On the Manner of Locomotion of the Dinosaurs, Especially Diplodocus, With Remarks on the Origin of the Birds (Classic Reprint) - Tapa blanda

Sinopsis

Excerpt from On the Manner of Locomotion of the Dinosaurs, Especially Diplodocus, With Remarks on the Origin of the Birds

I grant that Dr. Abel's efforts are along a line where they are needed. Those who believe in the mammal-like gait of Diplodocus ought to give their reasons therefor. I do not assert that reasonable argu ments for their View cannot be produced, but hitherto the correctness of this view has been assumed. The subject is a difficult one and needs to be studied from various points of View and by all who have the Opportunity. And in studying the movements of animals one soon learns that they can assume so many positions that one may be at loss, in the case of an extinct creature, to determine which positions were the usual ones.

In the primitive condition the limbs of the Tetrapoda stand out at right angles with the body,2 and in approximately this position they are found in most Amphibia and Reptilia. When these animals are walking, the humerus and the femur move backward and forward mostly in horizontal planes. In most mammals, on the contrary, the humerus is turned backward against the thorax and the femur forward against the flank. The hand, which otherwise would be directed backward, is turned forward by the crossing Of the bones of the lower arm. The movements of arm and leg are then mostly in sagittal planes. In the duckbill and the echidnas the limbs have retained the position found in most reptiles.

N ow, among all the reptiles that live today there are none, except perhaps the chameleons, that have attained even an approach to the condition found among the mammals.

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