FIG. 57. RESTORATION OF THE SKELETON OF SCAPHOGNATHUS CRASSIROSTRIS
Published in the Illustrated London News in 1875. In which a tail is shown on the evidence of the structure of the head and hand
The great German delineator of these animals, Von Meyer, admitted six different species. Mr. Newton and Mr. Lydekker diminish the number to four. It is not easy to determine these differences, or to say how far the differences observed in the bones characterise species or genera. It is certain that there is one remarkable difference from other and older Pterodactyles, in that the last or fourth bone in the wing finger is usually slightly longer than the third bone, which precedes it. There is a certain variability in the specimens which makes discussion of their characters difficult, and has led to some forms being regarded as varieties, while others, of which less material is available, are classed as species. I am disposed to say that some of the confusion may have resulted from specimens being wrongly named. Thus, there is a Rhamphorhynchus called curtimanus, or the form with the short hand. It is represented by two types. One of these appears to have the humerus short, the ulna and radius long, and the finger bones long; the other has the humerus longer, the ulna much shorter, and the finger bones shorter. They are clearly different species, but the second variety agrees in almost every detail with a species named hirundinaceus, the swallow-like Rhamphorhynchus. This identification shows, not that the latter is a bad species, but that curtimanus is a distinct species which had sometimes been confounded with the other. While most of these specimens show a small but steady decrease in the length of the several wing finger bones, the species called Gemmingi has the first three bones absolutely equal and shorter than in the species curtimanus, longimanus, or hirundinaceus. In the same way, on the evidence of facts, I find myself unable to join in discarding Professor Marsh's species phyllurus, on account of the different proportions of its limb bones. The humerus, metacarpus, and third phalange of the wing finger in Rhamphorhynchus phyllurus are exceptionally short as compared with other species. Everyone agrees that the species called longicaudus is a distinct one, so that it is chiefly in slight differences in the proportions of constituent parts of the skeleton that the types of the Rhamphorhynchus are distinguished from each other. I cannot quite concur with either Professor Zittel ([Fig. 58, 3]) or Professor Marsh ([Fig. 58, 2]) in the expansion which they give to the wing membrane in their restorations; for although Professor Zittel represents the tail as free from the hind legs, while Professor Marsh connects them together, they both concur in carrying the wing membrane from the tip of the wing finger down to the extremity of the ankle joint. I should have preferred to carry it no further down the body than the lower part of the back, there being no fossil evidence in favour of this extension so far as specimens have been described. Neither the membranous wings figured by Zittel nor by Marsh would warrant so much body membrane as the Rhamphorhynchus has been credited with. I have based my restoration ([p. 161]) of the skeleton chiefly on Rhamphorhynchus phyllurus.
1. Ramphocephalus. Stonesfield Slate. John Phillips, 1871
2. Rhamphorhynchus. O. C. Marsh, 1882
3. Rhamphorhynchus. V. Zittel, 1882
4. Ornithostoma. Williston, 1897
5. Dimorphodon. Buckland, 1836. Tail then unknown
6. Ornithocheirus. H. G. Seeley, 1865
THE SHORT-TAILED TYPES
The Pterodactylia are less variable; and the variation among the species is chiefly confined to relative length of the head, length of the neck, and the height of the body above the ground. The tail is always so short as to be inappreciable. Many of the specimens are fragmentary, and the characters of the group are not easily determined without careful comparisons and measurements. The bones of the fore limb and wing finger are less stout than in the Rhamphorhynchus type, while the femur is generally a little longer than the humerus, and the wing finger is short in comparison with its condition in Rhamphorhynchus. These short-tailed Pterodactyles give the impression of being active little animals, having very much the aspect of birds, upon four legs or two. The neck is about as long as the lower jaw, the antorbital vacuity in the head is imperfectly separated from the much larger nasal opening, the orbit of the eye is large and far back, the teeth are entirely in front of the nasal aperture, and the post-orbital vacuity is minute and inconspicuous. The sternum is much wider than long, and no specimens give evidence of a manubrium. The finger bones progressively decrease in length. The prepubic bones have a partially expanded fan-like form, and never show the triradiate shape, and are never anchylosed. 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 1½ inches to its back standing on all fours, and but little over 2½ inches standing as a biped, on the hind limbs.
A restoration of the species called Pterodactylus scolopaciceps, published in 1875 in the Illustrated London News in the position of a quadruped, shows an animal a little larger, with a body 2½ inches high and 6 to 7 inches long, with the wing finger 4½ inches long. Larger animals occur in the same deposit, and in one named Pterodactylus grandis the leg bones are a foot long; and such an animal may have been nearly a foot in height to its back, standing as a quadruped, though most of these animals had the neck flexible and capable of being raised like the neck of a Goose or a Deer ([p. 30]), and bent down like a Duck's when feeding.