4 University of Michigan 



burial and preservation by streams. The character of the 

 teeth shows that the animal lived upon vegetation or hard- 

 shelled molluscs which were crushed by the blunt teeth upon 

 the palatal and dcntary plates. The shortness of the lower 

 limbs shows that the movements were slow, while the stout- 

 ness of the limb bones and girdles indicates great strength. 

 The animal probably lived upon the upland eating hard vege- 

 tation or roots which it excavated with its powerful claws or 

 haunted the banks of upland streams devouring vegetation and 

 hard-shelled molluscs. 



No rational explanation has been given for the enormous 

 development of the neural spines upon a functional basis. It 

 is the opinion of the author, elsewhere expressed, that the 

 spines are a case of physiological overgrowth starting from 

 smaller spines in some ancestral form in which they were of 

 advantage. Living apart from the fierce carnivores of the 

 time, Edaphosaurus had probably found some degree of 

 isolation which permitted the spines once started to increase 

 beyond any size which would have been useful to the indi- 

 vidual. Despite the physiological burden of the exaggerated 

 spines, the animals were for a time successful for not only do 

 the remains occur in considerable quantity but they are found 

 as widely distributed as Oklahoma, Texas, Pennsylvania, and 

 Ohio. 



In the reconstructed skeleton and in the restoration the ani- 

 mal is shown in a normal resting posture with the head only 

 slightly raised, this seems more natural than in a previous 

 reconstruction of the skeleton made at another institution 

 where the animal is shown raised upon the limbs in an attitude 

 which could only have been assumed by an unusual effort and 

 maintained for only a ver}^ brief period. 



