THE BRAIN OF DINOSAURS 



You will remember that the extinct mammals 

 known as Titanotherium and Dinoceras have 

 brains one-eighth the bulk of living mammals 

 of the same size, such as rhinoceros and hippo- 

 potamus. So it was with the huge extinct 

 reptiles. In some the head itself was ridicu- 

 lously small according to our notions of cus- 

 tomary proportion, and even in others, such as 

 Triceratops, where the bony and muscular 

 parts of the head were big, as in a rhinoceros, 

 yet the brain was incredibly small. It could 

 have been passed all along the spinal canal in 

 which the spinal cord lies, and was in proportion 

 to bulk of body a tenth the size of that of a 

 crocodile. Very probably this small size of the 

 brain of great extinct animals has to do with 

 the fact of their ceasing to exist. Animals with 

 bigger and ever increasing brains outdid them 

 in the struggle for existence. 



So much for the Dinosaurs, which might 

 well occupy a complete course of lectures all to 

 themselves. We will now turn to the Thero- 

 morphs , which are an older group even than the 

 Dinosaurs and flourished in the Trias period 

 (see table of strata, p. 60). The Thero- 

 morphs are so called because in some important 



209 p 



