No. 502] HABITS OF SAUROPODOUS DINOSAURS 679 



Osborn 13 has found in the large preacetabular process 

 an argument in favor of the ability of Diplodocus to ele- 

 vate the anterior part of its body. However, Trachodon, 

 which habitually walked on its hind legs has a very insig- 

 nificent preacetabular process. The crocodiles have a 

 strongly developed process in front of the acetabulum. 



It appears to the writer that the structure of the feet 

 of the Sauropoda indicates that the digits were directed 

 somewhat outward, instead of directly forward, as they 

 are placed in the restorations. The strongly developed 

 inner digits would then have come more effectively into 

 contact with the ground than the much reduced outer 

 digits and would have been employed by the animal as a 

 means of pushing itself along. In case the lower end of 

 the radius is placed in front of the ulna, as represented 

 by Hatcher 14 it appears probable that the foot would be 

 directed more strongly outward than is shown in his 

 restoration. 15 



The writer is not aware that any one has held that the 

 Sauropoda could not, at least while resting, assume a 

 crocodile-like posture, with the abdomen on the ground 

 and the limbs extended outward on each side. If such 

 a position is admitted as possible, the arguments derived 

 from the anatomy in favor of an erect mode of walking 

 are greatly weakened. If such a pose was not assumed, 

 what was the pose? Did Diplodocus and Brontosaurus 

 lie down on their sides, as an ox or a horse does when 

 sleeping? Or did they lie prone, with the limbs drawn 

 up under them, as a dog sometimes does ? These posi- 

 tions appear to be improbable. It is worth considering 

 too what disposition Diplodocus made of its elephantine 

 legs while it was swimming with the agility that has been 

 imputed to it. 



The weight of Diplodocus and of Brontosaurus fur- 

 nishes a strong argument against their having had a 



"Mem. Amer. Mus. Nat. Hist., I, p. 210. 

 u Mem. Carnegie Mus., II, p. 73, Fig. 1. 

 13 Op. cit., PL VI. 



