 CHAPTER XI. SHOLDER GURTLE AND FORLAM. STIRNAM. The sternum is always a distinguishing part of the bony structure of the breast. In crocodiles it is a cartilage to which the sternal ribs unite, and upon its front portion a flat knife-like bone called the interclavicle is placed. In lizards like the chameleon it is a lozenge-shaped structure of thin bony texture also bearing a long interclavicle, which supports the clavicular bones, named collar bones in man, which extend outward to the shoulder blades. Among mammals the sternum is usually narrow and flat and often consists of many successive pieces in the middle line, on the underside of the body. Among bats the anterior part is somewhat widened from side to side to give attachment to the collar bones, but the sternum still remains a narrow bone much narrower than in dolphins and not differing in character from many other mammals, notwithstanding the bat's power of flight. The bone develops a median keel for the attachment of the muscles of the breast, but something similar is seen in burrowing insectivorous mammals like the moles. So that as von Meyer remarked the presence of a keel on the sternum is not in itself sufficient evidence to prove flight. Among birds the sternum is greatly developed. Broad and short in the ostrich tribe it is devoid of a keel, and therefore the keel, if present in a bird, is suggestive of flight. The keel is differently developed according to the mode of attachment of the several pectoral muscles which cover a bird's breast. In several water birds the keel is strongly developed in front and dies away towards the hinder part of the sternum, as in the cormorant and its allies. The sternum in German pterodactyls is most nearly comparable to these birds. In the solenhofen slate the sternum is fairly well preserved in many ornithosaurs. It is relatively shorter than in birds, and is broader than long, but not very like the sternum of reptile or mammal in form. The keel is limited to the anterior part of the shield of the sternum, as in merganser and the cormorant, and is prolonged forward for some distance in advance of it. Von Meyer noticed the resemblance of this anterior process to the interclavicle of the crocodile in position, but it is more like the keel of a bird's sternum, and is not a separate bone, as in reptiles. In pterodactyls 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 ornithochiris, as in most birds, but overlap in ornithodesmus, as in herons and wading birds. The keel was pneumatic, and when broken is seen to be hollow, and appears to have been exceptionally high in ramphorincus, a genus in which the wing bones are greatly elongated. Von Meyer found in ramphorincus on each side of the sternum a separate lateral plate with six pairs of sternal ribs, which unite the sternum with the dorsal ribs, as in the young of some birds. The hinder surface of the sternum is imperfectly preserved in the toothless pterodactyls of Kansas. Professor Williston states that the bone is extremely thin and pentagonal in outline, projecting in front of the coracoids in a stout, blunt, keel-like process, similar to that seen in the pterodactyls of the Cambridge greensand. American specimens have not the same notch behind the articulation for the coracoid to separate it from the transverse lateral expansion of the sternal shield. The lateral margin in the Cambridge greensand specimens, figured by Professor Owen and myself, is broken. But Professor Williston had the good fortune to find on the margin of the sternum the articular surfaces which gave attachment to the sternal ribs. The margin of the sternal bone thickens at these facets, four of which are preserved. The sternum in ornithostoma was about four and a half inches long by less than five and a half inches wide. The median keel extends forward for rather less than two inches, while in the smaller Cambridge species of ornithochiris it extends forward for less than an inch and a half. A sternum of this kind is unlike that of any other animal, but has most in common with a bird, and may be regarded as indicating considerable power of flight. The bone cannot be entirely attributed to the effect of flight, since there is no such expanded sternal shield in bats. The small number of sternal ribs is even more characteristic of birds than mammals or reptiles. The shoulder girdle. The bones which support the forelimb are one of the distinctive regions of the skeleton defining the animal's place in nature. Among most of the lower vertebrata, such as amphibians and reptiles, the girdle is a double arch, the arch of the collarbone or clavicles in front, and the arch of the shoulder blade or scapula behind. The clavicular arch, when it exists, is formed of three or five parts, a medium bar named the interclavicle, external to which is a pair of bones called clavicles, reaching to the front of the scapulae when they are present. And occasionally there is a second pair of bones called supraclavicles, extending from the clavicles up the front margins of the scapulae. Thus the clavicular arch is placed in front of the scapular arch. The supraclavicles are absent from all living reptiles, and the clavicles are absent are absent from crocodiles. The interclavicle is absent from all mammals except echidna and ornitho rancus. Clavicles also may be absent in some orders of mammals. Hence the clavicular arch may be lost, though the collar bones are retained in man. The scapular arch also is more complicated and more important in the lower than in the higher vertebrata. It may include three bones on each side named coracoid, precoracoid, and scapula. But in most vertebrates the coracoid and precoracoid appear never to have been segmented so as to be separated from each other. And it is only among extinct types of reptiles which appear to approximate to the monotreme mammals that separate precoracoid bones are found. Though among most mammals, probably, there are stages of early development in which precoracoids are represented by small cartlages. Though few mammals except Edintara, like the sloths and anteaters, retain even the coracoids as distinct bones. Therefore, accepting the Edintara and the monotremes, the distinctive feature of the mammalian shoulder girdle appears to be that the limbs are supported by the shoulder blades, termed the scapulae. Among reptiles there are several distinct types of shoulder girdle. Colonians possess a pair of bones termed coracoids which have no connection with a sternum. And their scapulae are formed of two widely divergent bars divided by a deeper notch than is found in any fossil reptiles. Among lizards, both scapula and coracoid are widely expanded and the coracoid is always attached to the sternum. Chameleons have the blade of the scapula long and slender, but the coracoid is always as broad as it is long. Crocodiles have the bone more elongated so that it has somewhat the aspect of a very strong first sternal rib when seen on the ventral face of the animal. The bone is perforated by a foramen, which would probably lie in the line of separation from the precoracoid if any such separation had ever taken place. The scapula, or shoulder blade, of crocodiles is a similar flat bone, very much shorter than the scapula of a chameleon, and more like that of the New Zealand Hatteria. Thus there is very little in common between the several reptilian types of shoulder girdle. In birds the apparatus for the support of the wings has a far-off resemblance to the crocodilian type. The coracoid bones, instead of being directed laterally outward and upward from the sternum, as among crocodiles, are directed forward so as to prolong the line of the breastbone, named the sternum. The bird's coracoid is sometimes flattened towards the breastbone among swans and other birds. Yet as a rule the coracoid is a slender bar, which combines with the still more slender and delicate blade of the scapula, which rests on the ribs to make the articulation for the upper arm bone. Among reptiles the scapula and coracoid are more or less in the same straight line as in the ostrich, but in birds of flight they meet at an angle which is less than a right angle, and where they come in contact the external surface is thickened and excavated to make the articulation for the head of the humerus. There is nothing like this shoulder girdle outside the class of birds until it is compared with the corresponding structure in these extinct animals called pterodactyls. The resemblance between the two is surprising. It is not merely the identity of form in the coracoid bone and the scapula, but the similar angle at which they meet, and the similar position of the articulation for the humerus. Everything in the pterodactyls shoulder girdle is bird-like except the absence of the representative of the clavicles, that forked V-shaped bone of the bird, which in scientific language is known as the furculum, and is popularly termed the merri-thought. This kind of shoulder girdle is found in the genera from the lyus and the olytic rocks, both of this country and Germany. In the cretaceous rocks the scapula presents in most cases a different appearance. The coracoid is an elongated, somewhat triangular bone, compressed on the outer margin as in birds, but differing alike from birds and other pterodactyls in not being prolonged forward beyond the articulation for the humerus. In these cretaceous genera, toothed and toothless alike, the articulation for the upper arm bone truncates the extremity of the coracoid so that the bone is less like that of a bird in this feature. Perhaps it shows a modification towards the crocodilian direction. The scapula, which unites with the coracoid at about a right angle, is similarly truncated by the articular surface for the humerus. But the bone is somewhat expanded immediately beyond the articulation and compressed. And instead of being directed backward, it is directed inward over the ribs to articulate with the neural arches of the early dorsal vertebrae in the genera found in strata associated with the chalk. As the bone approaches this articulation, it thickens and widens a little, becoming suddenly truncated by an ovate facet, which exactly corresponds to the transversely ovate impression, concave from front to back, which is seen in the neural arches of the dorsal vertebrae on which it fits. This condition is not present in all cretaceous pterodactyls. It does not occur in the Kansas fossil, named by Professor Marsh Nicodactylus. And it appears to be absent from the pterodactyls of the English willed, named Ornithodesmus. There is no approach to this transverse position of the scapulae among birds. And while the form of the bones in the older genera of Ornithosaurs is singularly bird-like, the angular arrangement in this cretaceous genus is obtained by closely approximating the articulations on the sternum so that the coracoids extend outward, as in reptiles, instead of forward, as in birds. And the extremities of the scapulae similarly approximate towards each other. This rather recalls the relative positions of scapula and coracoid among crocodiles. If crocodile and bird had been primitive types of animals, instead of surviving types, it might almost seem as though there had been a cunning and harmonious blending of one with the other in evolving this form of shoulder girdle. The forelimb. The bones of the forelimb generally correspond in length with the similar parts of the hindlimb. The upper arm bone corresponds with the upper leg bone, and the forearm bone is as long as the fore leg bone. Then differences begin. The bones which correspond to the back of the hand in man, termed the metacarpus, are variable in length in pterodactyls, sometimes very long and sometimes short. The wing metacarpal bone is always stout, and the others are slender. The extremity of the metacarpus was applied to the ground. Three small digits of the hand are developed from the three small metacarpal bones, and terminate in large claws. The great wing finger was bent backward, and only touched the ground where it fitted upon the wing metacarpal bone. It appears sometimes to have been as long as the entire vertebral column. Owing to the circumstance that the joint in the arm in pterodactyls was not at the wrist as among birds, but between the metacarpus and the phalanges, it follows that the forelimb was longer than the hindlimb when the metacarpus was long. But the difference would not interfere with the movements of the animal, either upon four feet or on two feet, for in bats and birds the disproportion and length is greater. Humorous or upper arm bone The first bone in the forearm, the humerus, is remarkable chiefly for the compressed crescent form of its upper articular end, which is never rounded like the head of the upper arm bone in man, and secondly for the great development of the external process of bone near that end termed the radial crest. Sir Richard Owen compared the bone to the humerus of both birds and crocodiles, but in its upper articular end the crocodile bone may be said to be more like a bird than it is like the pterodactyl. In flying reptiles the articular surface next to the shoulder girdle is somewhat saddle shaped, being concave from side to side above and convex vertically, while most animals with which it can be compared have the articular head of the bone convex in both directions. A remarkable exception to this general rule is found in some fossil animals from South Africa, which from resemblance to mammals in their teeth have been termed theriadonts. They sometimes have the head of the bone concave from side to side and convex in the vertical direction. To this condition ornithorhynchus makes a slight approximation. The singular expansion of the structure called the radial crest finds no close parallel in reptiles, though crocodiles have a moderate crest on the humerus in the same position. And in theriadonts the radial crest extends much further down the shaft of the humerus. No bird has a radial crest of a similar kind, though it is prolonged some way down the shaft in archaeopteryx. In therodactyls it sometimes terminates outward in a smooth rounded surface, which might have been articular if any structure could have articulated with it. There is also a moderate expansion of the bone on the ulnar side in some therodactyls, so that the proximal end often encloses nearly three fourths of an ovate outline. The termination of the radial crest is at the opposite end of this oval to the wider articular part of the head of the bone in some specimens from the Cambridge green sand. The radial crest is more extended in ramphorynchus. All specimens of the humerus show a twist in the length of the bone, so that the end towards the forearm, which is wider than the shaft, makes a right angle with the radial crest on the proximal end, which is not seen in birds. The shaft of the humerus is always stouter than that of the femur, though different genera differ in this respect. The humerus in genera from rocks associated with the chalk presents two modifications chiefly seen in the characters of the distal end of the bone. One of these is a stout bone with a curiously truncated end where it joins the two bones of the forearm, and the other is more or less remarkable for the rounded form of the distal condyles. Both types show distinct articular surfaces. The inner one is somewhat oblique and concave, the outer one rounded, the two being separated by a concave channel so that the ulna makes an oblique articulation with the bone as in birds, and the radius articulates by a more or less truncated or concave surface. Ulna and radius. The bones of the forearm are similar to each other in size, and if there be any difference between them, the ulna is slightly the larger. There is some evidence that in rampharencus the upper end of the ulna was placed behind the radius, probably in consequence of the mode of attachment of those bones to the humerus. The ulna abutted towards the inner and lower border, while the radius was towards the upper border, consequent upon the twist in the humerus. This condition corresponds substantially with the arrangement in birds, but differs from birds in the relatively more important part taken by the radius in making the articulation. The bones are compared in dimorphodon with the golden eagle drawn of the same size. In birds the ulna supports the great feathers of the wing, and this may account for the size of the bone. The ulna is best seen at its proximal end in the specimens from the Cambridge green sand, where there is a terminal alecranon ossification forming an oblique articulation which frequently comes away and is lost. It is sometimes well preserved and indicated by a suture. The examples of ulna from the lyus show a slight expansion of the bone at both ends, and at the distal end toward the wrist the articulation is well defined where the bone joins the carpus. The larger specimens of the bone are broken. The distal articular surface is only connected with the proximal end of the bone in small specimens. It always shows on the one margin a concavity followed by a prominent boss, and an oblique articulation beyond the boss. On the side towards the radius, on the lower end of the shaft, there is an angular ridge which marks the line along which the ulna overlaps the radius. The lower end of the radius has a simple, slightly convex articulation somewhat bean shaped. No rotation of these bones on each other was possible as in man. There is a third bone in the forearm. This bone, named the pteroid, is commonly seen in skeletons from Solenhofen. It was regarded by von Meyer as having supported the wing membrane in flight. Some writers have interpreted it as an essential part of the pterodactyl skeleton, and von Meyer thought that it might possibly indicate a fifth digit in the hand. The only existing structure at all like it is seen in the South African insectivorous mammal, named chrysochlorous copensis, the golden mole, which also has three bones in the forearm, the third bone extending halfway up towards the humerus. In that animal, the third bone appears to be behind the others and adjacent to the ulna. In the German fossils, the pteroid articulated with a separate carpal or metacarpal bone placed on the side of the arm adjacent to the radius, and the radius is always more inward than the ulna. If the view suggested by von Meyer is adopted, this bone would be a first digit extending outward and backward towards the humerus. That view was adopted by Professor Marsh. It involves the interpretation of what has been termed the lateral carpal as the first metacarpal bone, which would be as short as that of a bird, but turned in the opposite direction backward. The first digit would then only carry one phalange, and would not terminate in a claw, but lie in the line of the tendon which supports the anterior wing membrane of a bird. The third bone in the forearm of chrysochlorous does not appear to correspond to a digit. The bone is on the opposite side of the arm to the similar bone of a pterodactyl, and therefore cannot be the same structure in the golden mole. The interpretation which makes the pteroid bone in the first digit has the merit of accounting for the fifth digit of the hand. All the structures of the hand are consistent with this view. The circumstance that the bone is rarely found in contact with the radius, but diverging from it, shows that it plays the same part in stretching the membrane in advance of the arm that the fifth digit holds in supporting the larger wing membrane behind the arm. According to Professor Williston, the American toothless pterodactyl, or nithostoma, has but a single phalange on the corresponding first toe of the hind foot, and that bone he describes as long, cylindrical, gently curved, and bluntly pointed. There is some support for this interpretation, but I have not seen any English or German pterodactyls with only one phalange in the first toe. The wing in pterodactyls would thus be stretched between two fingers which are bent backward, the three intermediate digits terminating in claws. The carpus. The wrist bones in the reptilia usually consist of two rows. In crocodiles, in the upper row there is a large inner and a small outer bone, behind which is a lunate bone, the remainder of the carpus being cartilaginous. Only one carpal is converted into bone in the lower row. It is placed immediately under the smaller upper carpal. In colonians, the turtle and tortoise group, the characters of the carpus vary with the family. In the upper row there are usually two short carpals which may be blended under the ulna, while the two under the radius are commonly united. The lower row is made up of several small bones. Lizards, too, usually have three bones in the proximal row and five smaller bones in the distal row. The correspondence of the distal carpals with the several metacarpal bones of the middle hand is a well-known feature of the structure of the wrist. Von Meyer remarks that the carpus is made up of two rows of small bones in the solenhofen pterodactyls, while in birds there is one row consisting of two bones. The structure of the carpus is not distinct in all German specimens. But in the short-tailed solenhofen genera, the bones in the two rows retain their individuality. In all the cretaceous genera, the carpal bones of each row are blended into a single bone so that two bones are superimposed, which may be termed the proximal and distal carpals. One specimen shows by an indication of sutures the original division of the distal carpal into three bones, and the separated constituent bones are very rarely met with. Two bones of the three confluent elements contribute to the support of the wing metacarpal, and the third gives an articular attachment to the bone which extends laterally at the inner side of the carpus, which I now think may be the first metacarpal bone turned backward towards the humerus. The three component bones meet in the circular pneumatic foramen in the middle of the underside of the distal carpal. There is no indication of division of the proximal carpal in these genera into constituent bones. This condition is somewhat different from birds. In 1873 Dr. Rosenberg of Dorpat showed that there is in the bird a proximal carpal formed of two elements, and a distal carpal also formed of two elements. Therefore the two constituents of the distal carpal in the bird, which blends in the mature animal with the metacarpus, forming the rounded pulley joint, may correspond with two of the three bones in the cretaceous pterodactyl or nithochiris. The width of a proximal carpal rarely exceeds two inches, and that of a distal carpal is about an inch and three quarters. Two such bones, when in contact, would not measure more than one inch in depth. The lower surface shows that the wing had some rotary movement upon the carpus outward and backward. Metacarpus The metacarpus consists of bones which correspond to the back of the hand. The first digit of the hand in clawed animals has the metacarpal bone short or shorter than the others. Among mammals, metacarpal bones are sometimes greatly elongated, and a similar condition is found in pterodactyls, in which the metacarpal bone may be much longer than the phalange which is attached to it. Two metacarpal bones appear to be singularly stouter than the others. The first bone of the first digit, if rightly determined, is much shorter than the others, and is, in fact, no longer than the carpus. It is a flat oblong bone attached to the inner side of the lower carpal, and instead of being prolonged distally in the same direction as the other metacarpal bones, is turned round and directed upward so that its upper edge is flush with the base of the radius and gives attachment to a bone which resembles a terminal phalange of the wing finger. According to this interpretation, it is the first and only phalange in the first digit. The bone is often about half as long as the forearm terminates upward in a point, is sometimes curved, and frequently diverges outward from the bones of the forearm, as preserved in the associated skeleton, being stretched towards the radial crest of the humerus. This mode of attachment of the supposed first metacarpal, which is true for all Cretaceous pterodactyls, has not been shown to be the same for all those from the Solenhofen slate. There is no greater anomaly in this metacarpal and phalange on the inner side being bent backward than there is in the wing finger being bent backward on the outer side. The three slender intervening digits extend forward between them as though they were applied to the ground for walking. The bone which is usually known as the wing metacarpal is frequently stouter at the proximal end, towards the carpus than towards the phalange. At the carpal end it is oblong and truncated, with a short middle process, which may have extended into the pit in the base of the carpal bone, while the distal terminal end is rounded exactly like a pulley. There is great difference in the length of the metacarpus. In the American genus Ornithostoma it is much longer than the forearm. In Ramphorencus it is remarkably short, though perhaps scarcely so short as in dimorphodon or in scaphonathis. The largest Cretaceous examples are about two inches wide where they join the carpus. The bone is sometimes a little curved. Between the first and fifth or wing metacarpal are the three slender metacarpal bones which give attachment to the clawed digits. They bear much the same relation to the wing metacarpal that the large metatarsal of a kangaroo has to the slender bones of the instep which are parallel to it. The facet for the wing metacarpal on the carpus is clearly recognized, but as a rule there is no surface with which the small metacarpals can be separately articulated. One or two exceptional specimens from the Cambridge Greensand appear to have not only surfaces for the wing metacarpal, but two much smaller articular surfaces giving attachment to smaller metacarpals. While in one case there appears to be only one of these additional impressions, it is certain that all the animals from the Lius and Oolites have three clawed digits, but at present I have seen no evidence that there were three in the Cretaceous genera, though Professor Williston's statements and restoration appear to show that the toothless pterodactyls have three. Another difference from the Oolitic types, according to Professor Williston, is in the length of the slender metacarpals of the clawed phalanges being about one third that of the wing metacarpal, but this is probably due to imperfect ossification at the proximal end. For at the distal end the bones all terminated on the same level, showing that the four outer digits were applied to the ground to support the weight of the body. The corresponding bone in the horse and oxen is carried erect, so as to be in a vertical line with the bones of the forearm. And the same position prevails usually, though not invariably, with the corresponding bone in the hind limb, while in many clawed animals the metacarpus and metatarsis are both applied upon the ground. In pterodactyls the metatarsal bones are preserved in the rock in the same straight line with the smaller bones of the foot, or make an angle with a shin bone, leading to the conviction that the bones of the foot were applied to the ground as in man, and sometimes as in the dog, and were thus modified for leaping. Just as the human metacarpus is extended in the same line with the bones of the forearm, and the movement of jointing occurs where the fingers join the metacarpus, so pterodactyls also had these bones differently modified in the fore and hind limbs for the functions of life. The result is to lengthen the fore limb as compared with the hind limb, by introducing into it an elevation above the ground which corresponds to the length of the metacarpus, always supposing that the animal commonly assumed the position of a quadruped when upon the earth's surface. This position of the metacarpus is a remarkable difference from birds, because when the bird's wing is at rest it is folded into three portions. The upper arm bone extends backward, the bones of the forearm are bent upon it so as to extend forward, and then at the wrist the third portion which includes the metacarpus and finger bones is bent backward, so that the metacarpus in the pterodactyl differs from birds in being in the same line as the bones of the forearm, whereas in birds it is in the same line with the digit bones of the hand. It is worthy of remark that in bats which are so suggestive of pterodactyls in some features of the hand the metacarpals and phalanges are in the same straight line, so that in this respect the bat is more like the bird. But pterodactyls in the relation of these bones to flight are quite unlike any other animal and have nothing in common with the existing animals named reptiles. The hand. From what has just been said it follows that the construction of the hand is unique. It may be contrasted with the foot of a bird. The bone which is called in the language of anatomists the tarsometatarsis and is usually free from feathers and covered with skin is commonly carried erect in birds so that the whole body is supported upon it and from it the toes diverge outward. It is formed in birds of three separate bones blended together. In the forelimb of the pterodactyl the metacarpus has the same relation to the bones of the forearm that the metatarsis has to the corresponding bones of the leg in a bird. But the three metacarpal bones in the pterodactyl remain distinct from each other perhaps because the main work of that region of the skeleton has devolved upon the digit called the wing finger which is not recognized in the bird. In the pterodactyls from the solenhofen slate there is a progressive number of phalanges in the three small digits of the hand which were applied to the ground. This number in the great majority of species follows the formula of two bones in the first, three bones in second, and four in the third. So that in the innermost of the claw digits only one bone intervenes between the metacarpal and the claw. The fingers slightly increase in length with increase in number of bones which form them. The terminal claw bones are unlike the claws of birds or reptiles. They are compressed from side to side and extremely deep and strong with evidence of powerful attachment for ligaments so that they rather resemble in their form and large size the claws of some of the carnivorous fossil reptiles often grouped as dinosauria such as have been termed aristosuchus and megalosaurus. In the hand of the ostrich the first and second digits terminate in claws while the third is without a claw. But these claws of the ostrich and other birds are slender, curved, and rather feeble organs. In the archaeopteryx a fossil bird which agrees with the pterodactyls in retaining the separate condition of the metacarpal bones and in having the same number of phalanges in two of the fingers of the forelimb the terminal claws are rather more compressed from side to side and stronger than in the ostrich but not nearly so strong as in the pterodactyl. The archaeopteryx differs from the pterodactyl in having no trace of a wing finger. The first metacarpal bone is short as in all birds and the first phalange scarcely lengthens that segment of the first digit of the bird's hand to the same length as the other metacarpal bones. It therefore was not bent backward like the first digit in pterodactyls. The wing finger from which the genius of Cuvier selected the scientific name pterodactyl for these fossils yields their most distinctive character. It is a feature which could only be partly paralleled in the bat by making changes of structure which would remove every support to the wing but the outermost digit of that animal's hand. In the bat's hand the membrane for flight is extended chiefly by four diverging metacarpal bones. There are only two or three phalanges in each digit in its four wing fingers. In pterodactyls the metacarpal bones are, as we have seen, arranged in close contact and take no part in stretching the wing. The wing finger In birds there is nothing whatever to represent the wing finger of the pterodactyl for it is an organ external to the finger bones of the bird and contains four phalanges. The first phalange is quite different from the others. Its length is astonishing when compared with the small phalanges of the clawed fingers. The articular surface which joins on to the wing metacarpal bone is a concave articulation which fits the pulley in which that bone ends. The pulley articulation admits of an extension movement in one direction only. Many specimens show the wing finger to be folded up so as to extend backward. The whole finger is preserved in other specimens straightened out so as to be in line with the metacarpus. This condition is well seen in Professor Marsh's specimen of Ramphorincus which has the wing membrane preserved in which all bones of the forearm metacarpus and wing finger are extended in a continuous curve. The outer surface of the end of the first bone of the wing finger overlaps the wing metacarpal so that a maximum of strength and resistance is provided in the bony structures by which the wing is supported. There is therefore in flight only one angular bend in the limb and that is between the upper arm bone and the forearm. An immense pneumatic foramen is situate in a groove on the underside of the upper end of the first phalange in ornithocaris but is absent in specimens from the Kimmeridge clay. This bone is long and stout. It terminates at the lower end in an obliquely truncated articular surface. Specimens occur in the Cambridge green sand which are two inches broad at the upper end and nearly one and a half inch wide at the lower end. An imperfect bone from the chalk is fourteen and one half inches long. An imperfect bone from the chalk is fourteen and one half inches long. The bones are all flattened. Specimens from the chalk of Kansas at Munich are 28 inches long. The second phalange is concave at the upper articular end and convex in the longer direction at the lower end. The articular points of union between the several phalanges form prominences on the underside of the finger in consequence of the adjacent bones being a little widened at their junction. It should be mentioned that there is a proximal epiphysis or separate bone to the first phalange adjacent to the pulley joint of the metacarpal bone which is like the separate olecranon process of the ulna of the forearm. It sometimes comes away in specimens from the chalk and Cambridge green sand leaving a large circular pit with a depressed narrow border. On the outer side of this process is a rounded boss which may possibly have supported the bone if it were applied to the ground with the wing folded up like the wing of a bat directed upward and backward at the animal's side. The forebones of the wing finger usually decrease progressively in length so that in ramphorincus in which the length of the animal's head only slightly exceeds three and one half inches the first phalange is nearly as long the second phalange is about three and one fourth inches the third is two and three fourth inches and the fourth a little over two inches thus the entire length of the four phalanges slightly exceeds eleven inches or rather more than three times the length of the head but the forearm and metacarpus in this type only measure three inches therefore the entire spread of wings could not have been more than two feet nine inches the largest ornithosaur in which accurate measurements have been made is the toothless pterodactyl or nithostoma also named pteranodon from north america in that type the head appears to have been about three or four feet long and the wing finger exceeded five feet while the length of the forearm and metacarpus exceeded three feet the width of the body would not have been more than one foot the length of the short humerus which was about 11 inches did not add greatly to the stretch of the wing so that the spread of the wings as stretched in flight may be given as probably not exceeding 17 or 18 feet a fine example of the wing bones of this animal quite as large has been obtained by the british museum natural history many years ago on very fragmentary materials i estimated the wings in the english cretaceous or nithochiris as probably having a stretch of 20 feet in the largest specimens basing the calculation partly upon the extent of the longest wings and existing birds relatively to their bones and partly upon the size of the largest associated bones which were then known end of chapter 11 chapter 12 of dragons of the air by harry sealy this libra vox recording is in the public domain chapter 12 evidences of the animals habits from its remains such are the more remarkable characters of the bones in a type of animal life which was more anomalous than any other which people the earth in the secondary epic of geological time its skeleton in different parts resembles reptiles birds and mammals with modifications and combinations so singular that they might have been deemed impossible if nature's power of varying the skeleton could be limited since ornithosaurus were provided with wings we may believe the animals to some extent to have resembled birds inhabit their modes of progression were more varied for the structures indicate an equal capacity for movement on land as a biped or as a quadruped with movement in the air there is little evidence to support the idea that they were usually aquatic animals the majority of birds which frequent the water have their bodies stored with fat and the bones of their extremities filled with marrow and a bird's marrow bones are stouter and stronger than those which are filled with air there are few if any bones of pterodactyls so thick as to suggest the conclusion that they contained marrow 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 welden rocks is marvelous and all the later pterodactyls show the arrangement as in birds by which air from the lungs is conveyed to the principal bones no pterodactyl has shown any trace of the webfooted conditions seen in birds which swim on the water unless the diverging bones of the hind foot in rampho rancus supports that inference the bones of the hind foot are relatively small and if it were not that a bird stands easily upon one foot might be considered scarcely adequate to support the animal in the position which terrestrial birds usually occupy yet as compared with the length and breadth of the foot in an ostrich the toes of an ornithosaur are seen to be ample for support these facts appear to discourage the idea that the animals were equally at home on land and water and in air some light may be thrown upon the animals habits by the geological circumstances under which the remains are found the pterodactyl named dimorphodon from the lyos of the south of england is associated with evidences of terrestrial land animals the best known of which is scolidosaurus an armored dinosaur adapted by its limbs for progression on land and the pterodactyl campylonathus from the lyos of whitby is associated with trunks of coniferous trees and remains of insects so that the occurrence of pterodactyls in a marine stratum is not inconsistent with their having been transported by streams from off the old land surface of the lyos on which coniferous trees grew and dinosaurs lived similar considerations apply to the occurrence of the ramphosophilus in the stonesfield slate of england the deposit is not only formed in shallow water but contains terrestrial insects a variety of land plants and many reptiles and other animals which lived upon land the specimens from the per beck beds again are in strata which yield a multitude of the spoils of a nearly adjacent land surface while the numerous remains found in the marine solenhofen slate in germany are similarly associated with abundant evidences of varied types of terrestrial life the evidence grows in force from its cumulative character the wielding beds which yield many terrestrial reptiles and so much evidence of terrestrial vegetation and shallow water conditions of disposition have afforded important pterodactyl remains from the isle of white and sussex the chief english deposit in which these fossils are found the upper greensand has afforded thousands of bones battered and broken on a shore where they have lain in little associated groups of remains often becoming overgrown with small marine shells side by side with them are found bones of true terrestrial lizards and crocodiles of the type of the gavel of the indian rivers many terrestrial dinosaurs and other evidences of land life including fossil resins such as are met with in the form of amber or copal at the present day the great bones of pterodactyls found in the chalk of kent near rochester became entombed beyond question far from a land surface there is nothing to show whether the animals died on land and were drifted out to see like the timber which is found waterlogged and sunken after being drilled by the shipworm pterodoh of that epic seeing the power of flight which the animal possessed storms may have struck down travelers from time to time when far from land evidence of habit of another kind may be found in their teeth they are brightly enameled sharp formidable and are frequently long overlapping the sides of the jaws they are organs which are often better adapted for grasping than for tearing as may be seen in the inclined teeth of ramposcephalus of the stonesfield slate and better adapted for killing than tearing from their piercing forms and cutting edges in general like ornithochiris of the green sand the manner in which the teeth were implanted and carried is better paralleled by the fish eating crocodile of indian rivers than by the flesh eating crocodiles or muggers which live indifferently in rivers and the sea as the king fisher finds its food from the surface of the water without being in the common sense of the term a water bird so some pterodactyls may have fed on fish for which their teeth are well adapted both in the stream and by the shore a pterodactyls teeth vary a good deal in appearance the few large teeth in the front of the jaw in dimorphodon associated with the many small vertical teeth placed further backward suggest that the taking of food may have been a process requiring leisure since the hinder teeth adapted to mincing the animals meat are extremely small the way in which the teeth are shaped and arranged differs with the genera in pterodactyls they are short and broad and few placed for the most part towards the front of the jaws their lancet shaped form indicates a shear like action adapted to dividing flesh in the associated genus ramphorincus the teeth are absent from the extremity of the jaw are slender pointed spaced far apart and extend far backward when the jaws of the ramphorincus are brought together there is always a gap between them in front which has led to belief that the teeth were replaced by some kind of horny armature which has perished in the long-nosed english type of ornithochiris the jaws are compressed together so that the teeth of the opposite sides are parallel to each other with the margins well filled with teeth which are never in close contact though occasionally closer and larger in front in some of the forms with thick truncated snouts it is not the least interesting circumstance of the dentition of pterodactyls that associated in the same deposits with these most recent genera with teeth powerfully developed there is a genus named ornithostoma from the resemblance of its mouth to that of a bird in being entirely devoid of teeth 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 green sand but were afterwards met with in great abundance in the chalk of kansas where the same animals were named tyrannodon a jaw so entirely birdlike suggests that the digestive organs of pterodactyls may in such toothless forms at least have been characterized by a gizzard which is so distinctive of birds the absence of teeth in the great anteater and some other allied mammals has transferred the function which teeth usually perform to the stomach one part of which becomes greatly thickened and muscular adapting itself to the work which it has to perform it is probable that the gizzard may be developed in relation to the necessities which food creates since even trout feeding on the shellfish in some irish locks acquire such a thickened muscular stomach and a like modification is recorded in other fishes as produced by food closely connected within animals habits is the protection to the body which is afforded by the skin in pterodactyls 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 thus in the species of ornithoceros distinguished as microdon the palate is absolutely smooth while in the species named mecaro rincus it is marked by parallel impressed vascular grooves which diverge from the median line this condition clearly indicates a difference in the covering of the bone and that in the latter species the covering had fewer blood vessels and more horny protection than in the other the tissue may not have been a firmer consistent than in the palette of mammals the extremity of the beak is often as full of blood vessels as the jaw of a turtle or crocodile covering of the body there is no trace even in specimens from the sullenhofen or stones feel slate of any covering to the body there are no specimens preserved like mummies and although the substance of the wings is found there is no trace of fur or feathers bones or scales on the skin the only example in which there is even an appearance suggesting feathers is in the beautiful scapho nathus at bond and upon portions of the wing membrane of that specimen are preserved a very few small short and apparently tubular bodies which have a suggestive resemblance to the quills of small undeveloped feathers such evidences have been diligently sought for professor marsh after examining the wing membranes of a specimen of rampo rincus from sullenhofen stated that the wings were partially folded and naturally contracted into folds and that the surface of the tissue is marked by delicate strie which might easily be taken at first sight for a thin coating of hair closer investigation proved the markings to be minute wrinkles on the under surface of the wing membrane this negative evidence has considerable value because the sullenhofen slate has preserved in the two known examples of the bird archaeopteryx beautiful details of the structure of the larger feathers concerned in flight it has preserved many structures far more delicate there is therefore reason for believing that if the skin had possessed any covering like one of those found in existing vertebrate animals it could scarcely have escaped detection in the numerous undisturbed skeletons of pterodactyls which have been examined the absence of a recognizable covering to the skin in a fossil state cannot be accepted as conclusive evidence of the temperature habits or affinities of the animal although mammalia are almost entirely closed with dense hair which has never been found in a recognizable condition in a fossil state in any specimen of tertiary age one entire order the cetacea show in the smooth hairless skins of whales and porpoises that the class may part with the typical characteristic covering without loss of temperature and without intelligible cause that the absence of hair is not due to the aquatic conditions of rivers or sea is proved by other marine mammals like seals having the skin clothed with a dense growth of hair which is not surpassed in any other order the fineness of the growth of hair in man gives a superficial appearance of the skin being imperfectly clothed and a similar skin in a fossil state might give the impression that it was devoid of hair there are many mammals in which the skin is scannily clothed with hair as the animal grows old neither the elephant nor the armadillo in a fossil state would be likely to have the hair preserved for the growth is thin on the bony shields of the living armadillos yet the difficulty need be no more inherent in the nature of hair than in that of feathers since the hair of the mammoth and rhinoceros has been completely preserved upon their skins in the tundras of Siberia densely clothing the body this may go to show that the pterodactyl possessed a thin covering of hair or more probably that hair was absent since reptiles are equally variable in the clothing of the skin with bony or horny plates and in sometimes having no such protection it may not appear singular that the skin in ornithosaurs has hitherto given no evidence of a covering from analogy a covering might have been expected feathers of birds and hair of mammals are non conducting coverings suited to arrest the loss of heat with the evidence such as it is of resemblance of ornithosaurs to birds in some features of respiration and flight a covering to the skin might have been expected yet the covering may not be necessary to a high temperature of the blood since dr john davie made his observations it has been known that the temperature of the tony above 90 degrees fahrenheit is as warm as the african scaly anteater named the pangolin which has the body more amply protected by its covering this illustration also shows that hot blood may be produced without a four-celled heart with which it is usually associated and that even if the skin in pterodactyls was absolutely naked an active life and an abundant supply of blood could have given the animal a high temperature the circumstance that in several individuals the substance of the wing membrane is preserved would appear to indicate either that it was exceptionally stout when there would have been small chance of resisting decomposition or that its preservation is due to a covering which once existed of fur or down or other clothing substance which has proved more durable than the skin itself end of chapter 12 chapter 13 of dragons of the air by harry sealy this libra vox recording is in the public domain chapter 13 ancient ornithosaurs from the lias kuvie's discourse on the revolutions of the earth made the pterodactyl known to english readers early in the 19th century Dr. Buckland the distinguished professor of geology at oxford discovered in 1829 a far larger specimen in the lias of lime regis and it became known by a figure published by the geological society and by the description in his famous bridge water treatise page 164 this animal was tantalizing in imperfect preservation the bones were scattered in the clay so as to give no idea of the animal's aspect knowledge of its limbs and body has been gradually acquired and now for some years the tale in most parts of the skeleton have been well known in this oldest and most interesting british pterodactyl sir richard oan after some time separated the fossil as a distinct genus named dimorphodon for it was in many ways unlike the pterodactyls described from bavaria the name dimorphodon indicated the two distinct kinds of teeth in the jaws a character which is still unparalleled among pterodactyls of newer age there are a few large pointed piercing and tearing teeth in the front of the jaws with smaller teeth further back placed among the tearing teeth in the upper jaw while in the lower jaw the small teeth are continuous close set and form a fine cutting edge like a saw the dimorphodon has a short beak a deep head and deep lower jaw which is overlapped by the cheekbones the side of the head is occupied by four vacuities separated by narrow bars of bone first in front is the immense opening for the nostril triangular in form with the long upper side following the rounded curve of the face a large triangular opening intervenes between the nose hole and the eye hole scarcely smaller than the former but much larger than the orbit of the eye the eye hole is shaped like a kite or inverted pair further back still is a narrower vertical opening known as the lateral or inferior temporal vacuity the back of the head is badly preserved the two principal skulls differ in depth probably from the strains under which they were pressed flat in the clay a singular detail of structure is found in the extremity of the lower jaw which is turned slightly downward and terminates in a short toothless point the head of dimorphodon is about eight inches long the neck bones are of suitable stoutness and width to support the head the bones are yoked together by strong processes the neck was about six inches long did not include more than seven bones and appeared short owing only to the depth and size of the head the length of the backbone which supported the ribs was also about six inches its joints are remarkably short when compared with those of the neck the tail is about 20 inches long the extreme length of the animal from the tip of the nose to the end of the tail may have been three feet four inches supposing it to have walked on all fours in the manner of a reptile or mammal this may have been a common position but dimorphodon may probably also have been a biped before 1875 when the first restoration appeared in the illustrated London news the legs had been regarded as too short to have supported the animals standing upon its hind limbs they are here seem to be well adapted for such a purpose the upper leg bone is three and one fourth inches long the lower leg bone is four and one half inches long and the singularly strong in-step bones are firmly packed together side by side as in a leaping or jumping mammal and measure one and one half inches in length dimorphodon differs from several other pterodactyls in having the hind limb provided with a fifth outermost short in-step 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 forelimb the digit was manifestly used in the same way as the wing finger in partial support of a flying membrane though its direction may have been upward and outward rather than inward there is no evidence of a pulley joint between the metatarsal and the adjacent phalange the height of the dimorphodon standing on its hind legs in the position of a bird with the wings folded upon the body in the manner of a bird was about 20 inches an ungainly ill balanced animal in aspect but not more so than many big-headed birds and probably capable of resting upon the in-step bones as many birds do the chief point of variation from the pterodactyl wing is in the relative length of the metacarpus in dimorphodon it is shorter than the other bones in the wing never exceeding one and one half inches the total length of all the arm bones down to the point where the metacarpus might have touched the ground or where the wing finger is bent upon it is about nine inches which gives the length of less than six inches below the upper arm bone the four bones of the wing finger measure from the point where the first bone bends upon the metacarpus less than 18 inches so that the wings could only have been carried in the manner of the wings of a bat folded at the side and directed obliquely over the back when the animal moved on all fours its body would appear to have been raised high above the ground in a manner almost unparalleled in reptiles and comparable to birds and mammals dimorphodon is to be imagined in full flight with the body extended like that of a bird when the wings would have had a spread from side to side of about four feet four inches as in other animals of this group the three claws on the front feet are larger than the similar four claws on the hind feet as though the fingers might have functions in grasping prey which were not shared by the toes the restorations give faithful pictures of the skeleton and the form of the body is built upon the indications of muscular structure seen in the bones a second english pterodactyl is found in the upper liais of wittby it is only known from an imperfect skull published in 1888 it has the great advantage of preserving the bones in their natural relations to each other and with a length of head probably similar to dimorphodon shows that the depth at the back of the eye was much less and the skull wants the arched contour of face seen in dimorphodon the head has the same four lateral vacuities but the nostril is relatively small and elongated extending partly above the oval and orbital opening which was larger there is thus a difference of proportion but it is precisely such as might result from the species having the skull flatter the head is easily distinguished by the small nostril which is smaller than the orbit of the eye the animal is referred to another genus the quadrate bones which give attachment to the lower jaw send a process inward to meet the bones of the palate which differ somewhat from the usual condition two bony rods extend from the quadrate bones backward and upward to the sphenoid and two more slender bones extend from the quadrate bones forward and converge in a v shape to define the division between the openings of the nostrils on the palate the v-shaped bone in front is called the vomer while the hinder part is called pterogoid the bones that extend backward to the sphenoid are not easily identified this animal is one of the most interesting of pterodactyls from the very reptilian character exhibited in the back of the head which appears to be different from other specimens which are more like a bird in that region yet underneath this reptilian aspect with the bony bar at the side of the temporal region of the head formed by the squamosal and quadrate bones defining the two temporal vacuities as in reptiles a mold is preserved of the cavity once occupied by the brain showing the chief details of structure of that organ and proving that in so far as it departs from the brain of a bird it appears to resemble the brain of a mammal and is unlike the brain of a reptile the pterodactyls from the lyos of germany are similar to the english types in so far as they can be compared in 1878 i had the opportunity of studying those which were preserved in the castle at bands which professor andreus vognar in 1860 referred to the new genus dorinathus the skull is unknown but the lower jaw six in one half inches long is less than two and one half inches wide at the articulation with the quadrate bone in the skull the depth of the lower jaw does not exceed one fourth inch so that it is in marked contrast to buckland's dimorphodon the synthesis which completely blends the ramai of the jaw is short as far as it extends it contains large tearing teeth followed by smaller teeth behind like those of dimorphodon but this german fossil appears to differ from the english type in having the front of the lower jaw for about three fourths inch compressed from side to side into a sharp blade or spear more marked than in any other pterodactyl and directed upward instead of downward as in dimorphodon nearly all the measurements in the skeleton are practically identical with those of the english dimorphodon and extend to the jaw humorous ulna and radius wing metacarpal first phalange of the wing finger the principal bones of the hind limb appear to be a little shorter but the scapula and coracoid are slightly larger all these bones are so similar informed to dimorphodon that they could not be separated from the lime regis species if they were found in the same locality just as the upper liais in england has yielded a second pterodactyl so the upper liais in germany has yielded a skeleton to which felix pleninger in 1894 gave the name campyloanathis it is an instructive skeleton with the head much smaller than in dimorphodon being less than six inches long but unfortunately broken and disturbed a lower jaw gives the length four and one half inches like the other pterodactyls from the liais it has the extremity of the beak toothless with larger teeth in the region of the symphysis in front and smaller teeth behind the jaw is deeper than in the band specimen from the lower liais but not so deep as in dimorphodon the teeth of the upper jaw vary in size and there appears to be an exceptionally large tooth in the position of the mammalian canine at the junction of the bones named maxillary and intermaxillary the nasal opening is small and elongated as in the english specimen from whitby as in that type there is little or no indication of the convex contour of the face seen in dimorphodon the neck does not appear to be preserved in the back the vertebrae are about three tenths inch long so that 12 which is the usual number would only occupy a length of a little more than three and one half inches the tail is elongated like that of dimorphodon and bordered in the same way by ossified ligaments there are 35 tail vertebrae those which immediately follow the pelvis are short like the vertebrae of the back but they soon elongate and reach a maximum length of nearly one and one half inches at the eighth and then gradually diminish till the last scarcely exceeds one eighth inch in length the length of the tail is about 22 inches this appears to be an inch or two longer than in dimorphodon the longest rib measures two and one half inches and the shortest two inches these ribs probably were connected with the sternum which is imperfectly preserved the bones of the limbs have about the same length as those of dimorphodon so far as they can be compared except that the ulna and radius are shorter the wing metacarpal is of about the same length but the first phalange of the wing finger measures six and one fourth inches the second is about eight and one fourth inches the third six and one half inches and the fourth four and three fourths inches so that the total length of the wing finger was about half an inch short of two feet one character especially deserves attention in the apparent successive elongation of the first three phalanges in the wing finger in dimorphodon the third phalange is the longest in the only specimen in which the finger bones are all preserved usually the first phalange is much longer than the second so that it is a further point of interest to find that this german type shares with dimorphodon a character of the wing finger which distinguishes both from some members of the group by its short first phalange the pelvis is exceptionally strong in campelonathus and although it is crushed the bones manifestly met at the base of the ischium while the pubic bones were separated from each other in front the bones of the hind limb are altogether shorter in the german fossil than in dimorphodon especially in the tibia but the structure of the metatarsis is just the same even to the short fifth metatarsal with its two digits only those bones are extremely short instead of being elongated as in dimorphodon it is therefore convenient from the different proportions of the body that campelonathus may be separated from dimorphodon but so much as is preserved of the english specimen from the upper lyus of whitby rather favors the belief that our species should also be referred to campelonathus which had not been figured when the whitby skull was referred to scaphonathus by mr newton it may be doubtful whether there is sufficient evidence to establish the distinctness of the other german genus dorinathus though it may be retained pending further knowledge in these characters are grounds for placing the lyus pterodactyls in a distinct family the dimorphodontidae as was suggested in 1870 this evidence is found in the five metatarsal bones of which four are in close contact the middle two being slightly the longest so as to present the general aspect of the corresponding bones in a mammal rather than a bird secondly the very slender fibula prolonged down the length of the shin bone which ends in a rounded pulley like the corresponding bone of a bird thirdly the great elongation of the third wing phalange fourthly the prolongation of the coracoid bone beyond the articulation for the humerus as in a bird and the toothless spear shaped beak and jaw with large teeth in front and small teeth behind are also distinctive characters end of chapter 13