ANCESTRY OF THE MAMMALIA 



Therocephalian Ancestor 



47 



Aelurosuchus 



Mammalian 

 Ancestor Sesamodon 



GaTesaurus 

 Nythosaurus 



Cynognathus 



Diademodon 



Gomphognathus 



Fig. 9. — Genetic relationships of the principal known Cynodonts. (After Broom.) 



and greater activity. It is Broom's interesting surmise that 

 this greater activity ultimately brought about the develop- 

 ment of the warm-blooded Mammals. 



