Chapter 2 

 MAMMALS* 



The origin of the Mammalia, or hairy warm-blooded animals 

 was many millions of years ago, in the earlier part of the Mesozoic 

 age. The fossil cynodont (dog-toothed) reptiles of South Africa 

 seem to point the way to mammalian evolution. They had, at 

 all events, two occipital condyles (articulating with the first 

 vertebra), and their teeth were distinctly differentiated into inci- 

 sors, canines, premolars and molars. The duck-bill of Australia 

 is a mammal which retains the reptilian feature of laying eggs. 

 Where the first mammal actually developed, we do not know, and 

 probably never will know, but some very ancient and primitive forms 

 have been found in Rocky Mountain strata. These animals were 

 small and insignificant, while the reptiles, represented by gigantic 

 dinosaurs, appeared to be lords of the earth. In a Drama of Evo- 

 lution we have imagined a conversation between the dinosaur 

 Brontosaurus and a primitive mammal; 



Brontosaurus. 



But look you, little beast, your blood is warm, 



Your skin is hairy, and though small you swarm 



Through glade and forest. 



In all past since Cambrian dawn, 



Through all the changeful weary days, 



Enduring night for hopeful morn, 



Was never such a craze. You do upset 



The whole great scheme of progress, and forget 



The lessons of the elder days. 



Primitive Mammal. 



Great sir, we see in you and yours 



Creation's finished work. 'Tis not for us 



To emulate your greatness. Yet we would try 



A line of progress all our own, and by and by 



In ages yet to come evolve a man, 



A being who with winged thought may span 



The starry skies, and as in time he dies 



Soar thither as a soul! 



*See especially E. R. Warren, The Mammals of Colorado (1910). 



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