THE "OSTRICH" DINOSAUR AND THE "TYRANT" DINOSAUR 



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that of the ostriches, and of the Cre- 

 taceous diving bird known as "Iles- 

 perornis." Such a long, slender neck 

 is in widest contrast to that of the giant 

 carnivorous dinosaur Tyrannomurus. 

 This ancient type, the "bird mimic,"' 



new and consistent theory of adapta- 

 tion — namel}', that this animal had 

 actually come to mimic the ostriches 

 both in its structure and in its browsing 

 habits, were it not for the very pecu- 

 liar and unique structure of the fore 



The "Ostrich Mimic" Dinosaur, Struthiomimus . — A — Theory of the running pose based upon the 

 flight of modern lizards. B — Theory of the anthill-attacking pose 



is found to possess in the hind feet por- 

 tions of an additional toe, which is not 

 present in the original Ornithomimus 

 specimen, and in view of the close re- 

 semblances which the animal presents 

 in its skull, neck, and hind limbs to the 

 existing ostriches, rheas, and other 

 struthious birds, the author decided to 

 name it the "ostrich mimic," Struthio- 

 mimus. 



The way would be quite clear for a 



limb and hand, which are almost as 

 much unlike those of the carnivorous 

 dinosaurs as they are unlike the wing 

 of the ostrich. It resembles, on the 

 contrary, in some respects the fore limb 

 of the peaceful herbivorous tree sloths 

 of South America, such as the three- 

 toed sloth Bradyjms, or the two-toed 

 sloth Choloepus. The arm and forearm 

 are long and relatively slender, as in 

 the three-toed sloth, while the hand 



