DISCOVERY OF THE PTERODACTYLE
Late in the eighteenth century, in 1784, a small fossil animal with
wings began to be known through the writings of Collini, as found in the
white lithographic limestone of Solenhofen in Bavaria, and was regarded
by him as a former inhabitant of the sea. The foremost naturalist of the
time, the citizen Cuvier--for it was in the days of the French
Republic--in 1801, in lucid language, interpreted the animal as a genus
of Saurians. That word, so familiar at the present day, was used in the
first half of the century to include Lizards and Crocodiles; and
described animals akin to reptiles which were manifestly related neither
to Serpents nor Turtles. But the term saurian is no longer in favour,
and has faded from science, and is interesting only in ancient history
of progress. The lizards soon became classed in close alliance with
snakes. And the crocodiles, with the Hatteria, were united with
chelonians. Most modern naturalists who use the term saurian still make
it an equivalent of lizard, or an animal of the lizard kind.
CUVIER
[Illustration: FIG. 11. _PTERODACTYLUS LONGIROSTRIS_ (Cuvier)
The remains are preserved with the neck arched over the back, and the
jaws opened upward]
Cuvier defined this fossil from Solenhofen as distinguished by the
extreme elongation of the fourth digit of the hand, and from that
character invented for the animal the name Pterodactyle. He tells us
that its flight was not due to prolongation of the ribs, as among the
living lizards named Dragons; or to a wing formed without the digits
being distinguishable from each other, as among Birds; nor with only one
digit free from the wing, as among Bats; but by having the wing
supported mainly by a single greatly elongated digit, while all the
others are short and terminate in claws. Cuvier described the amazing
animal in detail, part by part; and such has been the influence of his
clear words and fame as a great anatomist that nearly every writer in
after-years, in French and in English, repeated Cuvier's conclusion,
maintained to the end, that the animal is a saurian.
[Illustration: FIG. 12. THE SKELETON OF _PTERODACTYLUS LONGIROSTRIS_
Reconstructed from the scattered bones in Fig. 14, showing the limbs
on the left side]
Long before fashion determined, as an article of educated belief, that
fossil animals exist chiefly to bridge over the gaps between those which
still survive, the scientific men of Germany were inclined to see in the
Pterodactyle such an intermediate type of life. At first Soemmerring and
Wagler would have placed the Pterodactyle between mammals and birds.
GOLDFUSS
[Illustration: FIG. 13. THE _PTERODACTYLUS LONGIROSTRIS_ RESTORED
FROM THE REMAINS IN FIG. 11
Showing positions of the wing membranes with the animal at rest]
But the accomplished naturalist Goldfuss, who described another fine
skeleton of a Pterodactyle in 1831, saw in this flying animal an
indication of the course taken by Nature in changing the reptilian
organisation to that of birds and mammals. It is the first flash of
light on a dark problem, and its brilliance of inference has never been
equalled. Its effects were seen when Prince Charles Bonaparte, the
eminent ornithologist, in Italy, suggested for the group the name
Ornithosauria; when the profound anatomist de Blainville, in France,
placed the short-tailed animal in a class between Reptiles and Birds
named Pterodactylia; and Andreas Wagner, of Munich, who had more
Pterodactyles to judge from than his predecessors, saw in the fossil
animal a saurian in transition to a bird.
VON MEYER
But the German interpretation is not uniform, and Hermann von Meyer, the
banker-naturalist of Frankfurt a./M., who made himself conversant with
all that his predecessors knew, and enlarged knowledge of the
Pterodactyles on the most critical facts of structure, continued to
regard them as true reptiles, but flying reptiles. Such is the influence
of von Meyer that all parts of the world have shown a disposition to
reflect his opinions, especially as they practically coincide with the
earlier teaching of Cuvier. Owen and Huxley in England, Cope and Marsh
in America, Gaudry in France, and Zittel in Germany have all placed the
Pterodactyles as flying reptiles. Their judgment is emphatic. But there
is weight of competent opinion to endorse the evolutionary teaching of
Goldfuss that they rise above reptiles. To form an independent opinion
the modern student must examine the animals, weigh their characters bone
by bone, familiarise himself, if possible, with some of the rocks in
which they are found; to comprehend the conditions under which the
fossils are preserved, which have added not a little to the interest in
Pterodactyles, and to the difficulty of interpretation.
GEOLOGICAL HISTORY OF PTERODACTYLES IN GERMANY
We may briefly recapitulate the geological history. Those remains of
Ornithosaurs which have been mentioned, with a multitude of others which
are the glory of the museums of Munich, Stuttgart, Tuebingen,
Heidelberg, Bonn, Haarlem, and London, have all been found in working
the lithographic stone of Bavaria. The whitish yellow limestone forms
low, flat-topped hills, now isolated from each other by natural
denudation, which has removed the intervening rock. The stone is found
at some distance north of the Danube, in a line due north of Augsburg,
in the country about Pappenheim, and especially at the villages of
Solenhofen, Eichstaedt, Kelheim, and Nusplingen. These beds belong to the
rocks which are named White Jura limestone in Germany, which is of about
the same geological age as the Kimeridge clay in England. Much of it
divides into very thin layers, and in these planes of separation the
fossils are found. They include the _Ammonites lithographicus_ and a
multitude of marine shells, king crabs and other Crustacea, sea-urchins,
and other fossils, showing that the deposit was formed in the sea. The
preservation of jelly-fish, which so soon disappear when left dry on the
beach, shows that the ancient calcareous mud had unusual power of
preserving fossils. Into this sea, with its fishes great and small, came
land plants from off the land, dragonflies and other insects, tortoises
and lizards, Pterodactyles with their flying organs, and birds still
clothed with feathers. Sometimes the wing membranes of the flying
reptiles are found fully stretched by the wing finger, as in examples to
be seen at Munich and in the Yale Museum in Newhaven, in America. At
Haarlem there is an example in which the wing membrane appears to be
folded much as in the wing of a Bat, when the animal hangs suspended,
with the flying membrane bent into a few wide undulations.
The Solenhofen Slate belongs to about the middle period of the history
of flying reptiles, for they range through the Secondary epochs of
geological time. Remains are recorded in Germany from the Keuper beds at
the top of the Trias, which is the bottom division of the Secondary
strata; and I believe I have seen fragments of their bones from the
somewhat older Muschelkalk of Germany.
THEIR HISTORY IN ENGLAND
In England the remains are found for the first time in the Lower Lias of
Lyme Regis, in Dorset, and the Upper Lias of Whitby, in Yorkshire. In
Wuertemberg they occur on the same horizons. They reappear in England, in
every subsequent age, when the conditions of the strata and their
fossils give evidence of near proximity to land. In the Stonesfield
Slate of Stonesfield, in Oxfordshire, the bones are found isolated, but
indicate animals of some size, though not so large as the rare bones of
reputed true birds which appear to have left their remains in the same
deposit.
At least two Pterodactyles are found in the Oxford clay, known from more
or less fragmentary remains or isolated bones; just as they occur in the
Kimeridge Clay, Purbeck Limestone, Wealden sandstones, and especially in
newer Secondary rocks, named Gault, Upper Greensand, and Chalk, in the
south-east of England.
Owing to exceptional facilities for collecting, in consequence of the
Cambridge Greensand being excavated for the valuable mineral phosphate
of lime it contains, more than a thousand bones are preserved, more or
less broken and battered, in the Woodwardian Museum of the University
of Cambridge alone. To give some idea of their abundance, it may be
stated that they were mostly gathered during two or three years, as a
matter of business, by an intelligent foreman of washers of the nodules
of phosphate of lime, which, in commerce, are named coprolites. He soon
learned to distinguish Pterodactyle bones from other fossils by their
texture, and learned the anatomical names of bones from specimens in the
University Museum. This workman, Mr. Pond, employed by Mr. William
Farren, brought together not only the best of the remains at Cambridge,
but most of those in the museums at York and in London, and the
thousands of less perfect specimens in public and private collections
which passed through the present writer's hands in endeavours to secure
for the University useful illustrations of the animal's structure. These
fragments, among which there are few entire bones, are valuable, for
they have afforded opportunities of examining the articular ends of
bones in every aspect, which is not possible when similar organic
remains are embedded in rock in their natural connexions.
In England Flying Reptiles disappear with the Chalk. In that period they
were widely distributed, being found in Bohemia, in Brazil, and Kansas
in the United States, as well as in Kent and other parts of England.
They attained their largest dimensions in this period of geological
time. One imperfect fragment of a bone from the Laramie rocks of Canada
was described, I believe, by Cope, though not identified by him as
Ornithosaurian, and is probably newer than other remains.
ASPECT OF PTERODACTYLES
If this series of animals could all be brought together they would vary
greatly in aspect and stature, as well as in structure. Some have the
head enormously long, in others it is large and deep, characters which
are shared by extinct reptiles which do not fly, and to which some birds
may approximate; while in a few the head is small and compact, no more
conspicuous, relatively, than the head of a Sparrow. The neck may be
slender like that of a Heron, or strong like that of an Eagle; the back
is always short, and the tail may be inconspicuous, or as long as the
back and neck together. These flying reptiles frequently have the
proportions of the limbs similar to those of a Bat, with fore legs
strong and hind legs relatively small; while in some the limbs are as
long, proportionately, and graceful as those of a Deer. With these
differences in proportions of the body are associated great differences
in the relative length of the wing and spread of the wing membranes.
DIMENSIONS OF THE ANIMALS
The dimensions of the animals have probably varied in all periods of
geological time. The smallest, in the Lithographic Slate, are smaller
than Sparrows, while associated with them are others in which the
drumstick bone of the leg is eight inches long. In the Cambridge
Greensand and Chalk imperfect specimens occur, showing that the upper
arm bones are larger than those of an Ox. The shaft is one and a half
inches in diameter and the ends three inches wide. Such remains may
indicate Pterodactyles not inferior in size to the extinct Moas of New
Zealand, but with immensely larger heads, animals far larger than birds
of flight.
The late Sir Richard Owen, on first seeing these fragmentary remains,
said "the flying reptile with outstretched pinions must have appeared
like the soaring Roc of Arabian romance, but with the features of
leathern wings with crooked claws superinduced, and gaping mouth with
threatening teeth." Eventually we shall obtain more exact ideas of their
aspect, when the structures of the several regions of the body have been
examined. The great dimensions of the stretch of wing, often computed at
twenty feet in the larger examples, might lead to expectations of great
weight of body, if it were not known that an albatross, with wings
spreading eleven feet, only weighs about seventeen pounds.