THE "OSTRICH" DINOSAUR AND THE "TYRANT" DINOSAUR 7 



A Dinosaur Skull and a Bird Skull. — A — Skull of the "ostrich mimic" dinosaur. Bones of the back 

 and lower jaw, and bony ring surrounding the eye socket (orb.). B — Skull of the existing ostrich 

 (iStruthio) , to the same scale of size. 



Comparii-on shows that the "ostrich mimic'' dinosaur was not carnivorous, but tliat the jaws had been 

 converted into a narrow, horny beak, not unlike that of the present-day ostrich, for eating some kind of 

 soft food 



Alberta, Canada. This type was named 

 Ornitliomimus alius, "the tall bird 

 mimic," by Lambe, of the Canadian 

 Survey. The geologic formation in 

 which these supposed "bird-mimic" 

 limb bones were found is considerably 

 more ancient than the Denver Basin in 

 which Marsh's type was discovered. 



In 1902 the American Museum ex- 

 ploring parties entered this rich field 

 of Upper Cretaceous dinosaur life in 

 northern Montana and in 1909 in 

 southern Alberta. Remains of the 

 "bird mimics" proved to be extremely 

 rare; but year after year the trying 

 search was kept up in the hope of 

 discovering a complete skeleton and 

 of finally solving thereby the riddle 



of the life habits of this remarkable 

 family of dinosaurs. Barnum Brown 

 who was in charge of the field par- 

 ties observed that these bones are 

 almost invariably found in ancient 

 shore deposits, indicated by wave ripple 

 marks in the sandstones, mingled with 

 remains of mollusks and of various 

 forms of shore-living plant life, which 

 affords evidence that these "bird mim- 

 ics" lived along the seashores and sub- 

 sisted on the animals exposed by the 

 rising and falling tides. Finally, in 

 1914, the prolonged search was re- 

 warded by the discovery of a complete 

 skeleton of one of these animals. The 

 specimen was exhumed with the great- 

 est care and brought to the Museum in 



