ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS
RHAMPHOCEPHALUS
THE Stonesfield Slate in England, which corresponds in age with the
lower part of the Great or Bath Oolite, yields many evidences of
terrestrial life--land plants, insects, and mammals--preserved in a
marine deposit. A number of isolated bones have been found of
Pterodactyles, some of them indicating animals of considerable size and
strength. The nature of the limestone was unfavourable to the
preservation of soft wing membranes, or even to the bones remaining in
natural association. Very little is known of the head of
Rhamphocephalus. One imperfect specimen shows a long temporal region
which is wide, and a very narrow interspace between the orbits; with a
long face, indicated by the extension of narrow nasal bones. The lower
jaw has an edentulous beak or spear in front, which is compressed from
side to side in the manner of the Liassic forms, but turned upward
slightly, as in Dorygnathus or Campylognathus. Behind this extremity are
sharp, tall teeth, few in number, which somewhat diminish in size as
they extend backward, and do not suddenly change to smaller series, as
in the Lias genera. A few small vertebrae have been found, indicating the
neck and back. The sacrum consists of five vertebrae. One small example
has a length of only an inch. It is a little narrower behind than in
front, and would be consistent with the animal having had a long tail,
which I believe to have been present, although I have not seen any
caudal vertebrae. The early ribs are like the early ribs of a Crocodile
or Bird in the well-marked double articulation. The later ribs appear to
have but one head. #V#-shaped abdominal ribs are preserved. Much of the
animal is unknown. The coracoid seems to have been directed forward,
and, as in a bird, it is 2-1/2 inches long. The humerus is 3-1/2 inches
long, and the fore-arm measured 6 inches, so that it was relatively
longer than in Dimorphodon. The metacarpus is 1-3/4 inches long. The
wing finger was exceptionally long and strong. Professor Huxley gave its
length at 29 inches. My own studies lead to the conclusion that the
first finger bone of the wing was the shorter, and that although they
did not differ greatly in length, the second was probably the longest,
as in Campylognathus.
Professor Huxley makes the second and third phalanges 7-3/4 inches long,
and the first only about 3/8 inch shorter, while the fourth phalange is
6-1/2 inches. These measurements are based upon some specimens in the
Oxford University Museum. There is only one first phalange which has a
length of 7-3/4 inches. The others are between 5 and 6 inches, or but
little exceed 4 inches; so that as all the fourth phalanges which are
known have a length of 6-1/2 inches, it is possible that the normal
length of the first phalange in the larger species was 5-1/2 inches. The
largest of the phalanges which may be classed as second or third is
8-1/2 inches, and that, I suppose, may have been associated with the
7-3/4 inches first phalange. But the other bones which could have had
this position all measure 5-1/2 and 7-3/4 inches. The three species
indicated by finger bones may have had the measurements:--
Phalanges of the wing finger
________________/\________________
| |
I. II. III. IV.
7-3/4 8-1/2 [7?] 6-1/2 } length of each bone
5-1/2 7-3/4 5-1/2 [4-1/2?] } in inches.
4-1/2 ---- ---- ---- }
The femur is represented by many examples--one 3-3/4 inches long, and
others less than 3 inches long (2-9/10). In Campylognathus, which has so
much in common with the jaw and the wing bones in size, the upper leg
bone is 2-8/10 inches. Therefore if we assign the larger femur to the
larger wing, the femur will be relatively longer in all species of
Rhamphocephalus than in Campylognathus. Only one example of a tibia is
preserved. It is 3-1/2 inches long, or only 1/10 inch shorter than the
bone in Campylognathus, which has the femur 2-8/10 inches, so that I
refer the tibia of Rhamphocephalus to the species which has the
intermediate length of wing. These coincidences with Campylognathus
establish a close affinity, and may raise the question whether the Upper
Lias species may not be included in the Stonesfield Slate genus
Rhamphocephalus.
The late Professor Phillips, in his _Geology of Oxford_, attempted a
restoration of the Stonesfield Ornithosaur, and produced a picturesque
effect (p. 164); but no restoration is possible without such attention
to the proportions of the bones as we have indicated.
OXFORD CLAY
A few bones of flying reptiles have been found in the Lower Oxford Clay
near Peterborough, and others in the Upper Oxford Clay at St. Ives, in
Huntingdonshire. A single tail vertebra from the Middle Oxford Clay,
near Oxford, long since came under my own notice, and shows that these
animals belong to a long-tailed type like Campylognathus. The cervical
vertebrae are remarkable for being scarcely longer than the dorsal
vertebrae; and the dorsal are at least half as long again as is usual,
having rather the proportion of bones in the back of a crocodile.
LITHOGRAPHIC SLATE
Long-tailed Pterodactyles are beautifully preserved in the Lithographic
Limestone of the south of Bavaria, at Solenhofen, and the quarries in
its neighbourhood, often with the skeleton or a large part of it
flattened out in the plane of bedding of the rock. Fine skeletons are
preserved in the superb museum at Munich, at Heidelberg, Bonn, Haarlem,
and London, and are all referred to the genus Rhamphorhynchus or to
Scaphognathus. It is a type with powerfully developed wings and a long,
stiff tail, very similar to that of Dimorphodon, so that some
naturalists refer both to the same family. There is some resemblance.
The type which is most like Dimorphodon is the celebrated fossil at
Bonn, sometimes called _Pterodactylus crassirostris_, which in a
restored form, with a short tail, has been reproduced in many
text-books. No tail is preserved in the slab, and I ventured to give the
animal a tail for the first time in a restoration (p. 163) published by
the _Illustrated London News_ in 1875, which accompanied a report of a
Royal Institution lecture. Afterwards, in 1882, Professor Zittel, of
Munich, published the same conclusion. The reason for restoring the tail
was that the animal had the head constructed in the same way as
Pterodactyles with a long tail, and showed differences from types in
which the tail is short; and there is no known short-tailed
Pterodactyle, with wrist and hand bones, such as characterise this
animal. The side of the face has a general resemblance to the
Pterodactyles from the Lias, for although the framework is firmer, the
four apertures in the head are similarly placed. The nostril is rather
small and elongated, and ascends over the larger antorbital vacuity. The
orbit for the eye is the largest opening in the head, so that these
three apertures successively increase in size, and are followed by the
vertically elongated post-orbital vacuity. The teeth are widely spaced
apart, and those in the skull extend some distance backward to the end
of the maxillary bone. There are few teeth in the lower jaw, and they
correspond to the large anterior teeth of Dimorphodon, there being no
teeth behind the nasal opening. The lower jaw is straight, and the
extremities of the jaws met when the mouth was closed. The breast bone
does not show the keel which is so remarkable in Rhamphorhynchus, which
may be attributed to its under side being exposed, so as to exhibit the
pneumatic foramina.
The ribs have double heads, more like those of a Crocodile in the region
of the back than is the case with the bird-like ribs from Stonesfield.
The second joint in the wing finger may be longer than the first--a
character which would tend to the association of this Pterodactyle with
species from the Lias; a relation to which attention was first drawn by
Mr. E. T. Newton, who described the Whitby skull.
The Pterodactyles from the Solenhofen Slate which possess long tails
have a series of characters which show affinity with the other
long-tailed types. The jaws are much more slender. The orbit of the eye
in Rhamphorhynchus is enormously large, and placed vertically above the
articulation for the lower jaw. Immediately in front of the eye are two
small and elongated openings, the hinder of which, known as the
antorbital vacuity, is often slightly smaller than the nostril, which is
placed in the middle length of the head, or a little further back,
giving a long dagger-shaped jaw, which terminates in a toothless spear.
The lower jaw has a corresponding sharp extremity. The teeth are
directed forward in a way that is quite exceptional. Notwithstanding the
massiveness and elongation of the neck vertebrae, which are nearly twice
as long as those of the back, the neck is sometimes only about half the
length of the skull.
All these long-tailed species from the Lithographic Stone agree in
having the sternum broad, with a long strong keel, extending far
forward. The coracoid bones extend outward like those of a Crocodile, so
as to widen the chest cavity instead of being carried forward as the
bones are in Birds. These bones in this animal were attached to the
anterior extremity of the sternum, so that the keel extended in advance
of the articulation as in other Pterodactyles. The breadth of the
sternum shows that, as in Mammals, the fore part of the body must have
been fully twice the width of the region of the hip-girdle, where the
slenderer hind limbs were attached. The length of the fore limb was
enormous, for although the head suggests an immense length relatively
to the body, nearly equal to neck and back together, the head is not
more than a third of the length of the wing bones. The wing bones are
remarkable for the short powerful humerus with an expanded radial crest,
which is fully equal in width to half the length of the bone. Another
character is the extreme shortness of the metacarpus, usually associated
with immense strength of the wing metacarpal bone.
The hind limbs are relatively small and relatively short. The femur is
usually shorter than the humerus, and the tibia is much shorter than the
ulna. The bones of the instep, instead of being held together firmly as
in the Lias genera, diverge from each other, widening out, though it
often happens that four of the five metatarsals differ but little in
length. The fifth digit is always shorter.
The hip-girdle of bones differs chiefly from other types in the way in
which those bones, which have sometimes been likened to the marsupial
bones, are conditioned. They may be a pair of triangular bones which
meet in the middle line, so that there is an outer angle like the arm of
a capital Y. Sometimes these triangular bones are blended into a curved,
bow-shaped arch, which in several specimens appears to extend forward
from near the place of articulation of the femur. This is seen in fossil
skeletons at Heidelberg and Munich. It is possible that this position is
an accident of preservation, and that the prepubic bones are really
attached to the lower border of the pubic bones.
Immense as the length of the tail appears to be, exceeding the skull and
remainder of the vertebral column, it falls far short of the combined
length of the phalanges of the wing finger. The power of flight was
manifestly greater in Rhamphorhynchus than in other members of the
group, and all the modifications of the skeleton tend towards adaptation
of the animals for flying. The most remarkable modification of structure
at the extremity of the tail was made known by Professor Marsh in a
vertical, leaf-like expansion in this genus, which had not previously
been observed (p. 161). The vertebrae go on steadily diminishing in
length in the usual way, and then the ossified structures which bordered
the tail bones and run parallel with the vertebrae in all the
Rhamphorhynchus family, suddenly diverge downward and upward at right
angles to the vertebrae, forming a vertical crest above and a
corresponding keel below; and between these structures, which are
identified with the neural spines and chevron bones of ordinary
vertebrae, the membrane extends, giving the extremity of the tail a
rudder-like feature, which, from knowledge of the construction of the
tail of a child's kite, may well be thought to have had influence in
directing and steadying the animal's movements. There are many minor
features in the shoulder-girdle, which show that the coracoid, for
example, was becoming unlike that bone in the Lias, though it still
continues to have a bony union with the elongated shoulder-blade of the
back.
[Illustration: FIG. 56. RESTORATION OF THE SKELETON OF
_RHAMPHORHYNCHUS PHYLLURUS_
From the Solenhofen Slate, partly based upon the skeleton
with the wing membranes preserved]
[Illustration: FIG. 57. RESTORATION OF THE SKELETON OF _SCAPHOGNATHUS
CRASSIROSTRIS_
Published in the _Illustrated London News_ in 1875. In which a tail is
shown on the evidence of the structure of the head and hand]
[Illustration: FIG. 58. SIX RESTORATIONS
1. Ramphocephalus. Stonesfield Slate. John Phillips, 1871
2. Rhamphorhynchus. O. C. Marsh, 1882
3. Rhamphorhynchus. V. Zittel, 1882
4. Ornithostoma. Williston, 1897
5. Dimorphodon. Buckland, 1836. Tail then unknown
6. Ornithocheirus. H. G. Seeley, 1865]
The great German delineator of these animals, Von Meyer, admitted six
different species. Mr. Newton and Mr. Lydekker diminish the number to
four. It is not easy to determine these differences, or to say how far
the differences observed in the bones characterise species or genera. It
is certain that there is one remarkable difference from other and older
Pterodactyles, in that the last or fourth bone in the wing finger is
usually slightly longer than the third bone, which precedes it. There is
a certain variability in the specimens which makes discussion of their
characters difficult, and has led to some forms being regarded as
varieties, while others, of which less material is available, are
classed as species. I am disposed to say that some of the confusion may
have resulted from specimens being wrongly named. Thus, there is a
Rhamphorhynchus called curtimanus, or the form with the short hand. It
is represented by two types. One of these appears to have the humerus
short, the ulna and radius long, and the finger bones long; the other
has the humerus longer, the ulna much shorter, and the finger bones
shorter. They are clearly different species, but the second variety
agrees in almost every detail with a species named hirundinaceus, the
swallow-like Rhamphorhynchus. This identification shows, not that the
latter is a bad species, but that curtimanus is a distinct species which
had sometimes been confounded with the other. While most of these
specimens show a small but steady decrease in the length of the several
wing finger bones, the species called Gemmingi has the first three bones
absolutely equal and shorter than in the species curtimanus, longimanus,
or hirundinaceus. In the same way, on the evidence of facts, I find
myself unable to join in discarding Professor Marsh's species phyllurus,
on account of the different proportions of its limb bones. The humerus,
metacarpus, and third phalange of the wing finger in _Rhamphorhynchus
phyllurus_ are exceptionally short as compared with other species.
Everyone agrees that the species called longicaudus is a distinct one,
so that it is chiefly in slight differences in the proportions of
constituent parts of the skeleton that the types of the Rhamphorhynchus
are distinguished from each other. I cannot quite concur with either
Professor Zittel (Fig. 58, 3) or Professor Marsh (Fig. 58, 2) in the
expansion which they give to the wing membrane in their restorations;
for although Professor Zittel represents the tail as free from the hind
legs, while Professor Marsh connects them together, they both concur in
carrying the wing membrane from the tip of the wing finger down to the
extremity of the ankle joint. I should have preferred to carry it no
further down the body than the lower part of the back, there being no
fossil evidence in favour of this extension so far as specimens have
been described. Neither the membranous wings figured by Zittel nor by
Marsh would warrant so much body membrane as the Rhamphorhynchus has
been credited with. I have based my restoration (p. 161) of the skeleton
chiefly on _Rhamphorhynchus phyllurus._
THE SHORT-TAILED TYPES
The Pterodactylia are less variable; and the variation among the species
is chiefly confined to relative length of the head, length of the neck,
and the height of the body above the ground. The tail is always so short
as to be inappreciable. Many of the specimens are fragmentary, and the
characters of the group are not easily determined without careful
comparisons and measurements. The bones of the fore limb and wing
finger are less stout than in the Rhamphorhynchus type, while the femur
is generally a little longer than the humerus, and the wing finger is
short in comparison with its condition in Rhamphorhynchus. These
short-tailed Pterodactyles give the impression of being active little
animals, having very much the aspect of birds, upon four legs or two.
The neck is about as long as the lower jaw, the antorbital vacuity in
the head is imperfectly separated from the much larger nasal opening,
the orbit of the eye is large and far back, the teeth are entirely in
front of the nasal aperture, and the post-orbital vacuity is minute and
inconspicuous. The sternum is much wider than long, and no specimens
give evidence of a manubrium. The finger bones progressively decrease in
length. The prepubic bones have a partially expanded fan-like form, and
never show the triradiate shape, and are never anchylosed. About fifteen
different kinds of Pterodactyles have been described from the Solenhofen
Slate, mostly referred to the genus Pterodactylus, which comprises forms
with a large head and long snout. Some have been placed in a genus
(Ornithocephalus, or Ptenodracon) in which the head is relatively short.
The majority of the species are relatively small. The skull in
_Ornithocephalus brevirostris_ is only 1 inch long, and the animal could
not have stood more than 1-1/2 inches to its back standing on all fours,
and but little over 2-1/2 inches standing as a biped, on the hind limbs.
A restoration of the species called _Pterodactylus scolopaciceps_,
published in 1875 in the _Illustrated London News_ in the position of a
quadruped, shows an animal a little larger, with a body 2-1/2 inches
high and 6 to 7 inches long, with the wing finger 4-1/2 inches long.
Larger animals occur in the same deposit, and in one named
_Pterodactylus grandis_ the leg bones are a foot long; and such an
animal may have been nearly a foot in height to its back, standing as a
quadruped, though most of these animals had the neck flexible and
capable of being raised like the neck of a Goose or a Deer (p. 30), and
bent down like a Duck's when feeding.
[Illustration: FIG. 59. RESTORATION OF THE SKELETON OF _PTENODRACON
BREVIROSTRIS_
From the Solenhofen Slate. The fourth joint of the wing finger appears
to be lost and has not been restored in the figure. (Natural size)]
The type of the genus Pterodactylus is the form originally described by
Cuvier as_ Pterodactylus longirostris_ (p. 28). It is also known as _P.
antiquus_, that name having been given by a German naturalist after
Cuvier had invented the genus, and before he had named the species.
There are some remarkable features in which Cuvier's animal is distinct
from others which have been referred to the same genus. Thus the head is
4-1/2 inches long, while the entire length of the backbone to the
extremity of the tail is only 6-1/2 inches, and one vertebra in the neck
is at least as long as six in the back, so that the animal has the
greater part of its length in the head and neck, although the neck
includes so few vertebrae. Nearly all the teeth--which are few in number,
short and broad, not exceeding a dozen in either jaw--are limited to the
front part of the beak, and do not extend anywhere near the nasal
vacuity. This is not the case with all.
In the species named _P. Kochi_, which I have regarded as the type of a
distinct genus, there are large teeth in the front of the jaw
corresponding to those of Pterodactylus, and behind these a smaller
series of teeth extending back under the nostril, which approaches close
to the orbit of the eye, without any indication of a separate antorbital
vacuity. On those characters the genus Diopecephalus was defined. It is
closely allied to Pterodactylus; both agree in having the ilium
prolonged forward more than twice as far as it is carried backward, the
anterior process covering about half a dozen vertebrae, as in
_Pterodactylus longirostris_. A great many different types have been
referred to _Pterodactylus Kochi_, and it is probable that they may
eventually be distinguished from each other. The species in which the
upper borders of the orbits approximate could be separated from those in
which the frontal interspace is wider.
[Illustration: FIG. 60. CYCNORHAMPHUS SUEVICUS FROM THE SOLENHOFEN
SLATE SHOWING THE SCATTERED POSITION OF THE BONES
_Original in the Museum at Tuebingen_]
[Illustration: FIG. 61. CYCNORHAMPHUS SUEVICUS
RESTORATION SHOWING THE FORM OF THE BODY AND THE WING MEMBRANES]
It is a remarkable feature in these animals that the middle bones of the
foot, termed instep bones or metatarsals, are usually close together, so
that the toes diverge from a narrow breadth, as in _P. longirostris_,
_P. Kochi_, and other forms; but there also appear to be splay-footed
groups of Pterodactyles like the species which have been named _P.
elegans_ and _P. micronyx_, in which the metatarsus widens out so that
the bones of the toes do not diverge, and that condition characterises
the Ptenodracon (_Pterodactylus brevirostris_), to which genus these
species may possibly be referred. Nearly all who have studied these
animals regard the singularly short-nosed species _P. brevirostris_ as
forming a separate genus. For that genus Soemmerring's descriptive name
Ornithocephalus, which he used for Pterodactyles generally, might
perhaps have been retained. But the name Ptenodracon, suggested by Mr.
Lydekker, has been used for these types.
[Illustration: FIG. 62. _CYCNORHAMPHUS SUEVICUS_
Skeleton restored from the bones in Fig. 60]
[Illustration: FIG. 63. RESTORATION OF SKELETON CYCNORHAMPHUS FRAASI
SHOWING THE LIMBS ON THE RIGHT SIDE
_From a specimen in the Museum at Stuttgart_]
[Illustration: FIG. 64. CYCNORHAMPHUS FRAASI
RESTORATION OF THE FORM OF THE BODY]
Some of the largest specimens preserved at Stuttgart and Tuebingen have
been named _Pterodactylus suevicus_ and _P. Fraasii_. They do not
approach the species _P. grandis_ in size, so far as can be judged from
the fragmentary remains figured by Von Meyer; for what appears to be the
third phalange of the wing finger is 7-1/2 inches long, while in these
species it is less than half that length, indicating an enormous
development of wing, relatively to the length of the hind limb, which
would probably refer the species to another genus. _Pterodactylus
suevicus_ differs from the typical Pterodactyles in having a rounded,
flattened under surface to the lower jaw, instead of the common
condition of a sharp keel in the region of the symphysis. The beak also
seems flattened and swan-like, and the teeth are limited to the front of
the jaw. There appear to be some indications of small nostrils, which
look upward like the nostrils of Rhamphorhynchus, but this may be a
deceptive appearance, and the nostrils are large lateral vacuities,
which are in the position of antorbital vacuities, so that there would
appear to be only two vacuities in the side of the head in these
animals. The distinctive character of the skeleton in this genus is
found in the extraordinary length of the metacarpus and in the complete
ossification of the smaller metacarpal bones throughout their length.
The metacarpal bones are much longer than the bones of the fore-arm, and
about twice the length of the humerus. The first wing phalange is much
longer than the others, which successively and rapidly diminish in
length, so that the third is half the length of the first. There are
differences in the pelvis; for the anterior process of the ilium is very
short, in comparison with its length in the genus Pterodactylus. And the
long stalk of the prepubic bone with its great hammer-headed expansion
transversely in front gives those bones a character unlike other genera,
so that Cycnorhamphus ranks as a good genus, easily distinguished from
Cuvier's type, in which the four bones of the wing are more equal in
length, and the last is more than half the length of the first; while
the metacarpus in that genus is only a little longer than the humerus,
and much shorter than the ulna. The _Pterodactylus suevicus_ has the
neck vertebrae flat on the under side, and relatively short as compared
with the more slender and narrower vertebrae of _P. Fraasii_.