VERTEBRATE PALEONTOLOGY IN 1910 679 



corresponding articular surfaces of the latter. After a reference 

 to the extraordinary position which would be assumed in 

 certain circumstances by the fore-limbs oi Diplodocus according 

 to Tornier's restoration, Dr. Holland maintains that the form 

 given to the limbs in the restored skeleton in the museum under 

 his charge is, in all essential features, true to nature. 



A second and more elaborate contribution to the subject 

 was made by Dr. W. T. Matthew in the American Naturalist, 

 vol. xliv. pp. 547-60. That sauropods walked, instead of 

 crawling, the author considers fully proved, their limb-structure, 

 as already pointed out by Dr. Abel, displaying a remarkable 

 parallelism to that of proboscideans. This rectigrade type, in 

 which the whole limb is pillar-like, with the foot short, rounded, 

 and heavily padded, and the toes reduced or rudimentary, 

 appears to be an attribute of animals of great bodily size, the 

 movements being chiefly restricted to the upper joints, and 

 the foot serving mainly as a cushion to minimise the shock. 

 A structure of this kind will obviously occur only among 

 animals which habitually rest their weight on the limbs alone. 

 A limit is, however, soon reached in regard to the weight which 

 even the most powerful limbs are capable of supporting in the 

 case of a purely terrestrial animal, and this limit appears to 

 have been attained among the elephants. If this be so, there 

 arises the question why sauropod dinosaurs, with their less 

 perfectly formed limbs, vastly exceeded the largest elephants 

 in bulk and stature. The answer, according to Dr. Matthew, 

 is that these reptiles were aquatic, and adapted to wading. 

 "A wading animal," he observes, "has the greater part of its 

 weight buoyed up by the water, and might attain a much larger 

 size without transcending its mechanical limitations, just as 

 the whales and some true fishes attain a much larger size than 

 any land animal." 



On the other hand. Dr. O. Jaekel, in a paper published in 

 the Monatsbericht. deiitsch. geol. Ges., vol. Ixii. pp. 2yo-yy, 

 maintains that the foregoing views are quite wrong, and that 

 sauropod dinosaurs moved on their limbs after the fashion of 

 lizards; this opinion being apparently based in part on a 

 skeleton of the hind-limb of Piateosaurus, in which the bones 

 are believed to retain their natural position, and in which the 

 femur is nearly horizontal. 



Somewhat similar views are expressed by Mr. O. P. Hay, 



