FIG. 55. THE LEFT SIDE OF THE PELVIS OF DIMORPHODON SHOWING THE TWO PREPUBIC BONES
The pelvis is exceptionally strong in Campylognathus, 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 metatarsus 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 Campylognathus may be separated from Dimorphodon; but so much as is preserved of the English specimen from the Upper Lias of Whitby rather favours the belief that our species should also be referred to Campylognathus, which had not been figured when the Whitby skull was referred to Scaphognathus by Mr. Newton. It may be doubtful whether there is sufficient evidence to establish the distinctness of the other German genus Dorygnathus, though it may be retained pending further knowledge.
In these characters are grounds for placing the Lias Pterodactyles in a distinct family, the Dimorphodontidæ, 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.
CHAPTER XIV
ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS
RHAMPHOCEPHALUS
The Stonesfield Slate in England, which corresponds in age with the lower part of the Great or Bath Oolite, yields many evidences of terrestrial life—land plants, insects, and mammals—preserved in a marine deposit. A number of isolated bones have been found of Pterodactyles, some of them indicating animals of considerable size and strength. The nature of the limestone was unfavourable to the preservation of soft wing membranes, or even to the bones remaining in natural association. Very little is known of the head of Rhamphocephalus. One imperfect specimen shows a long temporal region which is wide, and a very narrow interspace between the orbits; with a long face, indicated by the extension of narrow nasal bones. The lower jaw has an edentulous beak or spear in front, which is compressed from side to side in the manner of the Liassic forms, but turned upward slightly, as in Dorygnathus or Campylognathus. Behind this extremity are sharp, tall teeth, few in number, which somewhat diminish in size as they extend backward, and do not suddenly change to smaller series, as in the Lias genera. A few small vertebræ have been found, indicating the neck and back. The sacrum consists of five vertebræ. One small example has a length of only an inch. It is a little narrower behind than in front, and would be consistent with the animal having had a long tail, which I believe to have been present, although I have not seen any caudal vertebræ. The early ribs are like the early ribs of a Crocodile or Bird in the well-marked double articulation. The later ribs appear to have but one head. V-shaped abdominal ribs are preserved. Much of the animal is unknown. The coracoid seems to have been directed forward, and, as in a bird, it is 2½ inches long. The humerus is 3½ inches long, and the fore-arm measured 6 inches, so that it was relatively longer than in Dimorphodon. The metacarpus is 1¾ inches long. The wing finger was exceptionally long and strong. Professor Huxley gave its length at 29 inches. My own studies lead to the conclusion that the first finger bone of the wing was the shorter, and that although they did not differ greatly in length, the second was probably the longest, as in Campylognathus.
Professor Huxley makes the second and third phalanges 7¾ inches long, and the first only about 3/8 inch shorter, while the fourth phalange is 6½ inches. These measurements are based upon some specimens in the Oxford University Museum. There is only one first phalange which has a length of 7¾ inches. The others are between 5 and 6 inches, or but little exceed 4 inches; so that as all the fourth phalanges which are known have a length of 6½ inches, it is possible that the normal length of the first phalange in the larger species was 5½ inches. The largest of the phalanges which may be classed as second or third is 8½ inches, and that, I suppose, may have been associated with the 7¾ inches first phalange. But the other bones which could have had this position all measure 5½ and 7¾ inches. The three species indicated by finger bones may have had the measurements:—