Advances in Reptilian PalÆontology

Abstract

IN the July number of The American Naturalist Dr. O. P. Hay reopens the discussion with regard to the position of the limbs in Diplodocus and other sauropod dinosaurs, criticising the views of those who assert that these reptiles carried themselves in elephantine fashion, and maintaining his own opinion that the general pose was more after the crocodilian style. In regard to what may be called the elephant pose, it is pointed out that since a straight femur appears to have characterised the Proboscidea from the beginning, its occurrence in the modern representatives of the group may be regarded as a primitive feature, rather than an adaptation to the support of great bodily weig'ht. At the conclusion of his arguments with regard to the pose of the sauropods, Mr. Hay expresses doubts as to whether the erect bird-like posture attributed to the carnivorous dinosaurs of the Jurassic is really true to nature. “The extraordinary development of the pubic bones of Aristosaurus, the expanded and anky-losed distal ends of which reached nearly half-way to the forelegs, seems to me to indicate that these animals, when in repose, had a prone position, resting much of the weight on the pubes, and that when running their legs straddled considerably.”