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CHAPTER XII 

 MORE ABOUT FOSSILS 



CONTRASTING Strongly with the inflexibility and 

 the permanence of the fundamental characters 

 which delimit and identify each of the phyla or 

 major groups of animals and the consequent absence 

 of any change in their relations to each other from 

 the very earliest times of which we have a record up 

 to the present day is the very great diversity which we 

 see within every major group when we compare the 

 different ages of the past. 



As we trace further and further back the record in 

 the rocks we see fewer and fewer of the kinds of ani- 

 mals we know today and more and more unfamiliar 

 forms, until nearly all the animals are strange and 

 unfamiliar and we find ourselves, lost in astonishment, 

 viewing the relics of a world which seems to have 

 been entirely different from the world we know 

 today. 



And so it was. For instance, in that period known 

 to geologists as the Cretaceous the mammals, though 

 numerous, were all very small and unimportant. The 

 earth was dominated by a most extraordinary and 

 formidable array of reptiles. Chief among these were 

 the dinosaurs of very many different kinds, some of 

 them no larger than a hen, but some of enormous size 

 and in appearance most fantastic and grotesque. 



There were huge horned dinosaurs, strange armored 



