A Review of Some Recent Criticisms...
...of the Restorations of Sauropod Dinosaurs Existing in the Museums of the United States, with Special Reference to that of Diplodocus carnegiei in the Carnegie Museum
Continued from Part One
Inasmuch, however, as Professor Tornier's opinions and his misleading diagrams and figures have been given some currency in journals intended to popularize science, it seems to the speaker that the present is a suitable occasion in which not merely to demonstrate the utterly absurd character of the opinions of Hay, Tornier, and Sternfeld, but also to bring out into clearer light the reasons why American paleontologists, and for that matter the leading paleontologists of Europe also, have concurred in regarding the sauropod dinosaurs as having possessed the power to assume the position which has hitherto been given them. At the risk, therefore, of occupying some of your precious time I wish to take up the subject a little more thoroughly and by the help of a series of illustrations to make my meaning clear.
I shall begin with the structure of the pelvis in the sauropod dinosaurs. I herewith give illustrations (Fig. 4) taken from the specimens in the Carnegie Museum of the pelves of Brontosaurus, Diplodocus, and Haplocanthosaurus, the last closely allied to Cetiosaurus of Owen.
Fig. 4. 1, pelvis of Brontosaurus ; 2, pelvis of Diplodocus ; 3, pelvis of Haplocanthosaurus. From specimens at the Carnegie Museum.
Any one who has a merely rudimentary knowledge of the pelves of the dinosauria in general knows that they are distinctly ornithic in type, and not lacertilian, nor crocodilian, Professor Tornier to the contrary notwithstanding. Seeing is believing, and I also give illustrations of the pelvis of a crocodile, of Varanus, of Iguana, and of Uromastrix (Figs. 5–8).
Fig. 5. Pelvis and hind limb of crocodile.
Fig. 6. Pelvis of Varanus.
Compare these for a moment with the pelves of the huge sauropod reptiles and you see immediately that there is an enormous difference in general, and in countless details, which it is not worth while to consume your time in describing.
Fig. 7. Pelvis of Iguana. I, Ilium; h, Head of femur; 2t, Second trochanter.
Fig. 8. Pelvis of Uromastrix.
Taking up now the articulation of the femur with the acetabulum of the pelvis, we discover in the first place that the head of the femur in the lacertilia differs remarkably from the head of the femur in the sauropoda. In the lacertilia the greater trochanter is reduced in size and in some genera is practically obsolete; when present and articulated it looks backward, downward, inward. On the other hand, the second trochanter in the recent lacertilia is enormously develpoed, looking downward, forward, and outward (see Fig. 7). In the sauropoda, as in ratite birds, the second trochanter is obsolescent or wholly obsolete. The illustrations already given may help to make my meaning clear. In this connection it is well to study the head of the femur and the structure of the pelvis in the struthious birds. The analogy between these and the dinosauria has often been pointed out. The facts to which I have called your attention have great anatomical significance. A comparison of the head of the femur of the crawling reptiles of to-day with the femur of the sauropoda shows at a glance that in the latter the proximal end of the femur is more like that of birds than of recent lizards. It was, as we all know, in consequence of the recognized similarity of the pelvic girdle an the head of the femur to the corresponding structures in the ratite birds that Owen, Marsh and all other competent students have assigned the femur the position which has almost uniformly been given to it in restorations of the sauropoda, as well as of other dinosaurs.
But let us for the sake of experiment give the femur the same relative position which it has in the lacertilia, in which the second trochanter plays so great a part. To do this it is necessary to rotate the head of the femur in such a way that the greater trochanter will point downward and backward. The accompanying diagrammatic illustration shows the femur of the Diplodocus adapted to the acetabulum after the analogy of Varanus and Iguana (Fig. 9).
Fig. 9. The hind limbs of Diplodocus arranged after the analogy of the recent lacertilia.
Of what earthly use the hind limb of Diplodocus could have been to him in such a position I leave you to determine to yourselves. It has been suggested that kindly nature, to meet the requirements of the case, must have channeled the surface of the earth and provided the Diplodocus and its allies with troughs in which they kept their bodies while the feet were employed for locomotion along the banks. The Diplodocus must have moved in a groove or a rut. This might perhaps account for his early extinction. It is physically and mentally bad to "get into a rut."
Assuming that the articulation of the femur after all was not as it is in the lacertilia, and accepting, merely for the sake of argument, the pose of Professor Tornier, who, though contending that the creature was a lacertilian—"ein Eidechse"—nevertheless, constrained by obvious difficulties, in his drawings does not give the femur the characteristically lacertilian pose, I have taken pains to place the bones of the replica of the Diplodocus now in course of preparation for the Imperial Academy at St. Petersburg as nearly as is possible in the position which Professor Tornier demands that they should have. I have accepted Tornier's "richtige Stellung" for the time being, and have collocated the bones in the position which he demands for them, and I have the pleasure herewith of submitting to you photographs of the bones thus located (Figs. 10 and 11).
Fig. 10. View from behind of pelvis and femur of Diplodocus mounted according to the Tornierian prescription. i.p, Ischial peduncle; g.t, great trochanter; a.p, acetabular surface of the pubis; a.i, acetabular face of the ischium.
In the first place you will observe that it is beyond possibility, whn locating the bones in this manner, to bring about anything like a plausible position of the head of the femur in the acetabulum. The ridiculous articulation of the great trochanter with the ischial peduncle demanded by Professor Tornier, who seems to have mistaken the ischial peduncle for an anti-trochanter, has already been alluded to. Of course we could not accomplish such an articulation, but we have come as near to it as the bones will allow. Placed as nearly as is possible in the situation in which Professor Tornier demands that the bones shall be put, the head of the femur stands in no relation whatever to the articuating surfaces of those portions of the pubis and the ischium (a.p and a.i) which enter into the composition of the acetabulum. The lower surface of the head of the femur is left out of all relation to these obviously articulating surfaces at a remove from them of at least six inches. Furthermore, in swinging the bones into the acetabulum in such a way as to throw the distal end outward, the head of the femur necessary enters and penetrates the opening of the acetabulum, invading the pelvic cavity and occluding the same. But this is not the worst. The distal end of the femur is left, as Tornier's figures themselves show, protruding into space without any surface whatever with which to articulate.
Fig. 11. View from side and front of femur and pelvis of Diplodocus mounted after the Tornierian prescription.
I am fully aware that in the lacertilia the joint made by the femur with the tibia and fibula, especially in young individuals, is provided to a high degree with cartilaginous connections, and the ends of the bones are covered with great cartilaginous epiphyses, which in the bones of the fossil animals we are considering have not been petrified and preserved, but making all allowance for the existence of these cartilaginous masses at the points indicated, it is impossible to conceive that the broad expanded heads of the tibia and fibula should merely come in contact with the internal and external condyles of the femur at two small points, in each case not larger than a sixpence. The pose given to these bones by Dr. Tornier represents nothing else than the complete dislocation of the femur from the tibia and fibula.
Dr. Holland keeps it coming in Part Three.