed are further protected
by pasting on a layer of tissue paper, it is ready for the "plaster jacket."
This consists of strips of burlap dipped in plaster-of-paris and pasted over the
surface of each block until top and sides, all but the pedestal on which it
rests, are completely cased in, the strips being pressed and kneaded close to
the surface of the block as they are laid on. When this jacket sets and dries
the block is rigid and stiff enough to lift and turn over; the remains of the
pedestal are trimmed off and the under surface is plastered like the rest. With
large blocks it is often necessary to paste into the jacket, on upper or both
sides, boards, scantling or sticks of wood to secure additional rigidity. For
should the block "rack," or become shattered inside, even though no fragments
were lost, the specimen would be more or less completely ruined.
Fig. 41.—A Dinosaur skeleton, prospected and ready
for encasing in plaster bandages and removal in
blocks. (Corythosaurus, Red Deer River,
Alberta.)
The next stage will be packing in boxes with straw,
hay or other materials, hauling to the railway and
shipment to New York.
Arrived at the Museum, the boxes are unpacked, each
block laid out on a table, the upper side of its plaster
jacket softened with water and cut away, and the
preparation of the bone begins. Always it is more or
less cracked and broken up, but the fragments lie in
their natural relations. Each piece must be lifted out,
thoroughly cleaned from rock and dirt, and the fractured
surfaces cemented together again. Parts of bones,
especially the interior, are often rotted into dust
while the harder outer surface is still preserved. The
dust must be scraped out, the interior filled with a
plaster cement, and the surface pieces re-set in
position. Very often a steel rod is set into the plaster
filling the interior of a bone, to secure additional
strength.
After this preparation is completed, each part being
soaked repeatedly with shellac until it will absorb no
more, the bones can be handled and laid out for study or
exhibition. Then, if they are to be mounted for a fossil
skeleton, comes the work of restoring the missing parts.
For this a plaster composition is used.
Where only parts of one side are missing the
corresponding parts of the other side are used for
model; where both sides are missing, other individuals
or nearly related species may serve as a guide. But it
is seldom wise to attempt restoration of a skeleton
unless at least two-thirds of it is present; composite
skeletons made up of the remains of several or many
individuals, have been attempted, but they are dangerous
experiments in animals so imperfectly known as are most
of the dinosaurs. There is too much risk of including
bones that pertain to other species or genera, and of
introducing thereby into the restoration a more or less
erroneous concept of the animal which it represents. The
same criticism applies to an overly large amount of
plaster restoration.
Fig. 42.—Bone-Cabin Draw on Little Medicine River
north of Medicine Bow, Wyoming. The location of the
quarry is indicated by the stack of crated specimens
on the left, and close to it the low sod-covered
shack where the collecting party lived. Beyond the
draw lies the flat rolling surface of the Laramie
Plains and on the southern horizon the Medicine Bow
Range with Elk Mountain at the center.
In some instances the missing parts of a skeleton are
not restored, because, even though but a small part be
gone, we have no good evidence to guide in its
reconstruction. This gives an imperfect and sometimes
misleading concept of what the whole skeleton was like,
but it is better than restoring it erroneously. Usually
with the more imperfect skeletons, a skull, a limb or
some other characteristic parts may be placed on
exhibition but the remainder of the specimen is stored
in the study collections.
Fig. 43.—American Museum party at Bone-Cabin Quarry,
1899. Seated, left to right Walter Granger,
Professor H.F. Osborn, Dr. W.D. Matthew; standing,
F. Schneider, Prof. R.S. Lull, Albert Thomson, Peter
Kaison.
Where They are Found. The chief dinosaur
localities in this country are along the flanks of the
Rocky Mountains and the plains to the eastward, from
Canada to Texas. Not that dinosaurs were any more
abundant there than elsewhere. They probably ranged all
over North America, and different kinds inhabited other
continents as well. But in the East and the Middle West,
the conditions were not favorable for preserving their
remains, except in a few localities. Formations of this
age are less extensive, especially those of the delta
and coast-swamps which the dinosaurs frequented. And
where they do occur, they are largely covered by
vegetation and cannot be explored to advantage. In the
arid Western regions these formations girdle the Rockies
and outlying mountain chains for two-thousand miles from
north to south, and are extensively exposed in great
escarpments, river cañons and "badland" areas, bare of
soil and vegetation and affording an immense stretch of
exposed rock for the explorer. Much of this area indeed
is desert, too far away from water to be profitably
searched under present conditions, or too far away from
railroads to allow of transportation of the finds at a
reasonable expense. Fossils are much more common in
certain parts of the region, and these localities have
mostly been explored more or less thoroughly. But the
field is far from being exhausted. New localities have
been found and old localities re-explored in recent
years, yielding specimens equal to or better than any
heretofore discovered. And as the railroad and the
automobile render new regions accessible, and the
erosion of the formations by wind and rain brings new
specimens to the surface, we may look forward to new
discoveries for many years to come.
In other continents, except in Europe, there has been
but little exploration for dinosaurs. Enough is known to
assure us that they will yield faunæ no less extensive
and remarkable than our own. We are in fact only
beginning to appreciate the vast extent and variety of
these records of a past world.
In a preceding chapter it was shown that the chief
formations in which dinosaur remains have been found
belong to the end of the Jurassic and the end of the
Cretacic periods. The Jurassic dinosaur formations skirt
the Rockies and outlying mountain ranges but are often
turned up on edge and poorly exposed, or barren of
fossils. The richest collecting ground is in the Laramie
Plains, between the Rockies and the Laramie range in
south-central Wyoming, but important finds have also
been made in Colorado and Utah. The Cretaceous Dinosaur
formations extend somewhat further out on the plains to
the eastward, and the best collecting regions thus far
explored are in eastern Wyoming, central Montana and in
Alberta, Canada. The First Discovery of
Dinosaurs in the West.
By Prof. S.W. Williston.
Most great discoveries are due rather to a state of
mind, if I may use such an expression, than to accident.
The discovery of the immense dinosaur deposits in the
Rocky Mountains in March, 1877, may truthfully be called
great, for nothing in paleontology has equalled it, and
that it was made by three observers simultaneously can
not be called purely an accident. These discoverers were
Mr. O. Lucas, then a school teacher, later clergyman;
Professor Arthur Lakes, then a teacher in the School of
Mines at Golden, Colorado; and Mr. William Reed, then a
section foreman of the Union Pacific Railroad at Como,
Wyoming, later the curator of paleontology of the
University of Wyoming—even as I write this, comes the
notice of his death,—the last. I knew them all, and the
last two were long intimate friends.
In the autumn of 1878 I wrote the following:[19]
"The history of their discovery (the dinosaurs) is
both interesting and remarkable. For years the beds
containing them had been studied by geologists of
experience, under the surveys of Hayden and King, but,
with the possible exception of the half of a caudal
vertebra, obtained by Hayden and described by Leidy as a
species of Poikilopleuron, not a single fragment
had been recognized. This is all the more remarkable
from the fact that in several of the localities I have
observed acres literally strewn with fragments of bones,
many of them extremely characteristic and so large as to
have taxed the strength of a strong man to lift them.
Three of the localities known to me are in the immediate
vicinity, if not upon the actual townsites of thriving
villages, and for years numerous fragments have been
collected by (or for) tourists and exhibited as fossil
wood. The quantities hitherto obtained, though
apparently so vast, are wholly unimportant in comparison
with those awaiting the researches of geologists
throughout the Rocky Mountain region. I doubt not that
many hundreds of tons will eventually be exhumed."
Rather a startling prophecy to make within eighteen
months of their discovery, but it was hardly
exaggerated.
It is impossible to say which of these three
observers actually made the first discovery of Jurassic
dinosaurs; whatever doubt there is is in favor of Mr.
Reed.
Professor Lakes, accompanied by his friend Mr. E.L.
Beckwith, an engineer, was, one day in March, 1877,
hunting along the "hogback" in the vicinity of Morrison,
Colorado, for fossil leaves in the Dakota Cretaceous
sandstone which caps the ridge, when he saw a large
block of sandstone with an enormous vertebra partly
imbedded in it. He discussed the nature of the fossil
with his friend (so he told me) and finally concluded
that it was a fossil bone. He had recently come from
England and had heard of Professor Phillips' discoveries
of similar dinosaurs there. He knew of Professor Marsh
of Yale from his recent discoveries of toothed birds in
the chalk of Kansas, and reported the find to him. As a
result, the specimen, rock and all, was shipped to him
by express at ten cents a pound! And Professor Marsh
immediately announced the discovery of Titanosaurus
(Atlantosaurus) immanis, a huge dinosaur
having a probable length of one hundred and fifteen feet
and unknown height. And Professor Lakes was immediately
set at work in the "Morrison quarry" near by, whence
comes the accepted name of these dinosaur beds in the
Rocky Mountains. Professor Lakes once showed me the
exact spot where he found his first specimen.
Mr. Lucas, teaching his first term of a country
school that spring in Garden Park near Cañon City, as an
amateur botanist was interested in the plants of the
vicinity. Rambling through the adjacent hills in search
of them, in March, 1877, he stumbled upon some fragments
of fossil bones in a little ravine not far from the
famous quarry later worked for Professor Marsh. He
recognized them as fossils and they greatly excited, not
only his curiosity, but the curiosity of the neighbors.
He had heard of the late Professor Cope and sent some of
the bones to him, who promptly labelled them
Camarasaurus supremus.
The announcement of these discoveries promptly
brought Mr. David Baldwin, Professor Marsh's collector
in New Mexico, to the scene. Only a few months
previously he had discovered fossil bones in the red
beds of New Mexico, the since famous Permian deposits.
He naturally explored the same beds at Cañon City,
immediately below the dinosaur deposits, and soon found
the still very problematical Hallopus skeleton,
at their very top, a specimen which after nearly forty
years remains unique of its kind.
A few years earlier Professor Marsh, on his way east
from the Tertiary deposits of western Wyoming, had
stopped at Como, Wyoming, to observe the strange
salamanders, or "fish with legs" as they were widely
known, so abundant in the lake at that place, about
whose transformations he later wrote a paper, perhaps
the only one on modern vertebrates that he ever
published. While he was there Mr. Carlin, the station
agent, showed him some fossil bone fragments, so Mr.
Reed told me, that they had picked up in the vicinity,
and about which Professor Marsh made some comments. But
he was so engrossed with the other discoveries he was
then making that he did not follow up the suggestion.
Had he done so the discovery of the "Jurassic Dinosaurs"
would have been made five years earlier.
Fig.
44.—The first dinosaur specimen found at Bone-Cabin
Quarry. Hind limb of
Diplodocus.
Mr. Reed, tramping over the famous Como hills after
game—he had been a professional hunter of game for the
construction camps of the Union Pacific Railroad—in the
winter and spring of 1877, observed some fossil bones
just south of the railway station that excited his
curiosity. But he and Mr. Carlin did not make their
discovery known to Professor Marsh till the following
autumn, and then under assumed names, fearing that they
would be robbed of their discovery. I was sent to Como
in November of 1877 from Cañon City. I got off the train
at the station after midnight, and enquired for the
nearest hotel—(the station comprised two houses only),
and where I could find Messrs. Smith and Robinson. I was
told that the section house was the only hotel in the
place and that these gentlemen lived in the country and
that there was no regular bus-line yet running to their
ranch. A freshly opened box of cigars, however, helped
clear up things, and I joined Mr. Reed the next day in
opening "Quarry No. 1" of the Como hills. Inasmuch as
the mercury in the thermometer during the next two
months seldom reached zero—upward I mean—the opening of
this famous deposit was made under difficulties. That so
much "head cheese," as we called it, was shipped to
Professor Marsh was more the fault of the weather and
his importunities than our carelessness. However, we
found some of the types of dinosaurs that have since
become famous.
I joined Professor Lakes at the Morrison quarry in
early September of 1877, and helped dig out some of the
bones of Atlantosaurus. A few weeks later I was
sent to Cañon City to help Professor Mudge, my old
teacher, and Mr. Felch, who had begun work there in the
famous "Marsh Quarry". It was here that we found the
type of Diplodocus.
The hind leg, pelvis and much of the tail of this
specimen lay in very orderly arrangement in the
sandstone near the edge of the quarry, but the bones
were broken into innumerable pieces. After consultation
we decided that they were too much broken to be worth
saving—and so most of them went over into the dump.
Sacrilege, doubtless, the modern collector will say, but
we did not know much about the modern methods of
collecting in those days, and moreover we were in too
much of a hurry to get the new discoveries to Yale
College to take much pains with them. I did observe that
the caudal vertebrae had very peculiar chevrons, unlike
others that I had seen, and so I attempted to save some
samples of them by pasting them up with thick layers of
paper. Had we only known of plaster-of-paris and burlap
the whole specimen might easily have been saved. Later,
when I reached New Haven, I took off the paper and
called Professor Marsh's attention to the strange
chevrons. And Diplodocus was the result.
My own connection with the discoveries of these old
dinosaurs continued only through the following summer,
in Wyoming, when we added the first mammals from the
hills immediately back of the station, and the types of
some of the smaller dinosaurs, and when we explored the
vicinity for other deposits, on Rock Creek and in the
Freeze Out Mountains.
How many tons of these fossils have since been dug up
from these deposits in the Rocky Mountains is beyond
computation. My prophecy of hundreds of tons has been
fulfilled; and they are preserved in many museums of the
world.
S.W. Williston.
The
Dinosaurs of the Bone-Cabin Quarry.[20]
By Henry Fairfield Osborn.
One is often asked the questions: "How do you find
fossils?" "How do you know where to look for them?" One
of the charms of the fossil-hunter's life is the
variety, the element of certainty combined with the
gambling element of chance. Like the prospector for
gold, the fossil-hunter may pass suddenly from the
extreme of dejection to the extreme of elation. Luck
comes in a great variety of ways: sometimes as the
result of prolonged and deliberate scientific search in
a region which is known to be fossiliferous; sometimes
in such a prosaic manner as the digging of a well. Among
discoveries of a highly suggestive, almost romantic
kind, perhaps none is more remarkable than the one I
shall now describe.
Discovery of the Great Dinosaur Quarry. In
central Wyoming, at the head of a "draw," or small
valley, not far from the Medicine Bow River, lies the
ruin of a small and unique building, which marks the
site of the greatest "find" of extinct animals made in a
single locality in any part of the world. The fortunate
fossil-hunter who stumbled on this site was Mr. Walter
Granger of the American Museum expedition of 1897.
In the spring of 1898, as I approached the hillock on
which the ruin stands, I observed, among the beautiful
flowers, the blooming cacti, and the dwarf bushes of the
desert, what were apparently numbers of dark-brown
boulders. On closer examination, it proved that there is
really not a single rock, hardly even a pebble, on this
hillock; all these apparent boulders are ponderous
fossils which have slowly accumulated or washed out on
the surface from a great dinosaur bed beneath. A Mexican
sheep-herder had collected some of these petrified bones
for the foundations of his cabin, the first ever built
of such strange materials. The excavation of a promising
outcrop was almost immediately rewarded by finding a
thigh-bone nearly six feet in length which sloped
downward into the earth, running into the lower leg and
finally into the foot, with all the respective parts
lying in the natural position as in life. This proved to
be the previously unknown hind limb of the great
dinosaur Diplodocus.
In this manner the "Bone-Cabin Quarry" was discovered
and christened. The total contents of the quarry are
represented in the diagram (not reprinted.) It has given
us, by dint of six successive years of hard work, the
materials for an almost complete revival of the life of
the Laramie region as it was in the days of the
dinosaurs. By the aid of workmen of every degree of
skill, by grace of the accumulated wisdom of the
nineteenth century, by the constructive imagination, by
the aid of the sculptor and the artist, we can summon
these living forms and the living environment from the
vasty deep of the past.
The Famous Como Bluffs. The circumstances
leading up to our discovery serve to introduce the
story. From 1890 to 1897 we had been steadily delving
into the history of the Age of Mammals, in deposits
dating from two hundred thousand to three million years
back, as we rudely estimate geological time. In the
course of seven years such substantial progress had been
made that I decided to push into the history of the Age
of Reptiles also, and, following the pioneers, Marsh and
Cope, to begin exploration in the period which at once
marks the dawn of mammalian life and the climax of the
evolution of the great amphibious dinosaurs.
In the spring of 1897 we accordingly began
exploration in the heart of the Laramie Plains, on the
Como Bluffs. On arrival, we found numbers of massive
bones strewn along the base of these bluffs, tumbled
from their stratum above, too weather-worn to attract
collectors, and serving only to remind one of the time
when these animals—the greatest, by far, that nature has
ever produced on land—were monarchs of the world.
Aroused from sleep on a clear evening in camp by the
heavy rumble of a passing Union Pacific
freight-train[21], I shall never forget my meditations
on the contrast between the imaginary picture of the
great Age of Dinosaurs, fertile in cycads and in a
wonderful variety of reptiles, and the present age of
steam, of heavy locomotives toiling through the
semi-arid and partly desert Laramie Plains.
So many animals had already been removed from these
bluffs that we were not very sanguine of finding more;
but after a fortnight our prospecting was rewarded by
finding parts of skeletons of the long-limbed dinosaur
Diplodocus and of the heavy-limbed dinosaur
Brontosaurus. The whole summer was occupied in
taking these animals out for shipment to the East, the
so-called "plaster method" of removal being applied with
the greatest success. Briefly, this is a surgical device
applied on a large scale for the "setting" of the
much-fractured bones of a fossilized skeleton. It
consists in setting great blocks of the skeleton, stone
and all, in a firm capsule of plaster subsequently
reinforced by great splints of wood, firmly drawn
together with wet rawhide. The object is to keep all the
fragments and splinters of bone together until it can
reach the skilful hands of the museum preparator.
The Rock Waves Connecting the Bluffs and the
Quarry. The Como Bluffs are about ten miles south of
the Bone-Cabin Quarry; between them is a broad stretch
of the Laramie Plains. The exposed bone layer in the two
localities is of the same age, and originally was a
continuous level stratum which may be designated as the
"dinosaur beds;" but this stratum, disturbed and crowded
by the uplifting of the not far-distant Laramie range of
mountains and the Freeze Out Hills, was thrown into a
number of great folds or rock waves. Large portions,
especially of the upfolds, or "anticlines," of the
waves, have been subsequently removed by erosion; the
edges of these upfolds have been exposed, thus
weathering out their fossilized contents, while
downfolds are still buried beneath the earth for the
explorers of coming centuries.
Therefore, as one rides across the country to-day
from the bluffs to the quarry, startling the intensely
modern fauna, the prong-horn antelopes, jack-rabbits,
and sage-chickens, he is passing over a vast graveyard
which has been profoundly folded and otherwise shaken up
and disturbed. Sometimes one finds the bone layer
removed entirely, sometimes horizontal, sometimes
oblique, and again dipping directly into the heart of
the earth. This layer (dinosaur beds) is not more than
two hundred and seventy-four feet in thickness, and is
altogether of fresh-water origin; but as a proof of the
oscillations of the earth-level both before and after
this great thin sheet of fresh-water rock was so widely
spread, there are evidences of the previous invasion of
the sea (ichthyosaur beds) and of the subsequent
invasion of the sea (mosasaur beds) in the whole Rocky
Mountain region.
In traveling through the West, when once one has
grasped the idea of continental oscillation, or
submergence and emergence of the land, of the sequence
of the marine and fresh-water deposits in laying down
these pages of earth-history, he will know exactly where
to look for this wonderful layer-bed of the giant
dinosaurs; he will find that, owing to the uplift of
various mountain-ranges, it outcrops along the entire
eastern face of the Rockies, around the Black Hills, and
in all parts of the Laramie Plains; it yields dinosaur
bones everywhere, but by no means so profusely or so
perfectly as in the two famous localities we are
describing.
How the Skeletons Lie in the Bluffs and Quarry.
At the bluffs single animals lie from twenty to one
hundred feet apart; one rarely finds a whole skeleton,
such as that of Marsh's Brontosaurus excelsus,
the finest specimen ever secured here, which is now one
of the treasures of the Yale museum. More frequently a
half or a third of a skeleton lies together.
Fig. 45.—Collecting
Dinosaurs at Bone-Cabin Quarry.
a. The overlying soil and rocks are loosened
with a pick and removed with team and scraper
down to the fossil layer.
b. The fossil layer is carefully prospected with
small tools, chisels, awls and whisk brooms
exposing the bones as they lie in the rocks.
c. The blocks containing the fossils are
channelled around, plastered over top and sides,
undercut and carefully turned over and the under
side trimmed and plastered.
d. The blocks are then packed in boxes or crates
with hay or any other available packing
material.
e. Boxes are loaded on wagons and hauled across
country to the railroad.
f. Boxes are finally loaded on cars and shipped
through to New York City.
In the Bone-Cabin Quarry, on the other hand, we came
across a veritable Noah's-ark deposit, a perfect museum
of all the animals of the period. Here are the largest
of the giant dinosaurs closely mingled with the remains
of the smaller but powerful carnivorous dinosaurs which
preyed upon them, also those of the slow and
heavy-moving armored dinosaurs of the period, as well as
of the lightest and most bird-like of the dinosaurs.
Finely rounded, complete limbs from eight to ten feet in
length are found, especially those of the carnivorous
dinosaurs, perfect even to the sharply pointed and
recurved tips of their toes. Other limbs and bones are
so crushed and distorted by pressure that it is not
worth while removing them. Sixteen series of vertebræ
were found strung together; among these were eight long
strings of tail-bones. The occurrence of these tails is
less surprising when we come to study the important and
varied functions of the tail in these animals, and the
consequent connection of the tail-bones by means of
stout tendons and ligaments which held them together for
a long period after death. Skulls are fragile and rare
in the quarry, because in every one of these big
skeletons there were no fewer than ninety distinct bones
which exceeded the head in size, the excess in most
cases being enormous.
The bluffs appear to represent the region of an
ancient shoreline, such conditions as we have depicted
in the restoration of Brontosaurus (fig. 22)—the
sloping banks of a muddy estuary or of a lagoon, either
bare tidal flats or covered with vegetation. Evidently
the dinosaurs were buried at or near the spot where they
perished.
The Bone-Cabin Quarry deposit represents entirely
different conditions. The theory that it is the
accumulation of a flood is, in my opinion, improbable,
because a flood would tend to bring entire skeletons
down together, distribute them widely, and bury them
rapidly. A more likely theory is that this was the area
of an old river-bar, which in its shallow waters
arrested the more or less decomposed and scattered
carcasses which had slowly drifted down-stream toward
it, including a great variety of dinosaurs, crocodiles,
and turtles, collected from many points up-stream. Thus
were brought together the animals of a whole region, a
fact which vastly enhances the interest of this deposit.
The Giant Herbivorous Dinosaurs. By far the
most imposing of these animals are those which may be
popularly designated as the great or giant dinosaurs.
The name, derived from deinos terrible, and
sauros lizard, refers to the fact that they appeared
externally like enormous lizards, with very long limbs,
necks, and tails. They were actually remotely related to
the tuatera lizard of New Zealand, and still more
remotely to the true lizards.
No land animals have ever approached these giant
dinosaurs in size, and naturally the first point of
interest is the architecture of the skeleton. The
backbone is indeed a marvel. The fitness of the
construction consists, like that of the American
truss-bridge, in attaining the maximum of strength with
the minimum of weight. It is brought about by dispensing
with every cubic millimeter of bone which can be spared
without weakening the vertebræ for the various stresses
and strains to which they were subjected, and these must
have been tremendous in an animal from sixty to seventy
feet in length. The bodies of the vertebræ are of
hour-glass shape, with great lateral and interior
cavities; the arches are constructed on the T-iron
principle of the modern bridge-builder, the back spines
are tubular, the interior is spongy, these devices being
employed in great variety, and constituting a mechanical
triumph of size, lightness, and strength combined.
Comparing a great chambered dinosaurian (Camarasaurus)
vertebra (see above) with the weight per cubic inch of
an ostrich vertebra, we reach the astonishing conclusion
that it weighed only twenty-one pounds, or half the
weight of a whale vertebra of the same bulk. The
skeleton of a whale seventy-four feet in length has
recently been found by Mr. F.A. Lucas of the Brooklyn
Museum to weigh seventeen thousand nine hundred and
twenty pounds. The skeleton of a dinosaur of the same
length may be roughly estimated as not exceeding ten
thousand pounds.
Proofs of Rapid Movements on Land. Lightness
of skeleton is a walking or running or flying
adaptation, and not at all a swimming one; a swimming
animal needs gravity in its skeleton, because sufficient
buoyancy in the water is always afforded by the lungs
and soft tissues of the body. The extraordinary
lightness of these dinosaur vertebræ may therefore be
put forward as proof of supreme fitness for the
propulsion of an enormous frame during occasional
incursions upon land[22]. There are additional facts
which point to land progression, such as the point in
the tail where the flexible structure suddenly becomes
rigid, as shown in the diagram of vertebræ below; the
component joints are so solid and flattened on the lower
surface that they seem to demonstrate fitness to support
partly the body in a tripodal position like that of a
kangaroo. I have therefore hazarded the view that even
some of these enormous dinosaurs were capable of raising
themselves on their hind limbs, lightly resting on the
middle portion of the tail. In such a position the
animal would have been capable not only of browsing
among the higher branches of trees, but of defending
itself against the carnivorous dinosaurs by using its
relatively short but heavy front limbs to ward off
attacks.
There are also indications of aquatic habits in some
of the giant dinosaurs which render it probable that a
considerable part of their life was led in the water.
One of these indications is the backward position of the
nostrils. Many, but not all, water-living mammals and
reptiles have the nostrils on top of the head, in order
to breathe more readily when the head is partly
immersed. Another fact of note, although perhaps less
conclusive, is the fitness of the tail for use while
moving about in the water, if not in rapid swimming.
The great tail, measuring from twenty-eight to thirty
feet, was one of the most remarkable structures in these
animals, and undoubtedly served a great variety of
purposes, propelling while in the water, balancing and
supporting and defending while on land. In Diplodocus
it was most perfectly developed from its muscular base
to its delicate and whip-like tip, perhaps for all these
functions.
The Three Kinds of Giant Dinosaurs. It is very
remarkable that three distinct kinds of these great
dinosaurs lived at the same time in the same general
region, as proved by the fact that their remains are
freely commingled in the quarry.
What were the differences in food and habits, in
structure and in gait, which prevented that direct and
active competition between like types in the struggle
for existence which in the course of nature always leads
to the extermination of one or the other type? In the
last three years we have discovered very considerable
differences of structure which make it appear that these
animals, while of the same or nearly the same linear
dimensions, did not enter into direct competition either
for food or for territory.
The dinosaur named Diplodocus by Marsh is the
most completely known of the three. Our very first
discovery in the Bone-Cabin Quarry gave us the hint that
Diplodocus was distinguished by relatively long,
slender limbs, and that it may be popularly known as the
"long-limbed dinosaur." The great skeleton found in the
Como Bluffs enabled me to restore for the first time the
posterior half of one of these animals estimated as
sixty feet in length, the hips and tail especially being
in a perfect state of preservation. A larger animal,
nearer seventy feet in length, including the anterior
half of the body, and still more complete, was
discovered about ten miles north of the quarry, and is
now in the Carnegie Museum in Pittsburg. Combined, these
two animals have furnished a complete knowledge of the
great bony frame. The head is only two feet long, and
is, therefore, small out of all proportion to the great
body. The neck measures twenty-one feet four inches, and
is by far the longest and largest neck known in any
animal living or extinct. The back is relatively very
short, measuring ten feet eight inches. The vertebræ of
the hip measure two feet and three inches. The tail
measures from thirty-two to forty feet. We thus obtain,
as a moderate estimate of the total length of the
animal, sixty-eight to seventy feet. The restored
skeleton, published by Mr. J.B. Hatcher in July, 1901,
and partly embodying our results, gave to science the
first really accurate knowledge of the length of these
animals, which hitherto had been greatly overestimated.
The highest point in the body was above the hips; here
in fact, was the center of power and motion, because, as
observed above, the tail fairly balanced the anterior
part of the body.
The restoration by Mr. Knight is drawn from a very
careful model made under my direction, in which the
proportions of the animal are precisely estimated. It
is, I think, accurate—for a restoration—as well as
interesting and up-to-date. These restorations are the
"working hypotheses" of our science; they express the
present state of our knowledge, and, being subject to
modification by future discoveries, are liable to
constant change.
By contrast, the second type of giant dinosaur, the
Brontosaurus, or "thunder saurian" of Marsh, as
shown in the restoration (fig. 22), was far more massive
in structure and relatively shorter in body. Five more
or less complete skeletons are now to be seen in the
Yale, American, Carnegie, and Field Columbian museums.
In 1898 we discovered in the bluffs, about three miles
west of the Bone-Cabin Quarry, the largest of these
animals which has yet been found; it was worked out with
great care and is now being restored and mounted
complete in the American Museum. The thigh-bone is
enormous, measuring five feet eight inches in length,
and is relatively of greater mass than that of
Diplodocus. The neck, chest, hips, and tail are
correspondingly massive. The neck is relatively shorter,
however, measuring eighteen feet, while in Diplodocus
it measures over twenty-one feet. The total length of
this massive specimen is estimated at sixty-three feet,
or from six to eight feet less than the largest
"long-limbed" dinosaur. The height of the skeleton at
the hips is fifteen feet. There is less direct evidence
that the "thunder saurian" had the power of raising its
fore quarters in the air than in the case of the
"light-limbed saurian," because no bend or supporting
point in the tail has been distinctly observed.
The third type of giant dinosaur is the less
completely known "chambered saurian," the
Camarasaurus of Cope or Morosaurus of Marsh,
an animal more quadrupedal in gait or walking more
habitually on all fours, like the great Cetiosaurus,
or "whale saurian," discovered near Oxford, England.
With its shorter tail and heavier fore limbs, it is
still less probable that this animal had the power of
raising the anterior part of its body from the ground.
Of a related type, perhaps, is the largest dinosaur ever
found; this is the Brachiosaurus, limb-bones of
which were discovered in central Colorado in 1901 and
are now preserved in the Field Columbian Museum of
Chicago. Its thigh-bone is six feet eight inches in
length, and its upper arm-bone, or humerus, is even
slightly longer.
Feeding Habits of the Giant Dinosaurs. We
still have to solve one of the most perplexing problems
of fossil physiology; how did the very small head,
provided with light jaws, slender and spoon-shaped teeth
confined to the anterior region, suffice to provide food
for these monsters? I have advanced the idea that the
food of Diplodocus consisted of some very
abundant and nutritious species of water-plant; that the
clawed feet were used in uprooting such plants, while
the delicate anterior teeth were employed only for
drawing them out of the water; that the plants were
drawn down the throat in large quantities without
mastication, since there were no grinding or back teeth
whatever in this animal. Unfortunately for this theory,
it is now found that the front feet were not provided
with many claws, there being only a single claw on the
inner side. Nevertheless by some such means as this,
these enormous animals could have obtained sufficient
food in the water to support their great bulk.
The Carnivorous Dinosaurs. Mingling with the
larger bones in the quarry are the more or less perfect
remains of swamp turtles, of dwarf crocodiles, of the
entirely different group of plated dinosaurs, or
Stegosauria, but especially of two entirely distinct
kinds of large and small flesh-eating dinosaurs. The
latter rounded out and gave variety to the dinosaur
society, and there is no doubt that they served the
savage but useful purpose, rendered familiar by the
doctrine of Malthus, of checking overpopulation. These
fierce animals had the same remote ancestry as the giant
dinosaurs, but had gradually acquired entirely different
habits and appearance.
Far inferior in size, they were superior in agility,
exclusively bipedal, with very long, powerful hind
limbs, upon which they advanced by running or springing,
and with short fore limbs, the exact uses of which are
difficult to ascertain. Both hands and feet were
provided with powerful tearing claws. On the hind foot
is the back claw, so characteristic of the birds, which
during the Triassic period left its faint impression
almost everywhere in the famous Connecticut valley
imprints of these animals. That the fore limb and hand
were of some distinct use is proved by the enormous size
of the thumb-claw; while the hand may not have conveyed
food to the mouth, it may have served to seize and tear
the prey. As to the actual pose in feeding, there can be
little doubt as to its general similarity to that of the
Raptores among the birds, as suggested to me by
Dr. Wortman (see fig. 10); one of the hind feet rested
on the prey, the other upon the ground, the body being
further balanced or supported by the vertebræ of the
tail. The animal was thus in a position to apply its
teeth and exert all the power of its very powerful
arched back in tearing off its food. That the gristle of
the bone or cartilage was very palatable is attested not
only by the toothmarks upon these bones, but by many
similar markings found in the Bone-Cabin Quarry.
The Bird-Catching Dinosaur. Of all the
bird-like dinosaurs which have been discovered, none
possesses greater similitude to the birds than the gem
of the quarry, the little animal about seven feet in
length which we have named Ornitholestes, or the
"bird-catching dinosaur." It was a marvel of speed,
agility, and delicacy of construction. Externally its
bones are simple and solid-looking, but as a matter of
fact they are mere shells, the walls being hardly
thicker than paper, the entire interior of the bone
having been removed by the action of the same marvelous
law of adaptation which sculptured the vertebræ of its
huge contemporaries. There is no evidence, however, that
these hollow bones were filled with air from the lungs,
as in the case of the bones of birds. The foot is
bird-like; the hand is still more so; in fact, no
dinosaur hand has ever before been found which so
closely mimics that of a bird in the great elongation of
the first or index-finger, in the abbreviation of the
thumb and middle finger, and in the reduction of the
ring-finger. These fingers, with sharp claws, were not
strong enough for climbing, and the only special fitness
we have been able to imagine is that they were used for
the grasping of a light and agile prey (see figs. 17,
18.)
Another reason for the venture of designating this
animal as the "bird-catcher" is that the Jurassic birds
(not thus far discovered in America, but known from the
Archæopteryx of Germany) were not so active or
such strong fliers as existing birds; in fact, they were
not unlike the little dinosaur itself. They were
toothed, long-tailed, short-armed, the body was
feathered instead of scaled; they rose slowly from the
ground. This renders it probable that they were the prey
of the smaller pneumatic-built dinosaurs such as the
present animal.
This hypothetical bird-catcher seems to have been
designed to spring upon a delicately built prey, the
structure being the very antipode of that of the large
carnivorous dinosaurs. A difficulty in the bird-catching
theory, namely, that the teeth are not as sharp as one
would expect to find them in a flesh-eater, is somewhat
offset by the similarity of the teeth to those of the
bird-eating monitor lizards (Varanus), which are
not especially sharp.
The Great Yield of the Quarry. Our
explorations in the quarry began in the spring of 1898,
and have continued ever since during favorable weather.
The total area explored at the close of the sixth year
was seven thousand two hundred and fifty square feet.
Not one of the twelve-foot squares into which the quarry
was plotted lacked its covering of bones, and in some
cases the bones were two or three deep. Each year we
have expected to come to the end of this great deposit,
but it still yields a large return, although we have
reason to believe that we have exhausted the richest
portions.
We have taken up four hundred and eighty-three parts
of animals, some of which may belong to the same
individuals. These were packed in two hundred and
seventy-five boxes, representing a gross weight of
nearly one hundred thousand pounds. Reckoning from the
number of thigh-bones, we reach, as a rough estimate of
the total, seventy-three animals of the following kinds:
giant herbivorous dinosaurs, 44; plated herbivorous
dinosaurs, or stegosaurs, 3; iguanodonts or smaller
herbivorous dinosaurs, 4; large carnivorous dinosaurs,
6; small carnivorous dinosaurs, 3; crocodiles, 4;
turtles, 5. But this represents only a part of the whole
deposit, which we know to be of twice the extent already
explored, and these figures do not include the bones
which were partly washed out and used in the
construction of the Bone-Cabin. The grand total would
probably include parts of over one hundred giant
dinosaurs.
The Struggle for Existence Among the Dinosaurs.
Never in the whole history of the world as we now know
it have there been such remarkable land scenes as were
presented when the reign of these titanic reptiles was
at its climax. It was also the prevailing life-picture
of England, Germany, South America, and India. We can
imagine herds of these creatures from fifty to eighty
feet in length, with limbs and gait analogous to those
of gigantic elephants, but with bodies extending through
the long, flexible, and tapering necks into the
diminutive heads, and reaching back into the equally
long and still more tapering tails. The four or five
varieties which existed together were each fitted to
some special mode of life; some living more exclusively
on land, others for longer periods in the water.
The competition for existence was not only with the
great carnivorous dinosaurs, but with other kinds of
herbivorous dinosaurs (the iguanodonts), which had much
smaller bodies to sustain and a much superior tooth
mechanism for the taking of food.
The cutting off of this giant dinosaur dynasty was
nearly if not quite simultaneous the world over. The
explanation which is deducible from similar catastrophes
to other large types of animals is that a very large
frame, with a limited and specialized set of teeth
fitted only to a certain special food, is a dangerous
combination of characters. Such a monster organism is no
longer adaptable; any serious change of conditions which
would tend to eliminate the special food would also
eliminate these great animals as a necessary
consequence.
Fig.
46.—Badlands on the Red Deer River in Alberta. This
region is the richest known collecting ground for
cretacic dinosaurs.
There is an entirely different class of explanations,
however, to be considered, which are consistent both
with the continued fitness of structure of the giant
dinosaurs themselves and with the survival of their
especial food; such, for example, as the introduction of
a new enemy more deadly even than the great
carnivorous dinosaurs. Among such theories the most
ingenious is that of the late Professor Cope, who
suggested that some of the small, inoffensive, and
inconspicuous forms of Jurassic mammals, of the size of
the shrew and the hedgehog, contracted the habit of
seeking out the nests of these dinosaurs, gnawing
through the shells of their eggs, and thus destroying
the young. The appearance, or evolution, of any
egg-destroying animals, whether reptiles or mammals,
which could attack this great race at such a defenseless
point would be rapidly followed by its extinction. We
must accordingly be on the alert for all possible
theories of extinction; and these theories themselves
will fall under the universal principle of the survival
of the fittest until we approximate or actually hit upon
the truth.
Fossil Hunting by Boat in Canada.
By Barnum Brown.
"How do you know where to look for fossils?" is a
common question. In general it may be answered that the
surface of North America has been pretty well explored
by government surveys and scientific expeditions and the
geologic age of the larger areas determined. Most
important in determining the geologic sequence of the
earth's strata are the fossil remains of animal and
plant life. A grouping of distinct species of fossils
correlated with stratigraphic characters in the rocks
determines these subdivisions. When a collection of
fossils is desired to represent a certain period,
exploring parties are sent to these known areas.
Sometimes however, chance information leads up to most
important discoveries, such as resulted from the work of
the past two seasons in Alberta, Canada.
A visitor to the Museum, Mr. J.L. Wagner, while
examining our mineral collections saw the large bones in
the Reptile Hall and remarked to the Curator of
Mineralogy that he had seen many similar bones near his
ranch in the Red Deer Cañon of Alberta. After talking
some time an invitation was extended to the writer to
visit his home and prospect the cañon. Accordingly in
the fall of 1909 a preliminary trip was made to the
locality.
From Didsbury, a little town north of Calgary, the
writer drove eastward ninety miles to the Red Deer River
through a portion of the newly opened grain belt of
Alberta, destined in the near future to produce a large
part of the world's bread. Near the railroad the land is
mostly under cultivation and comfortable homes and
bountiful grain fields testify to the rich nature of the
soil. A few miles eastward the brushland gives way to a
level expanse of grass-covered prairie dotted here and
there by large and small lakes probably of glacial
origin. Mile after mile the road follows section lines
and one is rarely out of sight of the house of some
"homesteader." It is through this level farm land that
the Red Deer River wends its way flowing through a cañon
far below the surface. Near Wagner's ranch the cañon was
prospected and so many bones found that it appeared most
desirable to do extended searching along the river.
Usually fossils are found in "bad lands," where
extensive areas are denuded of grass and the surface
eroded into hills and ravines. A camp is located near
some spring or stream and collectors ride or walk over
miles of these exposures in each direction till the
region is thoroughly explored. Quite different are
conditions on the Red Deer River. Cutting through the
prairie land the river had formed a cañon two to five
hundred feet deep and rarely more than a mile wide at
the top. In places the walls are nearly perpendicular
and the river winds in its narrow valley, touching one
side then crossing to the other so that it is impossible
to follow up or down its course any great distance even
on horseback.
It was evident that the most feasible way to work
these banks was from a boat; consequently in the summer
of 1910 our party proceeded to the town of Red Deer,
where the Calgary-Edmonton railroad crosses the river.
There a flatboat, twelve by thirty feet in dimension,
was constructed on lines similar to a western ferry
boat, having a carrying capacity of eight tons with a
twenty-two foot oar at each end to direct its course.
The rapid current averaging about four miles per hour
precluded any thought of going up stream in a large
boat, so it was constructed on lines sufficiently
generous to form a living boat as well as to carry the
season's collection of fossils.
Supplied with a season's provisions, lumber for
boxes, and plaster for encasing bones, we began our
fossil cruise down a cañon which once echoed songs of
the Bois brulé, for this was at one time the fur
territory of the great Hudson Bay Company.
Fig. 47.—American Museum Expedition on the Red Deer
River. Fossils secured along the banks were packed
and loaded aboard the large scow and floated down
the river to the railway station.
No more interesting or instructive journey has ever
been taken by the writer. High up on the plateau,
buildings and haystacks proclaim a well-settled country,
but habitations are rarely seen from the river and for
miles we floated through picturesque solitude unbroken
save by the roar of the rapids.
Especially characteristic of this cañon are the
slides where the current setting against the bank has
undermined it until a mountain of earth slips into the
river, in some cases almost choking its course. A
continual sorting thus goes on, the finer material being
carried away while the boulders are left as barriers
forming slow moving reaches of calm water and stretches
of rapids difficult to navigate during low water. In one
of these slides we found several small mammal jaws and
teeth not known before from Canada, associated with
fossil clam shells of Eocene age.
The long midsummer days in latitude 52° gave many
working hours, but with frequent stops to prospect the
banks we rarely floated more than twenty miles per day.
An occasional flock of ducks and geese were disturbed as
our boat approached and bank beaver houses were
frequently passed, but few of the animals were seen
during the daytime. Tying the boat to a tree at night we
would go ashore to camp among the trees where after
dinner pipes were smoked in the glow of a great camp
fire. Only a fossil hunter or a desert traveler can
fully appreciate the luxury of abundant wood and running
water. In the stillness of the night the underworld was
alive and many little feet rustled the leaves where
daylight disclosed no sound. Then the beaver and muskrat
swam up to investigate this new intruder, while from the
tree-tops came the constant query, "Who! Who!"
For seventy miles the country is thickly wooded with
pine and poplar, the stately spruce trees silhouetted
against the sky adding a charm to the ever changing
scene. Nature has also been kind to the treeless regions
beyond, for underneath the fertile prairie, veins of
good lignite coal of varying thickness are successively
cut by the river. In many places these are worked in the
river banks during winter. One vein of excellent quality
is eighteen feet thick, although usually they are much
thinner. The government right has been taken to mine
most of this coal outcropping along the river.
Fig. 48.—Locality of Ankylosaurus skull in Edmonton
formation in Red Deer River. The skull is in the
rock just above the pick, about the center of the
photograph.
Along the upper portion of the stream are banks of
Eocene age, from which shells and mammal jaws were
secured, but near the town of Content where the river
bends southward, a new series of rocks appeared and in
these our search was rewarded by finding dinosaur bones
similar to those seen at Wagner's ranch. Specimens were
found in increasing numbers as we continued our journey,
and progress down the river was necessarily much slower.
Frequently the boat would be tied up a week or more at
one camp while we searched the banks, examining the
cliffs layer by layer that no fossil might escape
observation. With the little dingey the opposite side of
the river was reached so that both sides were covered at
the same time from one camp. As soon as a mile or more
had been prospected or a new specimen secured, the boat
was dropped down to a new convenient anchorage. Box
after box was added to the collection till scarcely a
cubit's space remained unoccupied on board our fossil
ark.
Where prairie badlands are eroded in innumerable
buttes and ravines it is always doubtful if one has seen
all exposures, so there was peculiar satisfaction in
making a thorough search of these river banks knowing
that few if any fossils had escaped observation. On
account of the heavy rainfall and frequent sliding of
banks new fossils are exposed every season so that in a
few years these same banks can again be explored
profitably. This river will become as classic hunting
ground for reptile remains as the Badlands of South
Dakota are for mammals.
Although the summer days are long in this latitude
the season is short and thousands of geese flying
southward foretell the early winter. Where the
temperature is not infrequently forty to sixty degrees
below zero in winter, it is difficult to think of a time
when a warm climate could have prevailed, yet such
condition is indicated by the fossil plants.
When the weather became too cold to work with
plaster, the fossils were shipped from a branch railroad
forty-five miles distant, the camp material was stored
for the winter and with block and tackle the big boat
was hauled up on shore above the reach of high water.
In the summer of 1911 the boat was recalked and again
launched when we continued our search from the point at
which work closed the previous year. During the summer
we were visited by the Museum's President, Prof. Henry
Fairfield Osborn, and one of the Trustees, Mr. Madison
Grant. A canoeing trip, one of great interest and
pleasure, was taken with our visitors covering two
hundred and fifty miles down the river from the town of
Red Deer, during which valuable material was added to
the collection and important geological data secured.
As a result of the Canadian work the Museum is
enriched by a magnificent collection of Cretaceous
fossils some of which are new to science.
FOOTNOTES:
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