Animals Jlefore Man 



to the apparent average size of extinct animals, 

 for the great majority of fossil vertebrates are 

 bound from the nature of things to be large, 

 or above the average, so that there is a very 

 general tendency to think of the animals of 

 past ages as much larger than they really were. 

 Placed usually with the anomodonts is a 

 group of reptiles from the Permian of Tex- 

 as, distinguished by the great 

 height of the individual sec- 

 tions of the back-bone. The 

 ridge over the shoulders of a 

 horse and the hump of a buf- 

 falo are formed by the very 

 long processes of the back-bone. 

 But long as these are they are 

 greatly exceeded by the pro- 

 cesses on the vertebrae of Di- 

 metrodon and Naosauriis, which 

 must have formed an enormous 

 ridge or keel along the back ; 

 furthermore, in Naosaurus each 

 process bore a series of cross-bars, like the arms 

 on a telegraph pole, standing out at right an- 



132 



A vertebra of No- 

 osaurus, one of 

 the anomodonts. 



