between the brain-cavity and the fore-part of the jaw. The form and
condition of the orbits, nares, and of the space between them, vary
in German specimens. Some Birds and certain Ruminants, such as deer,
the giraffe, &c., have an interspace between the orbits and nares
corresponding to that in some Pterodactyles, but no such perforation
is found in living reptiles. In mammals it appears to be surrounded
by the frontal, nasal, lachrymal, and often by the maxillary bone.
In birds the bones appear to be the lachrymal, nasal, maxillary and
premaxillary, as is the case with Pterodactyles, except that the nasal
bones would seem sometimes to be excluded. The chief peculiarity of
the Pterodactyle skull in this region is made by the malar bone (and,
according to some authors, the maxillary also) sending up a process to
meet the lachrymal. This is not seen in birds, but is characteristic of
many mammals and reptiles.
The premaxillary bone is single, as in birds and Iguana; but it appears
to attain as great a development as in birds, and to occupy the portion
of the jaw which among reptiles and mammals is made by the maxillary
bone. Owing to the great development of the premaxillary bones, the
exterior nares are placed far back toward the middle of the skull as in
birds, and not near the tip of the snout as in living reptiles and most
mammals.
The orbits in Pterodactyles are surrounded with bone, as is commonly
the case with mammals and reptiles. Among birds a complete orbit
is seen among the parrots, in which it is completed below by a
prolongation of the outer posterior corner of the frontal, which would
correspond to the post-frontal bone, and by the lachrymal bone. Thus
the malar bone, which in most mammals and reptiles forms an important
part of the lower margin of the orbit, is in birds entirely excluded.
In Pterodactyles the malar bone is placed between the lachrymal and the
post-frontal process of the frontal bone.
The quadrate bone in German Pterodactyles, instead of being vertical
as in birds, stretches obliquely forward below the malar bone, so that
the articulation for the lower jaw is brought forward to be under the
middle of the orbit. In _Pterodactylus Kochi_ and in other species
there appears to be a process, or small separate triradiate bone,
comparable to a diminished lacertian post-frontal, and homologous
with the post-frontal process of the parrots. Its upper branch meets
the frontal. In some genera the front appears to meet the malar. The
lower branch goes to the front of the quadrate bone, and the backward
branch goes to the squamosal immediately above the articulation for
the quadrate bone. Thus it is a post-frontal bone resembling that
of the Iguana, but modified and adapted to a cranium like that of a
bird. Its form and size in the different genera are very variable. No
similar development is seen among mammals, where the post-frontals have
probably ceased to exist. It is a carious point of resemblance, but
from the other resemblances to Iguana being so few it is robbed of much
of its force as a mark of affinity, and becomes of interest chiefly as
an evidence of independent persistence of structures.
The pterygoid and palatine bones approximate to those of bird and
lizard in Pterodactylus crassirostris. And the bones in Pterodactylus
suevicus, which Quenstedt names vomera, should rather have been named
palatines. There is a bone in Goldfuss' specimen, between the malar and
palatine, which he identifies with the transverse bone, but it is not
seen in any other specimen.
The ribs sometimes appear to articulate by single heads, but in P.
crassirostris they are apparently articulated as in the Crocodile.
Some species show abdominal ribs like those of some reptiles; but the
segments of the mammalian sternum and abdominal ribs are to be regarded
as homologous structures. The vertebræ offer considerable variety in
size and shape, but the greatest variation in number is seen in the
tail, which is sometimes stiff and long, and sometimes short. The
pelvic bones show a large amount of variation in different genera,
often appearing to be crocodilian, sometimes lacertian, sometimes
mammalian. In the aim the humerus is variable in the length of the
radial crest, and the metacarpus also varies in length.
When the external similarity of the skeletons of birds is borne
in mind, it is impossible, without disregard of classification
altogether, to place animals differing so widely as do the different
Ornithosaurians in the few genera in which they are at present packed.
CLASSIFICATION.
The orders of Ornithosaurians may be established hereafter. Under the
name Pterosauria, Prof. Owen founded one order which has for its type
the Pterodactylus longirostris.
Von Meyer proposed to separate this order into two groups, one with
two phalanges in the wing-finger, of which Ornithopterus is the only
example, forming his Diathri; while the other group, Tetrathri,
or those "with four fingers, comprised all other Pterosaurians.
The Tetrathri he again subdivided, following out, as he states,
the suggestion of Munster and Goldfuss, into _Dentirostres_ or
such Pterodactyles as have the jaws furnished with teeth to their
anterior termination; and the _Subulirostres_, or such as want teeth
at the extremities of the jaws. To the former group he left the name
Pterodactylus, and to the latter was given the name Rhamphorhynchus.
Von Meyer says that he might easily have made a few more species, as
will be evident to those who inspect his plates, but he "believes
that the students of living animals go too far in their tendency to
subdivide:" a fancy that, if indulged in by Palæontologists, would have
the effect of restoring the old Linnæan groups; and a complaint which,
although often heard, has usually come from those who do not readily
discern and appraise classificational characters. In Palæontology
genera are sometimes co-extensive with orders, while species often mean
genera. It may be wearisome to the collector to be lured on to follow
the devious ways of a science, but Palæontology, the source whence
the mysteries of existing nature must unravel their meaning, is the
handmaid of all nature's truths which have been buried in evolving the
existing creation; and a duty devolves upon Palæontologists to make the
past an inseparable part of the present, by applying to the two the
same scientific method.
A year previous to the formation of Owen's Pterosauria, Bonaparte named
the Order Ornithosaurii, and divided it into a family--Pterodactylæ,
and a sub-family Pterodactylinæ.
Fitzinger (_Systema Reptilium_, 1843) also used the same ordinal name,
and recognized three genera--
_Pachyrhamphus_, of which the type is Pterodactylus crassirostris
(Gold.).
_Pterodactylus_, with the type P. longirostris (Cuv.).
And _Ornithocephalus_, with the type O. brevirostris (Sömm.).
These and other attempts at classification all endeavour to subdivide
Ornithosaurians by the head or by the tail. Other characters for
primary divisions may be obtained from the pelvis.
In the majority of German Pterodactyles the ilium extends for a long
distance in front of the os pubis, and only for a very short distance
behind the large ischium; and the small pubis from its anterior margin
gives attachment to a large prepubic bone, which resembles in form
the os pubis of the Crocodile[Z], and is unlike that of the Monotreme.
These appear to include the long-legged animals with short tails, at
present called Pterodactyles, and form a well-marked family or order.
[Footnote Z: Prof. Haughton, from a study of the bones and muscles,
came to the conclusion that the pubic bones of Crocodiles are the
marsupial bones.]
Another kind of pelvis is that in which the ilium extends a short
way in front of the acetabulum, in which the pelvic bones inclose a
much larger space. These include the Cambridge Ornithosaurians, the
Rhamphorhynchus, and the Dimorphodon, and form another well-marked
family.
These long-tailed Pterodactyles subdivide into three
sub-families--Rhamphorhynchæ, Dimorphodontæ, and Ornithocheiræ. The
four families may then be defined thus:
_Pterodactylæ_. Tail short. Hind-legs long. Ilium narrow, extending
far anterior to the acetabulum; ischium extending behind the
acetabulum. Epipubic bones ficiform. Head with the middle holes
large, often confluent with the exterior nares. Jaws toothed to the
anterior extremity.
_Rhamphorhynchæ_. Tail long and stiff. Hind-legs short. Pubis and
ischium small, oblique to ilium, which extends less far anteriorly
than in Pterodactylæ. Epipubic bones narrow and bent; they unite
mesially and form a three-sided bow in front of the pelvis. Head
with the middle holes and nares both small. Jaws never toothed to
the anterior extremity.
_Dimorphodontæ_. Tail long and stiff. Hind-legs long. Pubis and
ischium forming an expanded sheet of bone at right angles with the
narrow ilium, which extends as far behind as in front [prepubic
bones triangular (?) attached by the apex of the triangle]. Head
with the nares and middle holes large. Quadrate bone large. Jaws
with large teeth at the extremities, and small teeth behind. No
sacrum.
_Ornithocheiræ_. Tail long and flexible. Hind-legs short. Pelvis as
in Dimorphodontæ. [Epipubic bones with a small attachment, form
unknown.] Head with the quadrate bone small. Sacrum of not fewer
than three vertebræ.
In the Pterodactylæ the genera are--
_Pterodactylus_ (Cuvier), in which the exterior nares are at the
sides of the face, very large, and only partially, if at all,
separated by bone from the small middle hole of the head. The head
is elongated. The neck is long. Among others, it includes the
species P. longirostris, P. Kochi, P. scolopaciceps, P. longicollum.
_Ornithocephalus_ (Sömmerring), in which the anterior nares are
entirely separated from the middle holes of the head, both being
small, and the latter exceedingly small. The head is short The
neck is short. The large ischium appears to be excluded from the
acetabulum, and the ilium appears to extend less far forward than
in Pterodactylus[AA].
[Footnote AA: So far as can be judged from figures, it appears to have
but three bones in the wing-finger: what Cuvier regarded as a terminal
and fourth joint, the bone _n_, Pl. XXIII. fig. 7, _Oss. Foss._,
appearing to me to be the fibula of the tibia marked _e_. _s_ in the
same figure would be the terminal phalange, and _r_ the first phalange,
as may be proved by measuring them with those of the other hand,
so that a phalange is missing from between them. Both the terminal
phalanges appear to be hooked at the termination. Goldfuss figures
the phalanges so as to make the bone which appears to be fibula in
Sömmerring and Cuvier look like a fourth phalange.]
_Pachyrhamphus_ (Fitzinger). The nares are entirely separated from
the middle holes of the head; both are large. The head is thick
and massive. The prepubic bones meet mesially. No evidence of
the number of phalanges in the wing-finger. The quadrate bone
is massive, but has small attachment to the skull. Two sacral
vertebræ. Wing-metacarpal very short. The type is P. crassirostris
(Goldfuss).
_Cycnorhamphus_ (Seeley). Nares very small, looking upward from
a swan-like beak. The middle hole of the skull very large and
elongated and lateral. Neck long. Wing-metacarpal long. Four joints
in the wing-finger. Ilium widening in front. Epipubic bones meeting
mesially. The type is Pterodactylus suevicus (Quenstedt).
In the Rhamphorhynchæ at present there appears to be but one genus
known:
Rhamphorhynchus (von Meyer). The nares and middle holes are both
small, ovate, of nearly equal size, and close together at the side
of the head in front of the orbit.
In the Dimorphodontæ the only genus is
_Dimorphodon_ (Owen). It has the nares enormously large. The middle
holes are also large.
In the Ornithocheiræ the genus is
_Ornithocheirus_ (Seeley), in which teeth are prolonged anterior to
the muzzle, and the palate has a longitudinal ridge.
With the osteological illustrations of the Ornithosauria are arranged
some premaxillary bones, which show varieties of form of the snout.
These variations of shape serve easily to indicate different species.
And the following memoranda from those specimens and other specimens
in the drawers form a synopsis of the species of the Cambridge genera,
which may hereafter be fully elucidated from the copious materials in
the series of associated remains.
I.
Ornithocheirus Sedgwicki (Owen).
Case. Comp. Tablet. Specimen.
=J= _c_ 13 2
The fragment is 2-7/8ths inches long, with the elliptical teeth
opposite to each other, 6 on a side on the palate, and one pair in
front. The first three teeth are large; behind these the teeth are
about half the size. The palate is gently convex, with a faint median
ridge, and measures from side to side over the fourth and subsequent
sockets 13/16ths of an inch. The height of the jaw at the fourth socket
1-1/4 inch. The sides converge to an acute rounded rostral keel. The
jaws appear to have been long. The anterior termination is vascular.
The rostral keel figured by Owen Pl. I, fig. 1 _d_, in the 1st Supt.
_Cret. Reptiles_, is not square as represented there, but rounded;
the sides converge more acutely, and at the ridge the keel is not
half so wide as the figure makes it. The enormous size of the third
tooth-socket is partly due to the cracked bone having absorbed
more phosphate of lime than it could hold, and extended the cracks
to fissures. The type specimen shows that there was another pair
of sockets in front of, but quite close to, those which appear to
terminate the lower jaw.
II.
Ornithocheirus Cuvieri (Bowerbank).
Case. Comp. Tablet. Specimen.
=J= _c_ 15 1-3
A portion of a premaxillary bone fractured at both ends, and two inches
long, corresponds with Dr Bowerbank's fossil figured Pl. XXVII. fig. 1,
3, 4, in the Palæontographical volume for 1851. The palate is just as
wide; the median ridge, the same; the teeth the same in shape and as
far apart. The jaw is of the same depth, but does not deepen so rapidly
behind. The only other difference is that the sockets of the teeth are
less prominent on the sides, and appear to look more directly down.
The ridge in which the converging sides meet is well rounded in a
dentary bone which may have pertained to this species. In the space
of two inches and a quarter are 5 teeth, the posterior four extending
over two inches, the other pair being in front. The palatal surface is
3/4 of an inch broad behind the third tooth, and rather more than 5/8
of an inch broad behind the fourth tooth. The length of the 4th or of
the 5th sockets is two-thirds that of the second or third. In front of
the 5th tooth, the jaw is an inch deep, and it tapers in a curve to
the anterior end. The teeth behind the third have interspaces greater
than the length of the sockets; that between the 4th and 5th being 3/8
of an inch, while the socket only measures a quarter of an inch long.
Behind the 2nd socket commences the palatal groove, broad in fronts but
narrowing behind; and its sides instead of diverging as in the type,
are concave so as to form a channel like a straightened _Siliquaria_
shell. The halves of the palate bevel off so as to make a right angle
with each other, and greater angles with the flat sides.
III.
Ornithocheirus machærorhynchus (Seeley).
Case. Comp. Tablet. Specimen.
=J= _c6_ 35 1
Dentary bone. Broken at both ends, and wanting all its teeth, this
interesting fossil shows the suture where its whole length rests on the
angular bone which almost reached to the termination of the beak, quite
unlike what is seen in any German Pterodactyle.
It is a narrow mandible, less than three quarters of an inch wide, with
the alveolar margins parallel. The palatal surface 1-1/2 inch long,
is divided into 3 equal strips; the middle one being a deep glossal
groove, slightly narrowing in front, and deepening behind, made by two
inclined flat surfaces. The lateral strips are horizontal behind, and
in front slope a little outward. The tooth-sockets are oval, directed
outward, and as long as the interspaces, though these seem to get
longer behind. In an inch and a quarter there are four teeth. Below
the teeth, the sides of the jaw are compressed: though nearly parallel
at the hinder fracture, the flattened surfaces approximate in front
till they meet in a sharp keel, which appears to make an acute angle
of about 45° with the palate; and below, where the jaw is an inch deep
extends for half an inch in front of the suture with the angular bone:
this suture is straight and irregularly concave, and in an inch and a
quarter approximates to within 5/8ths of an inch of the palate.
IV.
Ornithocheirus tenuirostris (Seeley).
Case. Comp. Tablet. Specimen.
=J= _c2_ 12 1
Middle part of a premaxillary bone fractured behind and in front,
slightly distorted by compression; it is 2-1/8th inches long, and
nearly resembles _O. compressirostris_ (Owen). The palate is about
1/2 an inch wide in front, and 5/8ths of an inch wide behind; it is
compressed mesially into a strong angular keel, between which and
the teeth there is a shallow groove on each side. The groove dies
away behind, and the converging parts of the keel occupy the whole
space between the teeth. The teeth-sockets are small, elliptical, not
opposite to each other, and placed along a distinct flattened tooth
area, which looks downward and outward and separates the palate from
the side of the jaw. The first pair of sockets preserved are almost
3/16ths of an inch long and 1/16th of an inch wide. The interspace
between that tooth and the next tooth behind is 7/16 of an inch.
Separated by similar interspaces, behind these on one side are two
sockets, and on the other side one socket. The sides are flattened in
front, and convex behind, (making the section of the jaw lanceolate);
they are compressed and round into a narrow rostral keel. The height
from the palatal ridge to the rostral keel in front is 11/16ths of an
inch; behind it is fractured, but the height was probably 14/16ths of
an inch.
The palatal keel, distance of the teeth, and proportions of the jaw,
distinguish it from O. compressirostris (Owen).
V.
Ornithocheirus Oweni (Seeley).
Case. Comp. Tablet.
=J= _c_ 20
The small piece of premaxillary on which this species is founded
indicates a small animal, and nearly resembles the jaw of _O. microdon_.
It is scarcely an inch long; nearly 9/16ths inch high behind, and
nearly 7/16ths of an inch high in front, so that it tapers very
rapidly, and could scarcely have been an inch longer in front.
The nose is well rounded, but the sides are a little concave, and
become well pinched in in the middle, behind, showing the near approach
as I think to the nostril.
The palate half an inch broad, is divided into two concave channels by
the strong and sharp median ridge, which projects below the alveolar
margins. The dental margins are not rounded as in _C. microdon_, but
flattened, making more than a right angle with both the outer side-wall
and palate. The interspaces between the teeth are rough, looking as
though they had supported minute teeth. The alveolar margin is a
tenth of an inch wide; along it are the perfectly circular sockets, a
sixteenth of an inch in diameter. There are 3 sockets between 5/8 of an
inch, so that they are separated by 3 times their diameter. The palate
is obliquely impressed with blood-vessels running forward to the teeth
from the median ridge.
The points in which this jaw differs from that of _O. microdon_ are
that in this species the teeth are circular instead of being oval; that
the interspaces here are as long as in that species, though this jaw
is only two-thirds the width; that instead of having a sharp keel on
the upper surface, this has a well rounded roof. That though the jaw
is scarcely higher than it is wide, it shows strong furrows running up
to the nares, while in _O. microdon_, though the proportions are the
same, the sides are perfectly flat without trace of pinching in, while
the line of the nasal opening is indicated by a faint furrow running
all along the jaw. And lastly it differs in size, which, where the
sutures are lost, may be important in discriminating forms.
VI.
Ornithocheirus microdon (Seeley).
Case. Comp. Tablet. Specimen.
=J= _c_ 29 1-2
Premaxillary bone. The fossil is nearly 1-3/4ths inch long, and at the
proximal end, where it is less than 3/4ths of an inch high, has flat
sides, which converge to form a keel which is depressed anteriorly
and rounded so that where fractured in front the bone is 7/16ths of
an inch deep. The palatal surface contains two wide concave channels,
between which descends a sharp median ridge, which behind becomes more
prominent than the alveolar border.
The palate is 5/8ths of an inch wide. The alveolar margins are
compressed and rounded. The small tooth-sockets are oval, and four are
contained in 1-1/8th inch; they look downward.
There is a small tip of a jaw associated with this fossil, which is so
like that it might be part of the bone broken off before fossilization.
It corresponds in every way except that the teeth are closer. In this
terminal lanceolate fragment there are in 5/8ths of an inch four teeth.
The snout is terminated by two, which are close together.
VII.
Ornithocheirus Huxleyi (Seeley).
The only specimen of this species yet known is the greater part of a
dentary bone contained in the Museum of the Geological Survey. An inch
and 1/4 long and 3/4ths of an inch wide, it is less than half an inch
deep: the sides slowly converge towards the front, and it appears to
have had an obtusely lanceolate beak. The under surface is convex, too
inflated for trace of a keel, and tapers to the end of the beak, which,
with the left alveolar margin is abraded. The palatal surface is smooth
at its front end, but two diverging ridges soon arise and form the
boundary of a posteriorly deepening mesial channel, which is a quarter
of an inch wide at the fracture. These ridges too, which are parallel
with the compressed and rounded alveolar margins, convert the lateral
spaces into shallow channels. The right side shows the sockets of 3
small oval teeth separated by interspaces wider than teeth. A tooth and
two interspaces measure 7/16ths of an inch.
The only cretaceous Pterodactyle which this at all resembles is _O.
microdon_, but the palate is wider than in that species; the sides
converge towards each other more rapidly, as though it belonged to a
species with a shorter snout.
I am indebted to Prof. Huxley for the opportunity of making a notice of
this species.
VIII.
Ornithocheirus oxyrhinus (Seeley).
Case. Comp. Tablet. Specimen.
=J= _c2_ 13 1
This well-marked species is a portion of a premaxillary bone 1-1/4 inch
long, fractured behind and in front. The palate is half an inch wide;
its two halves are inclined to each other at a considerable angle, and
where they meet form a more prominent keel. The tooth-sockets look more
outward than downward, are nearly circular, separated by interspaces
as long as the sockets; three sockets and two interspaces measure one
inch. The jaw is about 5/8ths of an inch high in front, and about
1/16th of an inch higher behind. The sides are flat and converge like
the sides of a wedge to a sharp rostral keel.
IX.
Ornithocheirus xyphorhynchus (Seeley).
I have seen but one example of this form. It has lost much of the outer
layer of bone, and shows on the sides impressions like tooth-marks from
an eater of Pterodactyles. A groove which has some appearance of being
due to fracture traverses each side, but the specimen is symmetrical,
and has its characters in no way changed by the accident.
It is a portion of a lower jaw of a long-beaked Pterodactyle of the
_O. Sedgwicki_ type, with parallel sides, and the rounded basal ridge
nearly parallel with the palate.
The fragment is two inches long, showing four large and obliquely set
sockets in If inch. The tooth-sockets are on the outer two-thirds of
the palate, and looked forward, upward, and outward The interspaces
each measure 5/16ths of an inch.
Each half of the palatal surface which is 5/16 of an inch wide,
inclines to the other half at a right angle, being parted by a narrow
groove; the diameter of the jaw is half an inch.