Samuel Wendell Williston.

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spot, saw with extreme pleasure the indication of a magnificent specimen; he
directed the operations of the men, so that they worked out the block without



SQUAMATA 149

injury to the fossil, and he then, by degrees, cleared away the yielding matrix
and exposed the extraordinary jaws and teeth, which have since been the sub-
ject of so many drawings, descriptions, and discussions. This fine specimen
which Dr. Hofmann had transported with so much satisfaction to his collection,
soon became, however, a source of much chagrin to him. Dr. Goddin, one of
the canons of Maestricht, who owned the surface of the soil beneath which was
the quarry whence the fossil was obtained, when the fame of the fossil reached
his ears, pleaded certain feudal rights in support of his claim to it. Hofmann
resisted and the canon went to law. The whole chapter supported their rever-
end brother, and the decree ultimately went against the poor surgeon, who
lost both the specimen and his money, for he was made to pay the costs of the
action. The canon, leaving all remorse to the judges who pronounced the
iniquitous sentence, became the happy and contented possessor of this unique
example of its kind. [Translation by Leidy.]

But the canon was ultimately despoiled of his ill-gotten treasure.
At the siege of Maestricht in 1795, the famous skull to which Hof-
mann had devoted so much anxious thought and labor, fell into
the hands of the French and was carried off as one of the spoils
of war. So widely celebrated had the specimen become during
the fifteen years which had elapsed since its discovery, through
the writings of several noted scientific men, that the French general
commanded his artillerists to spare the house in which it was known
to be. The canon, however, shrewdly suspecting that such an
unexpected and extraordinary mark of favor was not for his own
sake but rather for the sake of the famous fossil, had it removed
and carefully hidden in a house in the city. After the capitula-
tion of Maestricht the eagerly sought-for fossil was not to be found,
and the offer of a reward of six hundred bottles of wine, so the
story goes, was made for its recovery. So tempting was the offer
that, ere long, it was brought in triumph to the house of St. Faujas
de Fond, by a half-dozen grenadiers, whence it was later trans-
ferred to Paris, where it now is.

We may well sympathize with Dr. Hofmann in the loss of his
cherished specimen, since, had it not been for his zeal, money, and
labor, it would never have escaped the usual fate of such things-
complete destruction. But we must remember that St. Faujas
de Fond, the recorder of this history, was a Frenchman, and some-
what interested in robbing the reverend canon of it; possibly there
is another side of the story which has never been told.



150 WATER REPTILES OF THE PAST AND PRESENT

After peace was declared, one has regretfully to add that the
canon, not Dr. Hofmann, was reimbursed for it, or so it is said.
Cuvier rather naively says that it was ceded to the Garden of
Plants of Paris, perhaps in the way that many other things are
ceded to the conqueror in time of war. The specimen is really
a good one, even when compared with many found in recent years,
and there is little wonder that the cupidity of St. Fond was incited
by it. Casts of it are now or have been in nearly every noted
museum of the world, and pictures of it illustrated nearly every
textbook of geology published during the first three-quarters of the
past century. It had been the subject of considerable contro-
versy even before it came into the hands of Cuvier. Peter Camper
figured and described the skull as that of a whale or "breathing
fish"; while St. Fond himself later called it a crocodile. Crocodile
or alligator skeletons were rare in those days, and St. Fond
made a special trip to the British Museum to study one. But it
was really Adrian Camper, a son of Peter Camper, who deserves
the credit, so often wrongly ascribed to Cuvier, for the recognition
of the true nature of the fossil. He insisted that the animal was
a lizard allied to the living monitors, an opinion which it will
be seen has finally been proved to be correct within very recent
years.

In 1808 this famous skull, and all other known remains of a
similar nature, came under the observation of Cuvier, the renowned
French naturalist and paleontologist, who confirmed the views of
Adrian Camper. He fully described and figured all the known
parts of the skeleton that had later come to light, calling the animal
the great lizard of the Meuse, the river near which Hofmann's
specimen was found. Conybeare, a well-known paleontologist
of England, some years later formally christened it Mosasaurus,
a transliteration of Cuvier's phrase, from the Latin Mosa, for
Meuse, and saurus, a lizard. For more than half a century Cuvier's
figure of the skull of the original specimen appeared in works
on geology over the name Mosasaurus hofmanni, or Mosasaurus
camperi. One could wish that the former name for the species
might prevail, in recognition of the zealous doctor who was so
shabbily treated in his possession of the specimen.



SQUAMATA



For some years the few specimens discovered
by Drouin and Hofmann were all that were
known of the mosasaurs. A few others of
related forms were discovered in England, and
some were reported from New Jersey by early
explorers, but there was little published about
the mosasaurs till 1843, when Dr. August Gold-
fuss, a noted German paleontologist, described
and beautifully figured an excellent specimen
from the United States. This specimen also
had a rather eventful history. It was dis-
covered early in the fourth decade by Major
O'Fallen, an Indian agent, near the Great Bend
of the Missouri River, whence it was trans-
ported by him to St. Louis and placed in his
garden as a curiosity. It happened that Prince
Maximilian of Wied, the famous naturalist, in
his travels through the United States, saw the
specimen and secured it, taking it to Germany
on his return. He presented it to the Museum
of Haarlem where Goldfuss saw and described
it. Rather oddly, this specimen was of a
species closely allied to the original one of
Maestricht, a species which has since only
rarely been found. It was called Mosasaurus
maximiliani by Goldfuss, though some time
previously, it has since been found, some frag-
ments of the same species were described by
Harlan, an American author, under the name
Ichthyosaurus missouriensis. Goldfuss' paper
was strangely overlooked by subsequent
writers, and it was not till the discovery of
numerous remains of mosasaurs by Leidy,
Cope, and Marsh in the chalk of western
Kansas, nearly thirty years later, that much
was added to the world's knowledge of these
strange reptiles.



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152 WATER REPTILES OF THE PAST AND PRESENT

Perhaps nowhere in the world are the fossil remains of marine
animals more abundantly and better preserved than in these
famous chalk deposits of Kansas. The exposures are of great
extent — hundreds of square miles — and the fossil treasures they
contain seem inexhaustible. Long-continued explorations by col-
lectors have brought to light thousands of specimens of these
swimming lizards, some of them of extraordinary completeness
and perfect preservation, so complete and so perfect that there is
scarcely anything concerning the mosasaurs which one might hope
to learn from their fossil remains that has not been yielded up by
these many specimens. The complete structure and relations of
all parts of the skeleton, impressions of the bodies made in the soft
sediments before decomposition had occurred, the character of
their food, the nature of the skin covering, and even some of the
color markings of the living animals have all been determined with
certainty. Not only from Kansas, but also from many other
parts of the world, have remains of these animals been discovered,
until now it may truthfully be said that no other group of extinct
reptiles is better represented by known fossil remains than the
mosasaurs. From England, Belgium, Russia, and France in
Europe; from New Jersey, Georgia, Alabama, Mississippi, Texas,
New Mexico, Colorado, Kansas, Nebraska, the Dakotas, Wyo-
ming, and other places in the United States; from New Zealand
and South America they have been obtained in greater or less
abundance and perfection.

Their geological history is relatively brief, notwithstanding
their wide distribution over the earth in such great numbers and
diversity. The earliest are known from near the beginning of the
Upper Cretaceous of New Zealand, whence it is believed by some
that they migrated to other parts of the world, appearing in
North America some time later. They reached their culmination in
size, numbers, and variety very soon, and then disappeared forever
before the close of Cretaceous time. The largest complete speci-
men of a mosasaur known measures a little more than thirty feet
in length, but incomplete skeletons of others indicate a maximum
length of about forty feet. The skulls of the largest species are
about five feet long. The smallest known adult skeletons are



SQUAMATA



J 53



scarcely eight feet in length. There are now known at the present
time seven or eight genera of three distinct types, all belonging
to one family, the Mosasauridae, including about twenty-five
known species. While a few of the genera are widely distributed
over the earth, the species are all of restricted range, indicating,
perhaps, non-migratory habits.

The adaptation of the mosasaurs to an aquatic life was very
complete, though perhaps not so complete as was that of the
ichthyosaurs. The skull is flattened, narrow, and more or less
elongate, but large in proportion to the re-
mainder of the skeleton — nearly one-sixth of
the entire length; that relative size doubtless
is indicative of very predaceous and pugna-
cious habits. The teeth in the typical forms
are numerous, strong, and sharp, conical in
shape, and recurved. Not only are there
numerous teeth in both the upper and lower
jaws, but there are also two rows of strong
teeth implanted in the back part of the
palate, upon bones called pterygoids, the use
of which will be understood later. The teeth
were inserted on large, tumid, bony bases,
rather loosely attached in shallow pits or
alveoli, unlike the teeth of all modern lizards.
Such a mode of attachment of the teeth
doubtless had some relation to the habits of
the animals concerning which we are not

quite clear. They were easily dislodged, and, in consequence, of
very unequal size, some full grown, some small, and others just
appearing above the surface of the gums in the living animals.
The frequent loss of teeth and their constant and easy replace-
ment by new ones is a peculiarity of predaceous reptiles, thereby
insuring their best functional use.

The external nostrils, of large size, were situated at a consider-
able distance back of the end of the snout, but not nearly so far
back or so near the eyes as were the nostrils of the ichthyosaurs,
plesiosaurs, and phytosaurs. Their size and position suggest a




Fig. 70. — Tooth of
Tylosaurus, two-thirds
natural size.



i54



WATER REPTILES OF THE PAST AND PRESENT



use like that of the modern aquatic monitors, as mentioned on a
preceding page. The eyes were of moderate size, those of the less
purely aquatic forms being directed more laterally than those of
species of more distinctly diving habits. They were protected
by a stout ring of bony plates, as were the eyes of all truly aquatic
reptiles of the past. The ears, also, in most if not all mosasaurs,
had a thick cartilaginous ear-drum in place of a simple membrane,
evidently, as Dollo has shown, for better protection under undue
pressure of the water in deep diving.

As in all other lizards, the bones with which the lower jaws
articulate, the quadrates, were loosely attached at the upper end,
permitting great freedom of movement in all directions, more even
than the land lizards have. The lower jaws were long and powerful,
armed with a- single row of teeth on each side, from sixteen to




Fig. 71. — Clidastes, inner side of right mandible: ang, angular; art, articular;
cor, coronoid; pa, prearticular; sur, surangular.

eighteen in number. Just back of the teeth, a little beyond the
middle, each mandible has a remarkable joint, quite unknown in
land lizards, though a trace of it is found in the monitors, per-
mitting much movement between the front and back parts, both
laterally and vertically, though chiefly in the former direction.
Furthermore, as in land snakes but not as in land lizards, the
front ends of the two sides of the jaws were somewhat loosely
attached to each other by ligaments. This looseness of the two
sides of the jaws, not only in front but also behind, together with
the joint in each, was of the greatest use in swallowing prey, as
will be explained farther on.

As in most other aquatic reptiles, the neck was short and strong,
the vertebrae being less in number than in most other lizards.
The trunk was long and slender, more especially so in the surface-
swimming kinds, with from twenty-two to thirty-four vertebrae.



SQUAMATA



155



The tail was long, no longer than the tail of some land lizards,
but more powerful, and broader and natter. It was expanded or




Fig. 72. — Skulls of mosasaurs. Upper figure, Clidastes, from the side; middle
figure, Platecarpus, from below; lower figure, Tylosaurus, from above: an, angular;
bs, basisphenoid; c, coronoid; ep, epipterygoid; fr, frontal; j, jugal; I, lacrimal; m,
maxilla; na, nasal; oc, occipital condyle; pa, parietal, palatine; pm, premaxilla;
pf, prefrontal; pt, pterygoid; po, postorbital; q, quadrate; sp, splenial; sq, squa-
mosal; Ir, transverse; v, vomer.

dilated more or less toward the free end, that is, with the beginning
of a terminal caudal fin, such as the more specialized ichthyosaurs
and crocodiles possessed. The vertebrae were procoelous, that is,



156 WATER REPTILES OF THE PAST AND PRESENT

concave in front and convex behind, like those of most modern
lizards and all modern snakes and crocodiles, but quite unlike the
biconcave vertebrae of all other aquatic reptiles. This kind of
articulation of the backbones gave greater firmness and strength
to the spinal column, but decreased the flexibility, and its posses-
sion by these animals was doubtless due to their descent from
land lizards which had already acquired it. The loss of flexibility,
however, was partly compensated by the loss of the additional
articulating surfaces of the tail.

As in all other aquatic reptiles, it is in the limbs that the most
striking characteristics of these water lizards or "sea-serpents"
are found. The legs were so completely adapted to an aquatic

mode of living that the ani-
mals must have been practi-
cally helpless upon land, able
perhaps to move about in a
serpentine way when acci-
dentally stranded upon the
beaches, but probably never
seeking the land voluntarily.
Fig. 73—Plaiecarpus; occipital view of The front limbs, like those of
skull: bo, basioccipital; eo, exoccipital; pf, ^ other sw i mm i ng animals
postfrontal; st, stapes; pt, pterygoid; q, . . , ,,.

quadrate. having a powerful propelling

tail, were larger than the
hind ones, though not very much so. The bones of the first
two segments, that is, the arm, forearm, and thigh and leg
bones, were all short and broad, resembling those of the ichthyo-
saurs more than those of any other reptiles, save perhaps the
thalattosaurs, discussed below. The articular surfaces of all the
the limb bones, as in other aquatic animals, were restricted in extent,
indicating limited motion between the joints, though doubtless
having great flexibility. In the most specialized types, such as
Tylosaurus, the wrist and ankle bones were almost wholly carti-
laginous, just as they are in the water salamanders, and in whales
and porpoises. This tendency of the ends of long bones, the wrists
and ankles as well as other bones of the skeleton, to become more
cartilaginous, or less well ossified, in animals purely aquatic in




SQUAMATA



157



habit is a marked one. So much is this the case that paleontolo-
gists always suspect water habits in reptiles showing it, even though
but few parts of the skeleton are known.

Increase in the number of bones of the digits is a more or less
conspicuous characteristic of all mosasaurs. In those forms in








Fig. 74. — Clidastes; left front paddle: Fig. 75. — Tylosaurus; left front paddle:

c, coracoid; h, humerus; r, radius; sc, c, coracoid; sc, scapula; h, humerus; r,
scapula; it, ulna. radius; u, ulna.



which the wrists and ankle bones had become cartilaginous in great
part, as many as eleven phalanges have been observed in the longest
toes, though in other forms, those with more completely ossified
wrists and ankles, only two or three additional bones have been
developed in the longest fingers and toes by aquatic habits. The



i58



WATER REPTILES OF THE PAST AND PRESENT



pliability and flexibility of the fingers and toes were certainly very
great, but they could .not possibly have been flexed or bent so
as to grasp or seize anything; and of course all vestiges of claws
had disappeared. Many specimens have been found with all the
bOnes of the limbs, that is, the "paddle bones," in the positions they

occupied when the animals
died. Figures of three such
specimens, made from photo-
graphs or careful drawings by
the writer, are shown here-
with (Figs. 74-76) . In several
such specimens very clear
impressions of the smooth
membranes between the
fingers have been observed,
and in one specimen pre-
served in the collections of
the University of Kansas the
outline of the fleshy parts
connecting the paddle with
the body has been preserved.
It will be seen by com-
parison of the figures of the
mosasaur paddles with those
of the ichthyosaurs and ple-
siosaurs that there was a wide
difference in their structure,
though all have the charac-
teristic shortening of the limb
bones and increase in the
numbers of the finger and
toebones, that is hyperphalangy. It is probable that these differ-
ences mean a more powerful and varied use of the limbs in the
mosasaurs. It is certain that the mosasaurs were much more pre-
daceous and pugnacious in their habits than were any other truly
aquatic backboned air-breathing animals of the past or present.
They were the "land sharks" of the ancient seas, and probably




Fig. 76. — Platecarpus; right front paddle :
h, humerus; r, radius; u, ulna.



SQUAMATA



159



the only ones among water reptiles that would be dangerous and
offensive to man, were they all living today.

For a long time it was thought that the mosasaurs had no
breast bone, and that, in consequence, the front part of the thorax
was expansible. Under this assumption the mosasaurs would have
been much more snake-like in habit than they really were. The
loose construction of the jaws doubtless permitted the swallowing
of prey of considerable size, and the inference was that they habitu-
ally preyed upon animals of large size. A snake will often swallow
a frog of larger diameter than its own body, the flexible jaws and
loosely connected ribs permitting it to pass to the abdominal
cavity. But the unyielding ring formed by the anterior ribs con-
nected with the breast bone in the mosasaurs, as in other lizards,
conclusively proves that large animals could not have been swal-




Fig. 77. — Platecarpus; pelvis, from below: p, pubis; il, ilium; is, ischium



lowed whole by the mosasaurs. In several instances the fossilized
stomach contents, composed chiefly or wholly of fishes, have been
found between the ribs of mosasaurs, and in none were the fishes
more than two or three feet in length, though the reptiles were
from sixteen to twenty feet long. Possibly the largest mosasaurs
those thirty or thirty-five feet in length, might have captured and
swallowed fishes six or seven feet long, but in all probability their
usual prey was of smaller relative size.

The very loose construction of the pelvic bones, those to which
the hind legs are articulated, is an evidence of more complete
adaptation to water life than was or is the case with any other
water air-breathers except the ichthyosaurs and cetaceans. The
sacrum had entirely lost its function as a support to the pelvis
and had disappeared, that is, the vertebrae composing it had become



160 WATER REPTILES OF THE PAST AND PRESENT

quite like the adjacent ones, by the loss of the ribs connecting them
with the ilium. The small pelvis was suspended loosely in the
walls of the abdomen, or at the most was feebly connected with
a single vertebra by ligaments. It was entirely useless as a support
for the legs. The mosasaurs could not possibly have raised their
bodies from the ground while on land. It is well known that the
land lizards and the crocodiles raise their bodies free from the ground
while running or walking; none drags its body over the surface.

In several instances complete or nearly complete skeletons of
mosasaurs have been discovered with the different bones nearly
all in the positions and relations they had after the decomposition
of the flesh, together with the carbonized remains of the skin and




Fig. 78. — Photograph of carbonized remains of scales of Tylosaurus, natural size

impressions of the investing scales and membranes. The nature
of the body covering is therefore known with certainty from nearly
all parts of the body. The body everywhere, save on the mem-
brane between the fingers and toes, and perhaps on the top of the
skull, was covered with small overlapping scales, very much like
those of the monitors. These scales, however, were small and
smooth in comparison with the size of the animals, those of a
mosasaur twenty feet in length being almost precisely the size
of those of a monitor six feet long. The top of the skull seems to
have been covered with horny plates, as in most lizards. In one
instance parallel dark bars, obliquely placed, and of narrow width,
formed by carbonized pigment, were observed by the writer. As
has been stated, in some instances fish bones and fish scales have



SQUAMATA 161

been observed among the fossilized stomach contents, and it is
quite certain that the food of these creatures must have been com-
posed chiefly of fishes, though of course it is not improbable that
other small vertebrates, birds, pterodactyls, the young of plesiosaurs,
and possibly small mammals, may occasionally have formed a
part of their diet. That the mosasaurs were very pugnacious
in life is conclusively proved by the many mutilations of their
bones that have been observed, mutilations received during life
and partly or wholly healed at the time of death. Bones of all
vertebrates are repaired after injury by the growth of more or less
spongy osseous material about the injured part, forming a sort
of natural splint. This material is more or less entirely removed
by absorption when it is no longer required for the support of the
broken ends. Many such injured bones of the mosasaurs have
been found; sometimes the bones of the hands and feet have grown
together, and not infrequently the vertebrae have been found
united by these osseous splints; occasionally even the skull itself,
especially the jaws, attest extensive ante-mortem injuries. In a
single instance the writer has observed the loss of a part of the tail,
where it probably had been bitten off. It may be mentioned, how-
ever, that the bones of the tail had no such "breaking points" in
the mosasaurs as have those of many land lizards, whereby a part
or all may be lost as a result of even a trivial injury, and then
regrown. Such a condition in an organ relied upon entirely for
propulsion would have been immediately fatal to the existence of
the mosasaurs. The large jaws and teeth are in themselves suffi-
cient evidence of the fiercely carnivorous propensities of the mosa-
saurs. The constant renewal of the sharply pointed teeth, thereby
preventing deterioration by use or accident, preserved, even in the
oldest animals, the effectiveness of the youthful structure.

We may now understand how the mosasaurs seized and swal-
lowed their prey. Living constantly in the water, away from all
firm objects, with small, short limbs quite incapable of holding
struggling prey, and the body not sufficiently serpentine to hold
it in its folds after the manner of snakes, the mosasaurs would have
found it difficult or impossible to swallow fishes of even moderate


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Online LibrarySamuel Wendell WillistonWater reptiles of the past and present → online text (page 12 of 19)