Pterodactyl

“ One of these sketches shows us such a creature hungrily inspecting a pool where Crinoids, with their long stems, large, closely-coiled Chambered Shells, and Brachiopods, the Oysters and Clams of those days, offer him a tempting repast. Here and there a Pterodactyl, the curious winged reptile of the later middle periods, stretches its long neck from the water, and birds also begin to make their appearance.
After these come the Tertiary periods: the Eocene first, where the landscape is already broken up by hills and mountains, clothed with a varied vegetation of comparatively modern character. ”

“ Some were not larger than a sparrow; others about the size of a woodcock; yet others much larger, the largest of all having a spread of wing (or rather of the flying membranes) of twenty-five feet! It has been concluded that they could perch on trees, hang against perpendicular surfaces, such as the edge of a cliff, stand firmly on the ground, and probably crawl on all fours with wings folded. It may be well at once to point out that the Pterodactyl had no true wings like those of a bird, but a thin membrane similar to that of a bat, only differently supported ”

“ Pterodactyles show singularly little variation in structure in their geological history. We chronicle the loss of the tail and loss of teeth. There is also the loss of the outermost wing digit from the hind foot as a supporter of the wing membrane. But the other variations are in the length of the metacarpus, or of the neck, or head. One of the fundamental laws of life necessitates that when an animal type ceases to adapt its organisation and modify its structures to suit the altered circumstances forced upon it by revolutions of the earth's surface its life's history becomes broken. ”

“ Far the most remarkable of these predecessors of the true birds were the pterodactyls whose bones we still find in our English cliffs at Lyme Regis and Whitby; creatures with a large reptilian head, fierce jaws set with sharp-pointed teeth, and fore-arms prolonged into a great projecting finger so as to support a membranous wing or fold of skin, somewhat analogous to that of the bats. The pterodactyls do not stand anywhere in the regular line of descent toward the true birds ”

“ It would therefore follow—since birds and mammals are warm-blooded—that Pterodactyls were also. Such, at least, is the view of Professor H. G. Seeley, who says of the Cambridge specimens, "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-membranes, as the bat does, to enclose their prey, and bring it to the mouth. ”

“ The forelimbs are always a pair of wings, the fifth digit or “little” finger being enormously elongated for the support of a smooth flying membrane (seen in specimens from the lithographic stone of Bavaria) . The wings are thus constructed on the same plan as those of a bat, but instead of four fingers, only one is elongated to bear the membrane. The hind-limbs are comparatively feeble, and must have been of very little use for walking.
The remains of pterodactyles are found chiefly in marine deposits, so that these reptiles must have frequented the coastlines. ”

“ And a bird's marrow bones are stouter and stronger than those which are filled with air. There are few, if any, bones of Pterodactyles so thick as to suggest the conclusion that they contained marrow, [Pg 135] and the bones of the extremities appear to have been constructed on the lightest type found among terrestrial birds. Their thinness, except in a few specimens from the Wealden rocks, is marvellous; and all the later Pterodactyles show the arrangement, as in birds, by which air from the lungs is conveyed to the principal bones. ”

“ It is scarcely possible to distinguish the remains of the toothed and toothless skeletons except in the dentary character of the jaws. There is no evidence that the toothless types ever possessed a tooth of any sort. They were first found in fragments in England in the Cambridge Greensand, but were afterwards met with in great abundance in the Chalk of Kansas, where the same animals were named Pteranodon. A jaw so entirely bird-like suggests that the digestive organs of Pterodactyles may in such toothless forms at least have been characterised by a gizzard, which is so distinctive of Birds. ”

“ But no Pterodactyle has the head of the humerus convex from the radial to the ulnar sides, and the bird is distinctive in having the ulnar crest developed on the inferior side of the head: a faint approximation to a similar development is seen in Crocodile, but there is no trace of such a process in Pterodactyle. The distal end is more Bird-like than Lacertian in form, but is twisted to a greater angle with the proximal end than in birds.
Altogether the bone is distinctive. The points in which it is unlike birds and reptiles are those in which Birds and Lizards resemble each other ”

“ Closely connected with an animal's habits is the protection to the body which is afforded by the skin. In Pterodactyles the evidence of the condition of the skin is scanty, and mostly negative. Sometimes the dense, smooth texture of the jaw bones indicates a covering like the skin of a Lizard or the hinder part of the jaw of a Bird. Some jaws from the Cambridge Greensand have the bone channeled over its surface by minute blood vessels which have impressed themselves into the bone more easily than into its covering. ”

“ For I imagine, if it can be determined what the nervous and respiratory and circulatory structures of the Pterodactyle were, it becomes a secondary matter to know whether the phalanges are like a lizard's, or the pelvis like that of a mammal. If the animal is asserted to be a mammal, a reptile, or a bird, we ought to be able to adduce evidence that it had the soft parts which are deemed distinctive of the selected class. ”

“ As the bones in the wing of the Pterodactyle thus agree in number and proportion with those in the fore foot of the Lizard, so do they differ entirely from the arrangement of the bones which form the expansors of the wing of the Bat. [63]
The total number of toes in the Pterodactyles is usually four; the exterior, or little toe, being deficient; if we compare the number and proportion of the joints in these four toes with those of Lizards, (Pl. 22, F, G, H, I,) we find the agreement as to number, to be not less perfect than it is in the fingers ”

“ 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 [Pg 31] than his predecessors, saw in the fossil animal a saurian in transition to a bird. ”

“ Cast of brain-cavity.
They are exhibited in Compartments a, b, c of the Table-case of Cabinet J. The letter F in a circle is placed against figured specimens.
History.
The Cambridge Pterodactyles first attain prominence in scientific literature in the year 1859. Professor Owen had figured (plate 32, fig. 6-8) fragments of bones in the Palæontographical Society's Monograph for 1851; the distal end of a large ulna (fig. 6) ; the shaft of a phalange of the wing-finger, probably the first (fig. 7) ; and the upper portion of the shaft of a small humerus showing part of the radial crest (fig. 8) . ”

“ The large Cambridge Pterodactyls probably pursued a more substantial prey than dragon-flies. Their teeth are well suited for fish, but probably fowl and small mammals, and even fruits, made a variety in their food. As lord of the cliff, it may be presumed to have taken toll of all animals that could be conquered with tooth and nail. From its brain it might be regarded as an intelligent animal. ”

“ The waters swarmed with swimming reptiles of unfamiliar shapes and great size, while over its surface hovered and soared innumerable pterodactyls searching for their prey in the waters beneath. The delicate bones of the pterodactyls, beneath the pressure of the superincumbent rocks, have been, almost invariably, crushed flat, requiring skill and care in their excavation. Sometimes, though rarely, has a skeleton been found nearly complete; more frequently are the scattered bones found here and there. ”

“ They are here seen to be well adapted for such a purpose. The upper leg bone is 31⁄4 inches long, the lower leg bone is 41⁄2 inches long, and the singularly strong instep bones are firmly packed together side by side as in a leaping or jumping Mammal, and measure 11⁄2 inches in length. Dimorphodon differs from several other Pterodactyles in having the hind limb provided with a fifth outermost short instep bone, to which two toe bones are attached. These bones are elongated in a way that may be compared, on a small scale, with the elongation of the wing finger in the fore limb. ”

“ The neck is occasionally preserved in a curve like a capital S, as though about to be darted forward like that of a bird in the act of striking its prey. The genera of Pterodactyles with short necks may have had as great mobility of neck as is found among birds named Ducks and Divers; but those Pterodactyles with stout necks, such as Dimorphodon and Ornithocheirus, in which the vertebræ are large, appear to [Pg 84] have been built more for strength than activity, and the neck bones have been chiefly concerned in the muscular effort to use the fighting power of the jaws in the best way. ”

“ B. Suborder Pterodactyloidea
Wing metacarpal, longer or but little shorter than forearm. Tail very short. No cervical ribs. Fifth toe more or less reduced.
Family Pterodactylidae. Nares and antorbital vacuity more or less coalescent. Teeth in anterior part of jaws. Anterior dorsal vertebrae not fused. All metacarpals articulating with carpus. Prepubes not band-like. Smaller.
Upper Jurassic. Pterodactylus Cuvier (Ornithocephalus Sommering, Diopecephalus Seeley, Cycnorhamphus Seeley, Pterodracon Lydekker) , Europe.
Family Ornithocheiridae. Skull more elongate. A supraoccipital crest. ”

“ Most anatomists will probably agreee in considering that many features of the skeleton of pterodactyls, such for example as its remarkable pneumaticity are due to modifications for flight, but the author considers that Pterodactyls and Birds form two parallel groups which may be regarded as ancient divergent forks of the same branch of animal life. But whether we accept all Professor Seeley's deductions or not we may safely accept his facts and we are indebted to him for having placed so much information within our reach and for having given it in so readable a form. ”

“ In Pterodactylus dubius and P. grandipelvis and P. Kochi there are 5 or 6 vertebræ in the sacrum. In birds the sacral vertebræ vary from 5 to 22; in bats the number is from 5 to 6.
The short tails of Pterodactyles are more like those of mammals than birds; they include from 10 to 15 tail-vertebræ. In birds there are from 6 to 10 tail-vertebræ. Rhamphorhynchus has 38-40 tail-vertebræ, secured between thread-bones like those in the tail of rats.
The dorsal ribs are reptile-like. In herbivorous mammals and birds they are broader. A few species have the first pair of ribs large. ”

“ As stated by me in the American Naturalist (l. c.) , the type specimen of Pteranodon, also collected by myself, was incomplete, and the figures of it, as given by Marsh, are faulty.
The elements of the skull are all so firmly united that they can not be distinguished. There are no indications whatever of a horny sheath enclosing the jaw, and it is improbable that the covering of these parts was essentially different from that in the slender jawed Pterodactylidae. In texture, the maxillaries are fine-grained, and wholly without the vascular foramina found in the corresponding bones of birds. ”

“ In the extinct pterodactyles—which were truly flying reptiles—we meet with an approximation to the structure of the bat, but in the pterodactyle we have only one finger elongated in each hand: a striking example of how the very same function may be provided for by a modification similar in principle, yet surely manifesting the independence of its origin. When we go to lower animals, we find flight produced by organs, as the wings of insects, which are not even modified limbs at all ”

“ Von Meyer noticed the resemblance of this anterior process to the interclavicle of the Croco [Pg 109] dile in position; but it is more like the keel of a bird's sternum, and is not a separate bone as in Reptiles. In Pterodactyles from the Cretaceous rocks, the side bones, called coracoids, are articulated to saddle-shaped surfaces at the hinder part of the base of this keel, which are parallel in Ornithocheirus, as in most birds, but overlap in Ornithodesmus, as in Herons and wading birds. ”

“ Yet the kind of heart which is always associated with vital structures such as Pterodactyles are inferred to have possessed from the brain mould and the pneumatic foramina in the bones, is the four-chambered heart of the bird and the mammal. Considering these organs alone—of which the fossil bones yield evidence—we might anticipate, by the law of known association of structures, that nothing distinctly reptilian existed in the other soft part of the vital organisation, because there is no evidence in favour of or against such a possibility. ”

“ 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 11⁄2 inches to its back standing on all fours, and but little over 21⁄2 inches standing as a biped, on the hind limbs. ”