THE POSE AND LOCOMOTION OF DIPLODOCUS 23 



about over rocks and shrubs and the limbs of trees. Possibly the 

 primitive birds, although not more than many lizards, strictly arboreal, 

 often found safety and repose amid the branches and leaves of the 

 Triassic ferns, calamites, and conifers. Possessing a fringe of feath- 

 ers on their arms, they soon found these of advantage when they were 

 running or making leaps to catch their prey or to escape capture by 

 their enemies. When once they had made this discovery, the race 

 entered on the conquest of the realms of the air. 



It will be observed that the writer, in opposition to Dr. Francis 

 Nopcsa 16 holds that the primitive birds became bipedal while they 

 were learning to fly and because of it, instead of becoming so long 

 before the flying habit was initiated. It will be observed that the 

 fore limbs of Dr. Nopcsa's "Pro-avis" are already greatly reduced, 

 and it might be questioned whether such limbs could be rejuvenated. 

 It is certain that the ostriches have for untold generations been flap- 

 ping their wings, to aid in running, but these limbs have steadily 

 degenerated. 



As believed by Dr. v. Huene, the Orthopoda probably took their 

 origin from the Theropoda v If the views expressed by the present 

 writer are true or approach truth, birds came on the arena before 

 either of the suborders of dinosaurs just named; and hence most of 

 the characters which have suggested relationship between the birds 

 and the dinosaurs, which characters have been so clearly presented 

 by Dollo and Nopcsa in the papers already quoted, have all arisen 

 independently in the two groups as a result of their starting from the 

 same goal and speeding in nearly the same direction. On the other 

 hand, the sauropods are nearest the stock from which sprang the birds, 

 and it is in their skeletons that we must seek for the primitive common 

 characters. 



To the writer it seems probable that the avidinosaurs were not 

 amphibious animals, but dwellers on the land. It is not likely that 

 wings were developed on animals that lived much in the water. The 

 Theropoda and the Orthopoda continued to inhabit the land, although 

 this did not prevent them from seeking their food in swamps or from 

 refreshing themselves in the water. After the sauropods had attained 

 such bulk that locomotion on the land became troublesome they 



18 Proc. Zool. Soc. London, 1907, p. 234. 



