412 



THE AMEBIC AN NATURALIST [Vol. XL V 



play in. It seems quite doubtful whether the carnivorous 

 dinosaurs of even the Jurassic period had the erect 

 bird-like bearing that is usually attributed to them. 

 The extraordinary development of the pubic bones of 

 Ceratosaurns, whose expanded and ankylosed distal ends 

 reached nearly half-way to the fore legs, 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. 



Dr. Matthew thinks that the sanropods had too great 

 a bulk to have lived on land. The law to which he gives 

 expression does, of course, prescribe a limit to the size an 

 animal can attain, but who has yet determined what 

 that limit is? Larger elephants have lived than those 

 now living, and it is not certain that we have discovered 

 yet the largest that have lived. Animals do not attain 

 a great size simply to test the laws of mechanics. 



