Samuel Wendell Williston.

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peculiar discovery he had made the present writer found several
specimens of plesiosaurs in the chalk of western Kansas with which
similar pebbles were associated, an account of which was given
soon afterward by the late Professor Mudge. Since then numerous
like discoveries have made it certain that the plesiosaurs usually, if
not always, swallowed such pebbles in considerable quantities, for
what purpose we do not yet feel sure; one can only hazard a guess.
The small size of the pebbles, or gastroliths, as they have been
called, a half -inch or less in diameter, found with skeletons of large
size, indicate much more complete digestion of the hard parts of
their food than is the case with many other reptiles; no solid sub-
stance of size could have passed out of the plesiosaur stomach, and
such is the case with the modern crocodiles, which have a like habit
of swallowing pebbles. That the plesiosaurs picked up these sili-
ceous pebbles, sometimes weighing a half-pound, accidentally with
their food is highly improbable; they surely had something to do
with their food habits. It is not at all unreasonable to suppose
that the plesiosaurs, because of their comparative sluggishness, fed
upon anything of an animal nature, whether living or dead, which
came in their way; that carrion, squids, crustaceans, and fishes
were all equally acceptable; they were probably largely scavengers
of the old oceans. Barnum Brown found among the stomach
contents of a plesiosaur fragments of fish and pterodactyl bones,
and cephalopod shells. Gallinaceous birds, most of which have the
same pebble-swallowing habit, have a thick-walled muscular stomach
or gizzard, in which the pebbles serve as an aid in the trituration
of food. Modern crocodiles, with the same pebble-swallowing
habit, have a thick-walled muscular stomach, gizzard-like, though
of course not as large as in birds; and the same habit has been
noted by Des Longchamps in the ancient teleosaur crocodiles.
It is hardly possible yet to decide whether or not the plesiosaurs
were denizens of the open oceans for the most part, far from land.



94 WATER REPTILES OF THE PAST AND PRESENT

That many of them were rovers is quite certain. With the skeleton
of a large plesiosaur found some years ago in western Kansas, there
were many siliceous pebbles which could have come only from the
shores of the old Cretaceous seas about the Black Hills, hundreds
of miles distant. Some of the pebbles are red quartzite, quite
identical with that of the bowlders brought to Kansas millions of
years later by the glacial drift from outcroppings near the northern
line of Iowa. The bones of plesiosaurs are often found in deposits
believed to be of deep-water origin. But they are also found in
Kansas associated with the remains of small turtles, flying reptiles,
and birds which could only have lived near the shores. Indeed,
their remains have often been found with those of strictly fresh-
water animals which had been brought down by the floods to the
seas. Their wide but rather sparse distribution in all kinds of
marine sediments would rather indicate that they were at home far
out in the tempestuous ocean or near the shores in protected bays,
though probably they preferred the shallow- water littoral regions.
One conclusion is quite justified: they were not gregarious, as were
the ichthyosaurs.

It is not certain that the plesiosaurs were viviparous, though
there are good reasons for the belief that they were. Remains of
two embryos were found years ago in England associated in such
a way that it is reasonable to suppose they were unhatched young,
though embryos have never yet been found associated with skele-
tons of adults, as have those of ichthyosaurs in numerous instances.
Bones of young, often quite young, plesiosaurs, are frequently
found in shallow-water deposits, and if the young were actually
born alive they must have swum freely in the open waters while
yet of very tender age. Rather singularly, however, the remains
of these young plesiosaurs always occur as isolated bones.

In geological range the plesiosaurs were very persistent, extend-
ing through nearly all the Mesozoic. They began their career as
fully evolved plesiosaurs, so far as we now know, near the close of
the Triassic period, and reached their culmination in the Upper
Cretaceous, but survived to the close of that period. In the begin-
ning of their career they were associated with the marine crocodiles
and the ichthyosaurs, but outlived them to find companions and
probably enemies in the huge and voracious mosasaurs of the later



SAUROPTERYGIA 95

Cretaceous times. At no time do they appear to have been especially
numerous, nor does it seem probable that they were ever a domi-
nant type of marine vertebrate life, though their remains occur
everywhere that marine deposits of the Jura and Cretaceous are
known. Indeed, it may be said with almost certainty that rocks of
these ages and of that character everywhere in the world contain
fossil plesiosaurs. Their bones have been made known from
Europe, Asia, Africa, Australia, and North and South America.
From North America thirty or more species have been described
from New Jersey, Alabama, Mississippi, Texas, Arkansas, Kansas,
Nebraska, Colorado, New Mexico, Wyoming, North and South
Dakota, California, etc.

The cause of their final extinction no one knows, nor can we
conjecture much about it with assurance. That climatic conditions
became unfavorable for them is highly improbable, considering
their cosmopolitan habits; they were not discriminating in their
environments. After successfully withstanding their fiercest foes,
the ichthyosaurs, crocodiles, and mosasaurs, and large carnivorous
fishes, it does not seem probable that they would succumb to lesser
enemies, though it may be that they were finally attacked success-
fully, not in the fulness of their strength as adults, but while young,
by more insidious enemies. More probably after their long life of
millions of years they had grown old, as everything grows old, and
had become so fixed and unplastic in their structure and habits
that even slight causes were at last their undoing. When we shall
have bridged over that still imperfectly known transition period
between the great Age of Reptiles and the greater Age of Mammals
we shall have learned more definitely some of the causes of the
extraordinary revolution in vertebrate life that then occurred.
The plesiosaurs went out with nearly all of their kind, the mosa-
saurs, the pterodactyls, the dinosaurs; and, so far as we now know,
their places in the sea, land, and air were not immediately taken
by any other creatures.

NOTHOSAURIA

A few years after the discovery of the plesiosaurs by Conybeare,
the remains of animals of allied kinds were found in the Triassic
rocks of Bavaria. At first they were supposed to be those of true



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WATER REPTILES OF THE PAST AND PRESENT





SAUROPTERYGIA 97

plesiosaurs, and even the astute Cuvier was not very clear about
them. Cuvier was the first to call attention to them, expressing
the opinion that some of the fossils were of previously unknown
animals allied to the crocodiles, lizards, and plesiosaurs. It was
von Meyer, however, who first introduced a nothosaur to the
scientific world under the name Conchiosaurus. A year later
Count George of Miinster described other forms under the name
Nothosaurus, meaning "false lizard." Count von Miinster was a
most zealous collector of the fossils of the Triassic deposits of
Bavaria, amassing, after thirty years of active and enthusiastic
labor, a very large amount of material, which, at his death, was
purchased by the King of Bavaria and placed in the hands of von
Meyer for study. Von Meyer was to Germany what Owen was to




Fig. 45. — Head and neck of Nothosaurus; photograph of specimen in the Sencken-
berg Museum, from Dr. Dreverman.

England, a man of deep learning, having an extensive knowledge
of comparative anatomy, and being thorough and critical in his
work. His descriptions and illustrations of these rich collections
made by von Miinster are masterpieces of scientific thoroughness.
He recognized in Nothosaurus and other allied forms from the
Bavarian Triassic a distinct group of semiaquatic reptiles allied to
the plesiosaurs, and his conclusions have never been gainsaid. In
more recent years additional remains of these animals from Bavaria
and other places in Europe have been described, but none are
known from other parts of the earth, or from other than Triassic
rocks. Altogether about ten genera and about twice as many
species have been described, probably all belonging in one family,
and all by common consent now classified with the Sauropterygia.



98



WATER REPTILES OF THE PAST AND PRESENT




Fig. 46. — Pectoral girdle of Nothosaurus, from
photograph by E. Fraas: id, interclavicle; d,
clavicle; sc, scapula; cor, coracoid.



The Nothosauria were much smaller reptiles than the plesio-
saurs, none of them perhaps exceeding the size of the smallest known
plesiosaurs. They were semiaquatic in habit, with many curious

resemblances to other
semiaquatic reptiles of
a later time known, as
the dolichosaurs. The
neck is more or less
elongated, having about
twenty vertebrae in the
longest-necked forms;
the body is moderately
long, and broad, and
the tail is relatively
short. The vertebrae
and ribs are quite like
those of the plesiosaurs,
that is, the vertebrae
are gently concave at
each end, and the dorsal ribs are attached by a single head to the
transverse process high up on the arch ; the cervical ribs are double-
headed, precisely like those of the older plesiosaurs, one of the char-
acters which insistently proves
the relationships of the two
groups. The bones of the shoul-
ders (Fig. 46) also have many
resemblances to the extraor-
dinary ones of the plesiosaurs,
though they are much less
specialized. There was no
sternum; the coracoids are
large, though very much
smaller than those of the plesi-
osaurs. The collar-bones are large and strong, joining each other
in front of the coracoids and firmly united with the shoulder-
blades at the outer extremity. Four vertebrae are united to form
a sacrum, and their union with the hip bones (Fig. 47) was much




Fig. 47. — Pelvic bones of Nothosaurus:
il, ilium; ac, acetabulum; p, pubis; is,
ischium. (After Andrews.)



SAURO PTERYGIA



99



firmer than was the case with the plesiosaurs. The limbs are
elongated, but it will be observed in the figures (Fig. 48) that the
radius and ulna, tibia and fibula, that is, the bones of the forearm
and of the leg proper, are relatively very short as compared with
the humerus and femur, a sure indication of the beginning of
aquatic habits. The toes and fingers were doubtless webbed, and
there was no increase in the num-
bers of bones in the digits, so
conspicuous in the plesiosaurs.
The external nostrils are large, but
are not situated so far back near
the eyes as in the plesiosaurs.
There is a large pineal opening in
the top of the skull, as in the plesi-
osaurs, but no sclerotic or bony
plates have been observed in the
eyes. They had ventral ribs like
those of the plesiosaurs.

No impressions of scales or
bony plates have ever been found
with the remains of the notho-
saurs, and it is the belief that the
skin was bare. A good idea of
their general appearance will be
gained from the accompanying
restoration adapted from that of
Professor Fraas (Fig. 44) and the
restoration of the less highly
specialized Lariosaurus , made
from a very complete skeleton in
the Frankfort museum (Fig. 49).

It has been thought that these nothosaurs, so intermediate in
structure between the true plesiosaurs and land reptiles, were the
actual ancestors, but this is rather doubtful. It is probable that
they were only very closely akin to the real ancestors, since in some
ways they had become specialized too much, and, as we have
already explained, highly specialized characters or organs can never




fii\\!\m



1









Fig. 48. — Legs of Lariosaurus bal-
sami, an Upper Triassic nothosaur: h,
humerus; r, radius; u, ulna; i, inter-
medium; ue, ulnare; /, femur; fi,
fibula; t, tibia; a, astragalus; c, cal-
caneum. (After Abel.)



ioo WATER REPTILES OF THE PAST AND PRESENT




Fig. 49. — Lariosanrus balsami



SAUROPTERYGIA 101

go back to their earlier condition. The nothosaurs do prove
beyond all possibility of doubt that the plesiosaurs were at least
the descendants of animals closely allied to them, so closely, indeed,
that it is doubtful whether we could distinguish external differences
were all of them actually living at the present time.

We have repeatedly seen that all aquatic animals have some
or all the bones of the limbs shortened, and it is of interest to
observe that the early plesiosaurs had longer forearm and foreleg
bones than the later ones, just as we have seen was the case with the
early ichthyosaurs. It would seem probable that all the early
plesiosaurs had long necks, though some of the late ones in Cre-
taceous times had relatively short necks, shorter even than the
known nothosaurs possessed.

The nothosaurs doubtless lived about the shores of the ancient
seas, spending much of their time in the water, leaving it perhaps
when hard pressed by their enemies, as do some modern reptiles,
or to rear their young. The teeth of the nothosaurs are long
and slender in front, shorter behind. The animals must therefore
have been carnivorous in habit, feeding probably upon such fishes
as they could catch, and the various invertebrates which live in
shallow water. The structure of the jaws and their attachments
are quite as in the plesiosaurs, proving that they could not have
swallowed large objects; but the skull is broader and flatter than
that of most plesiosaurs, indicating habits not unlike those of the
modern alligators and crocodiles.

Some time we shall doubtless find remains of nothosaurs or
nearly allied animals elsewhere than in Europe, but probably not
from later deposits than the Triassic. So far as we now know, their
geological range and geographical distribution were much restricted;
they evidently wholly died out shortly after the plesiosaurs appeared



CHAPTER VII

ANOMODONTIA
LYSTROSAURUS

Over a large area of South Africa, chiefly along the Orange
River and its tributaries, there is an extensive series of deposits
many hundreds of feet in thickness, usually called the Karoo beds,
which, for more than fifty years, have been widely famous among
scientific men for the many and remarkable vertebrate fossils
which they have yielded. These deposits seem to represent the
whole of the vast interval of time from the Carboniferous to the
Jurassic, that is, the whole of the Permian and Triassic, though
not many fossils have been found in the lowermost strata. Among
the fossils of the lower strata are those of the strange creatures
described in the following pages as Mesosaurus. From the deposits
representing the Upper Permian and the Triassic the fossils that
have been obtained are both abundant and diverse. Unfortu-
nately, however, of the scores of forms that have been discovered
few are known completely, and still fewer are known sufficiently
well to enable us to picture the living animals.

From the Upper Permian Karoo rocks two orders of reptiles
have been recognized, the Cotylosauria, represented by more
specialized forms than those from the Lower Permian of North
America; and the order or group called by Broom the Therapsida.
While the forms of this latter group have certain definite structural
relationships with each other, they show so great a diversity among
themselves that, when they shall be better known, it will be
found necessary perhaps to separate them into several distinct
orders.

At least five groups of the Therapsida are now recognized by
Broom, the Dromasauria, Dinocephalia, Anomodontia, Thero-
cephalia, and Theriodontia. Of all these the members of the
last-mentioned group have attracted the greatest interest among



ANOMODONTIA 103

geologists and naturalists, because of their intimate relationships to
the mammals — so intimate, indeed, that they seem almost to bridge
over the interval between the two classes. From higher Karoo
beds primitive representatives of the more crocodilian types have
been discovered, forms which seem to be the beginning of that
order described on later pages as the Parasuchia.

It would lead us too far astray to mention even, let alone
describe, the many forms of reptiles that have been discovered
in the Karoo beds; nor indeed is it possible for anyone who
has not attentively studied their remains to get a very clear con-
ception of many of them, so incompletely have they been made
known.

Doubtless from among all these diverse forms there have been
not a few which sought wider opportunities in the water, but, if so,
we have as yet very little knowledge of them. One form only, so far
as the writer is aware, has been credited with aquatic habits, a
remarkable reptile belonging to the group originally called by
Sir Richard Owen, the Anomodontia, a word meaning "lawless
teeth," and to the genus Lystrosaurus, also described by the same
noted paleontologist. A restoration of the skeleton of Lystro-
saurus has recently been published by Watson. This restoration
the writer has reproduced in the present pages, though he has
taken the liberty of making some minor changes, to accord better
with what he believes must have been the position of the shoulder-
blades and the hind legs. And he would also suggest that the tail
in life did not turn down so much at its extremity as depicted by
Watson.

Both Broom and Watson believe that this animal was a power-
ful swimmer, and thoroughly aquatic in habit. To the present
writer, however, this does not seem so evident. He is rather
inclined to believe that the creature was chiefly terrestrial in habit,
living probably in marshy regions, and perhaps seeking its food
in shallow waters and in the mud. Aside from the position of the
nostrils, which it will be observed are rather close to the eyes,
a position so characteristic of many swimming reptiles and mam-
mals, there is but little indication of aquatic adaptations elsewhere
in the skeleton.



104 WATER REPTILES OF THE PAST AND PRESENT

r-O




ANOMODONTIA 105

The skull is of most extraordinary form. The face is turned
downward, leaving the nostrils high up, in front of the eyes. The
jaws were doubtless covered with a horny shield, like that of the
turtles, having a cutting edge. There is a single pair of elongated
canine teeth, possibly a sexual character. The lower jaws are
heavy and stout, and Watson has said that the animal doubtless
had the ability to open its mouth very widely. The quadrate, the
bone with which the lower jaws articulate, is firmly fixed to the
skull, and there is a single opening on the side of the skull poste-
riorly, a character common to all the Therapsida.

The vertebrae are stout, and they have stout spines. The tail
is remarkably short, stout, and stumpy; it could have been of no
use whatever in the water for propulsion or even for steering. The
front legs are short and stout; the forearm bones are short, sug-
gesting either swimming or digging habits, and the foot is short and
broad. The pelvis or hip bones are massive and were very firmly
connected with the backbone by the aid of six vertebrae, a very
unusual number in reptiles. The hind legs, as figured, show no
indications whatever of aquatic adaptation, unless possibly the
very slight shortening of the shin may be so construed. Watson
believes that the bones of the pelvis, indicate, aside from its strong
union with the backbones, strong swimming powers, but of this
again the present writer is very skeptical. The very strong ischia
and the flatness of the pelvis are both characters found among
American Permian reptiles, which do not show otherwise the
slightest indications of water habits.

If then Lystrosaurus was a powerful swimmer, as has been
maintained, it is very evident that the hind legs must have been
used as the seals or sea-otters use them, to propel and to guide;
but they in nowise resemble the legs of these swimming mammals.
It seems altogether more reasonable to suppose that Lystrosaurus
lived in the marshes, feeding upon vegetable food obtained by aid
of its strong jaws and tusks — if the tusks were possessed by both
sexes; and that the position of the nostrils may be ascribed to
causes like those which brought about their recession in the Phyto-
sauria, and not to strictly aquatic habits. Possibly the animal had
habits somewhat similar to those of the hippopotamus; that it was



106 WATER REPTILES OF THE PAST AND PRESENT

an expert swimmer appears, to the present writer, improbable.
The powerful front legs may be indicative of digging habits; the
animal may have used them as an aid to its powerful jaws and
tusks in uprooting marsh and water plants. However, Lystro-
saurus, whatever may have been its habits, was a curious reptile.
It was about three feet in length, massive in all its structure, and
doubtless of slow and sluggish gait.



CHAPTER VIII

ICHTHYOSAURIA

Early in the eighteenth century a curious work in the Latin
language was published by a famous physician and naturalist — a
professor in the University of Altorf by the name of Scheuchzer —
entitled Querulae Piscium, or "Complaints of the Fishes." The
work was illustrated by many expensively engraved figures of vari-
ous fossil remains, including one of some vertebrae which the
author referred to as "the accursed race destroyed by the flood"!
The history of the finding of these famous bones is recorded by
Cuvier as follows:

Scheuchzer, while walking one day with his friend Langhans in the vicinity
of Altorf, a village and university of Nuremburg, went to the vicinity of the
gallows to make some researches. Langhans, who had entered the inclosure
of the gallows, found a piece of limestone containing eight dorsal vertebrae,
of a black color and shining. Seized, says Scheuchzer, with a panic terror,
Langhans threw the fragment of limestone beyond the wall of the inclosure,
and Scheuchzer, picking it up, preserved two of the vertebrae which he believed
to be human, and which he figured in his book, Piscium Querulae.

About the same time another observer by the name of Baier
discovered other and similar vertebrae in the vicinity of Altorf
which he described and figured as those of a fish; and there was
much earnest contention between Scheuchzer and Baier, as also
between their friends, as to their supposed nature. Scheuchzer's
figure was often cited as indubitable evidence of the destruction of
mankind by a universal flood, and it was not until nearly a century
later that Cuvier showed that the bones were really those of a
marine reptile.

It must be recollected, in extenuation of so extraordinary a
blunder on the part of so learned a man as was Scheuchzer, who,
as a physician and professor, one would think ought to have been
able to distinguish between vertebrae so different as are those of an
ichthyosaur and a man, that, during all of the eighteenth century

107



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WATER REPTILES OF THE PAST AND PRESENT



and well into the nineteenth, the belief was prevalent that all
fossils were the relics of animals and plants that had perished in




Fig. 51. — Restoration of Ichthyosaurus with young, by Charles R. Knight. (By
permission of the American Museum of Natural History.)

the great biblical flood. The science of geology was yet in its
infancy, and there was no known record, other than the biblical
one, of any great inundation of the earth's surface which might



ICHTHYOSA URIA 109 .

account for the remains of sea-animals in rocks remote from the
seas. This belief, so long held by even the wisest and most learned
of scholars, so long welcomed by the theologians as proof of the
literal accurracy of the Bible, was one of which Scheuchzer was
quite convinced. His Piscium Querulae was largely a fantastic
discussion of the supposed great world-catastrophe, the Noachian
Deluge, by which the fishes had been destroyed and long imprisoned
in the rocks through no sin of their own.

It was the same author who, in a subsequent work, described and
figured the fossil skeleton of a large salamander which he believed
to be that of a child destroyed in the flood, and which he called
"Homo diluvii testis." In this specimen, which was discovered in
the Tertiary rocks of Oeningen, and which is still preserved among


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Online LibrarySamuel Wendell WillistonWater reptiles of the past and present → online text (page 8 of 19)