Case.Comp.Tablet.Specimen.Jc101—3
Frontal(?) Owen.Palæontographical, 1859Pl. 4, fig. 6, 7, 8.
In 1859 Prof. Owen described with doubt as the Frontal of Pterodactyle, a symmetrical bone. A smaller but more perfect specimen has since been obtained for the Woodwardian Museum; and a fragment of intermediate size is in the rich collection of the Rev. T. G. Bonney. From the descriptions already given it is impossible for it to be the frontal. Thereis no proof that it is a skull bone. If of Pterodactyle the compressed lateral spaces could only be part of the nasal passages, or the impressions of a palatine or pterygoid articulation. And as the external surface of every specimen is keeled, and as the palatal surface of the upper jaw of every known Greensand Pterodactyle is keeled, and as the concavities slightly converge to the keel, it might be a bone from the under side of the head,—the vomer.
The smallest specimen is a compressed sub-semicircular bone 11/4inch long,9/16inch high, and a1/4inch thick. The under surfaces converge to form a strong keel, which is flattened off behind. Above this, the posterior third of the bone is compressed obliquely to half the thickness, as though a bone had over-lapped this area on each side. If the oval spaces are nares, that bone might have been the pterygoid or palatine. Three-fifths of the remainder of the bone are taken up by the smooth oval depressions, which might be the inner walls of the nares; and above this is a margin of bone widening into the triangular compressed part in front, which, if the fossil is rightly determined, must have fitted into the posterior end of the maxillary or anterior end of the palatine bones.
A specimen collected by the Rev. T. G. Bonney is preserved on the sacral side of a leftos innominatumwith the keel downward. It appears to show a sutural surface from which an anterior part has come away. And if this specimen is compared with the neural arch of the sacral vertebraJ.c.4.1, it will be found to correspond entirely. It is not impossible thatc.10.1, 2 may be vomerine, andc.10.3 sacral, but there are no distinctive characters between the specimens to warrant such a determination.
Case.Comp.Tablet.Specimen.Jc111—4
QUADRATUM.Pl. 11.and Quadrato-Jugal.
In the Woodwardian Museum are two distal ends of the quadrate bone and two other fragments showing the quadrato-jugal with it.
Quadrate.The smallest specimen is1/2an inch over the articular surface for the lower jaw and a quarter of an inch thick. It is concave from side to side in front where it shows a large pneumatic foramen near the basal end; it is bent from the articulation a little backward. It is convex behind; and between the foramen and the articulation sends inward and forward a great wing like that of the quadratum in birds. The specimens are broken short off and do not show any articulation above, where the bone contracts.
The distal articulation is double, like two long cones placed together; that in front having the base outward, while the hinder one has the base on the inner side. The largest specimen, which is much broken, shows the articulation half an inch thick.
Quadrato-jugal.This is a thin flat squamous bone, apparently of a transverse diamond shape, which is anchylosed to the anterior lateral margin of the quadrate, at right angles to the articulation. The lower margin is straight, as is the upper anterior margin, which appears to have received the malar bone above.
The upper posterior side is broken, but shows a large foramen near to the side of the quadrate. The base of the diamond is at the articulation, and at its apex is a small fragment of smooth surface, either part of a foramen, or the orbit of the eye.
In this specimen the articulation, which is broken, is about3/4of an inch wide,3/8of an inch thick. The remaining piece of the quadrate is an inch long. The quadrato-jugal is an inch and3/16high, and between its broken ends 13/4inch long. It is thick and strong where joining the quadrate, but the rest of the bone is about an1/8th of an inch thick.
The quadrate bone is Avian in possessing a pneumatic foramen, and Avian in the form of so much of the distal end as is preserved, and in the articulation for the lower jaw. The process which it sends inward on the inside is probably for the pterygoid bone, after the manner of Birds. Before anchylosis with the quadrato-jugal bone set in, as may be seen inJ.c.11.4, the union was made by a hemispherical knob on the outside of the quadrate, as inGallus domesticus. The squamose quadrato-jugal is a distinctive character.
Case.Comp.Tablet.Specimen.Jc141—2
?PTERYGOID END OF PALATINE BONE.Pl. 12.
This determination is conjectural. Its form is such as would make it probable that it is part of the head. A more perfect specimen is seen inJ.c.1.2.7.
The best specimen is a compressed sub-quadrate fragment of bone terminating at one end in a long reniform articular surface, and at the other end in a fracture where the bone is rapidly thickening. A side, regarded as the outer one, is flattened, being slightly concave in length, and slightly convex from side to side. The form of the inner side of the bone is determined by the inward curve of the thick part of the articular surface, which sends a rounded ridge obliquely on to the side, so that while it is concave from side to side at the articulation, at the fracture it is convex from side to side. All the specimens are large, the articulation being not less than an inch long.
PREMAXILLARY BONESPl. 12.
appear to be developed as in birds. An account of their structure will be found in the notes on the species,page 112.
Case.Comp.Tablet.Specimen.Jc121—6
OS ARTICULARE AND PROXIMALEND OF LOWER JAW.Pl. 12.
Prof. Owen has described in a 'Palæontographical' monograph the proximal end of a mandible in which the sutures are obliterated. But there is one specimen of a young right ramus showing the inner and under part of the mandible to be the surangular bone which unites with the angular or outer bone by a longitudinal and vertical suture traversing on the inner side the great upper groove; and on the surangular the greater part of the articular bone rests. The articulation is strong and double, consisting of a deep transverse hollow, bounded by a strong over-locking ridge in front and a slight ridge behind; and this area is divided into two tapering furrows by a strong oblique androunded crest, which passes from behind inward and forward. Just behind the articulation is a ?pneumatic aperture, and then the upper surface tapers to the under surface, forming a heel, of which one specimen measuring an inch deep on the inside of the articulation has3/4of an inch still left and is more than1/4inch thick at the fracture. In a specimen belonging to the Rev. T. G. Bonney the outside of the jaw is11/16of an inch deep, and under the articulation5/16of an inch deep. The articular area is3/4of an inch wide and6/16of an inch long.
Seven specimens indicate four species.
The proximal end of the lower jaw is entirely Avian. The pneumatic aperture, as in birds, is placed behind the articulation, which is shaped as in many birds. Commonly in Ornithosaurians the bones are anchylosed and all trace of sutures obliterated, as in most birds. In the Goose, however, the six elements of each side are sometimes as readily separated as in reptiles. And in some Pterodactyles the bones separate.
THE DENTARY BONEPl. 12.
The dentary bone consists of a single piece, as in birds and chelonians; and differs from both in being provided with teeth. It is described under the species O. machærorhynchus,page 113.
Case.Comp.Tablet.Specimen.Jc171—39
THE TEETH.Pl. 12.
The first three teeth are usually larger than those which are placed behind them, in this respect rather resembling some fossil reptiles than Dolphins, and presenting a character like that seen in the Dimorphodon. They are placed in oblique oval sockets. They have a single fang like Cetaceans, Edentates, Reptiles, and like the premaxillary teeth of Mammals. Cambridge specimens of jaws are not sufficiently perfect to show whether the teeth are limited to the premaxillary bone; but this appears to be the case inPterodactylus crassirostris(Goldf.), and probably inOrnithocheirus compressirostris(Owen), [Palæontographical Society, 1851, Pl. 27], and is so regarded by Professor Owen in his later writings. Yet the significance of this fact seems to have been forgotten, and Cuvier's dictum about their teeth still has influence. He says,"The teeth, by which the examination of an animal ought always to be commenced, here present nothing equivocal. They are all simple, conical, and nearly alike, as in the crocodiles, monitors, and other lizards." But, on the one hand, the Dolphins demonstrate that a mammal might have similar teeth even in the maxillary bone; and, on the other hand, since teeth in the premaxillary bone always are single-fanged, and commonly have a simple sub-conical crown, there is absolutely no evidence in the teeth of the affinities of the animal, which, so far as this portion of its economy went, might as well have been a fish or a mammal as anything else. In the succession there is nothing very distinctive. In the Crocodile one tooth comes up under another, as is commonly the case with mammals; and in mammals the fangs of the old teeth are often partially absorbed so that the teeth drop out into the mouth. In the Pterodactyle the new teeth came up on the inner side, as in the Ichthyosauria—a tribe of animals as singular in their affinities as the Ornithosauria. Occasionally specimens show a small furrow on the inner side of the fang, indicating absorption, but there is nothing to show how many times the teeth were renewed: in the Dolphins there is but one set, and in Crocodiles the teeth are replaced many times. In form and size the teeth are very variable. They are directed obliquely forward, and are curved backward and inward. They taper in an elongate cone, compressed from side to side, flattened on the outside, moderately convex on the inside; rarely the sides meet in a ridge after the plan of Pliosaurus, Megalosaurus, Dakosaurus, &c.; more frequently the lateral margins round into each other. Usually the enamel is quite smooth, sometimes, as in No. 1, it is finely striated and wrinkled. Some teeth are nearly circular and some quite straight. The ovate fang contracts below, conically, and is closed, leaving a long hollow pulp-cavity in its interior. Nos. 9, 10 show the marks of the successional teeth on their inner sides. No. 11 appears to have had the crown slightly worn at the tip during the animal's lifetime. In transverse section of the crown the tooth structure resembles Ichthyosaurus, Cetaceans, and Bats. The dentine is filled with calciferous tubes which radiate as in Ichthyosaurus, and towards the centre of the tooth are seen in transverse section to present many angles, almost like radiated corpuscles. They are separated by interspaces of their own width, and run towards thecircumference, sometimes straight and sometimes wavy, parallel to each other. They send off branches usually at right angles which anastomose with the adjoining tubes. The dentine is in concentric layers, and shows layers of sub-circular cells as in the teeth of Mammals. The enamel is a thin transparent layer with fewer and finer tubes than the dentine.
The story of the structure of the Ornithosaurians of the Cambridge Greensand has now been told, and it only remains to gather up the threads of their affinities and determine the Pterodactyle's place in nature. But before doing so, so various in importance are the characters enumerated, that I would first offer a few remarks on the classificational value of characters among the Reptilia, with which Pterodactyles have been most commonly grouped.
The naturalist who only examines organisms now living on the earth, symbolizes to himself, by the term Reptile, a definite sum of characters, with definite subdivisions and subordinate grouping, to which the extinct types of life extricated from the rocks cannot entirely be adapted. When the fragmentary, and often isolated or ill-associated, bones of fossilized animals are contrasted with corresponding bones in the skeletons of Serpents, Crocodiles, Lizards and Turtles, not infrequently it is found that the characters attributed to different Ordinal groups are interlaced in a single individual with a type of organization peculiar to itself, and important as are the modifications of existing orders. These characters occasionally are grouped with others which in living animals had been deemed characteristic of Fishes, Amphibia, Birds, and Mammals.
The Reptilia of the Palæontologist is therefore a vast and provisional group, ever acquiring new characters, to which no diagnosis can be applied. And although certain empirical characters have served to allocate the specimens in their several orders, in general with sufficient accuracy, yet from the imperfect preservation of some of the remains, or the imperfect extent to which their structures are known, and the want of recognised canons by which to measure their relative values, it has not been possible todiscuss the relations of the several orders to each other or with the larger groups on which some of them impinge.
Classifications represent more or less faithfully the gradational increase in the sum of the characters of an organism, as well as the increase in importance that those character severally attain. Thus gathering, so far as may be, from the chaos of individuals,a common plan of structureson which the genus, order, or class is moulded from a less specialized group of organs. The fundamental structures of a vertebrate animal, so far as their persistent importance can be measured, are, those connected with
And these characteristics are for the most part so interlinked, that it becomes difficult to assign to one order of animals a relative superiority over another order; since when a single set of organs is prominently developed in one group it often happens that another set of organs has a like pre-eminence in an allied group. Thus among reptiles it might be considered that
Crocodileshave the best hearts, andTurtlesthe best lungs.
And since these structures in their functions severally modify and determine the use of other structures, the meaning that terms like Crocodilian and Chelonian really have is that they represent the aspect of Reptilian organization when seen through the specialization of respiration, or circulation of the blood. The soft parts thus determining the nutrition and function of the muscles and skeleton, anatomists in examining the bones of extinct animals are accustomed to reverse the order of their inferences, and infer from modifications of the skeleton what had been the characters of the soft and more vital structures.
On the presumed accuracy of this method of research rest many results of Comparative Anatomy. But since the shapes of bones are determined by the muscles as well as by inheritance, it is always to be remembered that a similar form of bone may obtain in different orders or classes of animals, as the result of a similar function in a special region of the body. Such resemblances arefamiliar to anatomists. Hence much caution is required from the Palæontologist to distinguish between the characteristics of a group, and the extent to which they may be modified by function. This distinction is the first principle of classification. But it is always difficult to estimate the importance of characters in fragments of bones or parts of skeletons, and the difficulty is increased by the fact that if what appears to be but a functional modification should pervade all the species, it becomes a characteristic of the group, and its power of modifying the other organs in a peculiar way has to be considered.
Thus for all practical purposes birds may be said to be characterized by wings, which almost acquire the dignity of class characters from their influence on the respiratory function. But in some birds it has been thought that no bone of the fore-limb was ever developed[V]; and the difference between such a phenomenon and the wing of a Swift, for example, is one almost of infinity, as compared with any other aspect that the anterior limb might have assumed. Therefore, since a bird may part with its fore-limbs and yet remain a bird, I infer that it might apply its fore-limbs to the ground, become a quadruped, and be a bird still. And if in this process the other structures remained unchanged, no one would regard the modification as more than an ordinal one. But should the vertebræ change also, or the pelvis, or the covering of the integument, or the jaws become toothed, then, although the heart and lungs and brain of the imaginary animal retained their class characters, the functional differences being more than those of an order would constitute it a sub-class.
[V]According to Prof. Owen, in Dinornis.
[V]According to Prof. Owen, in Dinornis.
In the same way it is conceivable that serpents may have existed with well-developed limbs, and if they retained their other characters the limbed forms would constitute a sub-order of serpents; but if to these characters they added a closed palate united to the cranium, they would constitute a new order of reptiles. A chelonian might be entirely deprived of its bony covering, and it would still be a chelonian, differing only as a separate family. So that structures which to the eye appear fundamental may be lost without affecting an animal's systematic position, just as animals while resembling each other in form may possess dissimilar organization.
Even with the living or typical Reptilia, naturalists are divided as to the number of ordinal groups into which they naturally fall. It is however generally agreed that the Amphibia or Dipnoa of Fitzinger, have no near affinity with the true reptiles. Milne-Edwards, Van der Hoeven and Agassiz make the remainder into three orders, as did Cuvier:
Chelonia,Sauria,Ophidia.
Stannius, Gray, Owen and Huxley, on the other hand, by dividing the Saurians make four orders, to which Dr Günther by his description of Sphenodon has given evidence of a fifth:
Crocodilia,Chelonia,Sauria,Ophidia,(Rhynchocephalia.)
De Blainville in a remarkable classification (1816), made three orders, Chelonians, Emydosaurians [crocodiles], and Saurophidians; the latter group being subdivided into Saurians and Ophidians.
In his "Handbuch der Anatomie der Wirbelthiere" Stannius unites the Crocodilia and Chelonia into a group called Monimostylica; while of the Sauria and Ophidia he makes another group called Streptostylica. Similar groups were made by Dr Gray, and named Cataphracta and Squamata. They are identical with the "cuirassed" and "scaly" reptiles of Dumeril and Bibron.
TheAstylica(Sphenodon) have no penis.
TheStreptostylicahave a double penis, lungs simplified at the distal end into a mere air-bladder, brains with a moderately elongated cerebrum, the palate mesially open, scales, leathery shell to the egg cut through by a tooth on the premaxillary bone.
TheMonimostylicahave a single penis, lungs well subdivided, ventricle of heart partly [turtles] or entirely divided [crocodiles], brains having the cerebrum broad or high, a closed palate, scutes, a calcareous shell to the egg.
Thus the chief differences between Turtles and Crocodiles on the one hand, and Lizards and Serpents on the other hand, are not so much in the fundamental vital structures, though theseundergo changes even in the families, as in the different ways in which the muscles and skeleton are modified. The typical lizards diverge widely from the crocodiles, and in those osteological features which admit of comparison they make at least as near an approach to the Chelonians. But leaving the limbs and pectoral and pelvic girdles out of consideration, lizards find their natural place side by side with the serpents.
Attempts have been made by Palæontologists to incorporate the new ordinal groups which they have been compelled to create for some fossils, along with the true Reptilia; but such a proceeding destroys the value of the term Reptile as a measure of a known organization. In the absence of knowledge of the brains of Dinosaurs, Ichthyosaurs, and Dicynodonts, their union with the Reptilia can only have a stagnating effect on Palæontology, for there is no proof that they are Reptiles in the same sense as are Crocodiles or Chameleons: while their bones being used as standards of Reptilian structure in comparisons, they adjudicate the place in nature of other animals by an authority which has never been established.
Before any inference can be drawn from the forms of bones in extinct animals, their relations to vital structures and to way of life must be known in animals which still live. This may give some clue both to their functional significance and to the extent to which they are inherited and not directly attributable to function. But an idea of the morphological value of the bones of living animals is only gained by comparing them with the remains of their extinct allies, tracing the now imitative structure back to its origin in a function which has ceased to be displayed.
Professor Owen in his "Comparative Anatomy of the Vertebrates" (1866) admits nine orders of Reptiles, five of which are extinct, some of the extinct orders being supposed to rank lower, while others are higher than the living types. They are arranged in this way,
Ichthyosauria,Batrachia,Labyrinthodontia,Ganocephala.
In what characters the Ichthyosaurs are lower than living reptiles I have been unable to discover. The palate may be better compared with a struthious bird than with a reptile; and the pectoral girdle may be better compared with the Ornithodelphia than with a reptile, while all the trunk-vertebræ have ribs such as are associated in living animals with a four-celled heart. But if it is a lower animal type than living reptilia, the student will ask, how much lower? does it descend to the Dipnoa, and prove to be the missing link between the Amphibia and Reptilia? and wherein is the evidence? Or does it not with Dicynodonts and Dinosaurs rather form an outlying class uniting the reptiles with the mammals.
In the same way, when Pterosauria and Dinosauria are placed above living reptiles, we are compelled to ask how much are they above, or what are the characters which bind them to the Reptilia at all? No satisfactory evidence has ever been adduced to show that the Dinosauria are Reptiles. And of the claim of the Pterodactyles to such a position, the facts detailed and now summarised will be the best evidence.
The highest structure shown in these remains is the brain-case. The cavity for the brain is in every respect like that in the skull of a bird. It resembles brains of a high type in having the cerebral lobes convex in front; since, in the lower mammals, there is a resemblance to reptiles in the conical form of the cerebrum; while the brains even of some of the placental mammals are not well distinguished from those of reptiles. Although the brain of the Ornithorhynchus is entirely mammalian,it is more like the brain of a reptile than is the brain of the Pterodactyle. No evidence of affinities could be adduced which would outweigh this. Taken by itself it would lead us to anticipate for the Pterodactyle those vital structures which birds have in common.
Next in importance to the brain are the pneumatic perforations in the bones. They are seen in the lower jaw, the quadrate bone, in the whole of the vertebral column, in all the bones of the fore-limb, excepting one or two fragments, in the scapula and coracoid, in the os innominatum, in the femur and in the tibia. In such of the bones as can be compared, the pneumatic perforation is usually situated in Birds as it is in Pterodactyles. In Birds the bones are filled with air through these perforations, and as a principle the greater the motion of the animal, the greater is the number of bones filled with air. This air is received from the air-sacs which receive it from the lungs, and return it through the lungs again. There is thus in birds a sort of supplemental lung-system, which circulates air through the body. Nothing of the kind exists in any other class of animals. The respiratory system in birds is more perfect and complex than in the other vertebrata, and, as a result, the temperature of the blood on the whole is hotter.
In Pterodactyles the reticulate character of the perforations proves that they were pneumatic, and supplied the bones with air. The fact that the bones were supplied with air, necessitates an elaborate system of air-sacs to furnish the supply. And the existence of these air-sacs speaks incontestably to bronchial tubes opening on the surface of the lungs to supply them, and to the existence of lungs essentially like those of birds. The outward and backward direction of the coracoid bones may indicate that the lungs were larger than in a bird.
The circulation of air through the bird's body has relation to rapid motion through the atmosphere, which necessarily produces more rapid respiration than would comparative quiescence. The same inference must be applied to the Pterodactyles. But rapid respiration only means more rapid oxidation of the blood, and conversion of the purple cruorine into scarlet cruorine,—that is, the conversion of venous blood into arterial blood. And if venous blood is converted into arterial blood by a lung-apparatuslike that of a bird, and with a rapidity like that in a bird, there must be a circulation of the blood as rapid as in birds. Such a circulation is only maintained by a heart with two auricles and two ventricles. Therefore Pterodactyles had the heart like that of birds and mammals.
Now, since the temperature of the blood is chiefly dependent on respiration and circulation, and Pterodactyles had respiratory and circulatory organs which in living animals produce hot blood, it results that they were hot-blooded animals.
Thus the heart and lungs are exactly such as would have been inferred from the brain, and, like it, they are avian. And so important are these vital structures all taken together, that the inference from them upon an animal's affinities would overbear all other evidence that could be adduced except reproduction; for they demonstrate the plan on which an animal was built, and are the motor power which enabled it to use its skeleton in a way that stamped upon it a peculiar form.
In the head such structures as are preserved conform with slight variations to the avian plan. Other Ornithosaurians show in the parts which are not preserved in Cambridge specimens some characters which are not avian; they are in part as much mammalian as reptilian, and in a few points entirely reptilian. But it might be misleading to take German specimens into consideration in forming an estimate of the Pterodactyles of the Cambridge Greensand, which were probably a different ordinal group, and may have had material differences in structure.
The vertebral column as a whole is distinctive.
The neck and sacrum are mammalian, and the tail reptilian. The procœlous vertebræ are characteristic of reptiles, but in some animals, as Chelonians, they vary in different regions of the body; and among amphibians the character is inconstant in genera nearly allied.
The hind-limb is in part mammalian and in part avian; if there be any reptilian characters in the foot, they are not less mammalian.
The os innominatum is avian and mammalian.
The pectoral girdle is avian.
The fore-limb is avian and mammalian.
The wing-finger is distinctive, though formed on the avian plan.
Thus, if with an avian basis some parts of the skeleton present points of agreement with reptiles, in other points there are resemblances with mammals not less characteristic. These phænomena do not show that in so far the animal is a mammal or a reptile, but only that mammals, ornithosaurians, and reptiles have had a common origin, and that while they have been differentiated so as to form separate classes they have severally retained characters which formerly were united in one class. It is a skeleton intermediate between reptiles and mammals, and well distinguished by mammalian, reptilian, and peculiar characters, from birds. It therefore forms a parallel group with birds, displaying the ornithic organization in a differently modified skeleton. Yet it differs more from existing birds than they differ among themselves, for the discrepancies are in points of structure in which all existing birds agree: they are in having teeth, in the procœlous centrum, in the separate condition of the carpal and metacarpal (and of the tarsal and metatarsal) bones; in having more than two bones in the fore-arm, in the sacrum formed of few vertebræ, in the expanded pubic (and prepubic) bones, in a long neck to the femur, and in the modification of the wing by the great development of the phalanges of one finger.
I therefore regard the Pterodactyles as forming a group of equal value with birds, for which group the name Ornithosauria is here used. It cannot form a separate class, because they have a fundamental organization in common; and it cannot form an order of birds, because its differences from birds are greater than those of an order. It is a group which itself probably includes several orders, and must constitute a sub-class, which finds its place in nature side by side with birds and between mammals and reptiles, thus:—
Restoration.
Of the form and size[W]of the animals from the Cambridge Greensand, an idea will best be given by a few measurements.
[W]There are Ornithosaurians hereafter to be described compared with which the largest at present known will seem diminutive. A vertebra of one such, from the Wealden, is contained in the British Museum (numbered 28632). The centrum alone is between 9 and 10 inches long and 8 inches deep. It is named Streptospondylus, but constitutes a new group of Ornithosaurians. Nothing so gigantic exists in the Woodwardian Museum. Another vertebra of the same or an allied genus has been figured by Prof. Owen as the tympanic bone of ?Iguonodon (Fossil Reptilia of the Wealden, Part 2, pl. 10).
[W]There are Ornithosaurians hereafter to be described compared with which the largest at present known will seem diminutive. A vertebra of one such, from the Wealden, is contained in the British Museum (numbered 28632). The centrum alone is between 9 and 10 inches long and 8 inches deep. It is named Streptospondylus, but constitutes a new group of Ornithosaurians. Nothing so gigantic exists in the Woodwardian Museum. Another vertebra of the same or an allied genus has been figured by Prof. Owen as the tympanic bone of ?Iguonodon (Fossil Reptilia of the Wealden, Part 2, pl. 10).
In the species Ornithocheirus nasutus (Seeley),J.c.2.11.1:
The premaxillary extends for 6 inches without reaching the nares.
The lower jaw is3/4of an inch deep at the articulation.
The four cervical vertebræ are each 11/2inch long.
The sternum measures 11/2inch over the facets for the coracoids.
The humerus is 21/16inches over the proximal end, the radial crest not being preserved.
The coracoid is 11/4inch over the proximal end.
The scapula is about 31/2inches long.
The proximal carpal (imperfect) is 15/8inch wide.
The distal carpal is 11/2inch wide.
The lateral carpal is 11/4inch long.
The wing-metacarpal is 11/4inch wide at the proximal end, and7/8inch wide at the distal end.
The proximal end of the first phalange is about 15/8inch wide.
The proximal end of the second phalange is less than an inch wide.
The claw-phalange (imperfect) is about 11/4inch long.
The femur is 4 inches long.
Putting the animal together, the bones give this size :
With the hypothetical parts, this would give a length of about 3 ft. 6 in. from the tip of the snout to the tip of the tail. Then
Which, if the fore-limbs were kept together as in ordinary quadrupeds, would give a height to the body of about 2 ft. 6 in., but as the limbs probably spread in walking as among the bats, the hind-limb would give a better idea of the height of the animal.
Which would give a height of about 13 inches; and, standing in the position of a bird, the height to the crown of the head would be about 2 feet. The majority of the Ornithosaurians of the Cambridge Greensand are of this size.
The spread of the wings, if there were 4 phalanges, would be
Giving a total expanse of about 13 feet. But, from the indications of the wing-finger, I should incline to think an expanse of 10 feet a truer estimate. The largest species attained to twice this size, and the smallest was a fourth as large. Another memoir will present descriptions and restorations of the Greensand species.
Habits.
The varying organization of different Ornithosaurians probably depends on the different habits of the tribes. That they could all fly is probable from the enormous radial crest to the humerus and the great development of the wing-bones, to which a wing-membrane was stretched, comparable to that of a Bat in texture, but more comparable to a Bird in its extent. The groups with long hind-legs probably had the membrane limited to the bones of the arm, while in the species with small hind-legs it may have attained even as great a development as in Bats, though there is no reasonfor suspecting that it extended to the tail. A Pterodactyle cannot be supposed to have hung itself up by the hind-legs as does a Bat, because the hind-claws appear invariably to be directed forward. A Bat walks upon four legs with considerable elegance and speed; the wing is folded in, close to the side, so as to be scarcely noticed; and the outer claw is free to climb with. There can be little doubt but that Pterodactyles walked in a similar way. The thickened mammilate knob at the proximal end of the first phalange is well calculated for contact with the ground. And if it were supposed that the large wing-metacarpal bone were only used to support the wing, and the small metacarpals only used to support the claws by which the creature has sometimes been pictured suspending itself, it would be difficult to believe that the forces of pressure and tension in flying so exactly corresponded to the forces manifested in suspension as to cause the large and the small metacarpals invariably to attain the same length. A correspondence of this kind may be presumed to indicate a correspondence in function; and since the animal did not fly by means of its claws, the inference is that it walked by means of the metacarpal bones. In no other way could the bones have been used equally. The avian ilium would suggest a probability that they also at times stood erect like birds, from which position they could with more ease expand their wings; nor is such an idea opposed by the resemblance of some bones of the hind-limb to what obtains in birds, and of the neck of the femur to what is seen in mammals of great power in the hind-legs.
That they lived exclusively upon land and in air is improbable, considering the circumstances under which their remains are found. It is likely that they haunted the sea-shores, and, while sometimes rowing themselves over the water with their powerful wings, used the wing-membrane as does the Bat to enclose their prey and bring it to the mouth. But the superior development of the pneumatic foramina suggest that their activity was greater than in ordinary sea-birds.
The large Cambridge Pterodactyles probably pursued a more substantial prey than dragon-flies. Their teeth are well suited for fish, but probably fowl and small mammal, and even fruits, made a variety in their food. As the lord of the cliff, it may be presumed to have taken toll of all animals that could be conqueredwith tooth and nail. From its brain it might be regarded as an intelligent animal. The jaws present indications of having been sheathed with a horny covering, and some of the species show a rugose anterior termination of the snout suggestive of fleshy lips like those of the Bat, and which may have been similarly used to stretch and clean the wing-membrane.
The high temperature, coupled with the sub-aerial life, are opposed to the idea of the animal having been naked. The undisturbed condition of the skeleton and some points of structure are opposed to the idea of their having had large feathers. The absence of such remains does not favour the hypothesis of their having been covered with scales, though in the legs of birds a scaly covering is met with. I should anticipate for them a filamentous downy feather, or hair, like a Bat's. The Bat combs its hair with its claws, and the Ornithosaurians may have used their claws in a similar way.
They cannot be supposed to have been gregarious, from the large number of species relatively to specimens. The reproduction may have been much the same as in birds; and the young were probably reared with affectionate care[X].