CHAPTER XIII 



SOME EARLY MAMMALS AND THE STORY OF THE HORSE 



" Geology, in the magnitude and sublimity of the objects of which it treats, 

 ranks next to astronomy in the scale of the sciences." Sir JOHN F. W. 

 HERSCHEL. 



IT has often been said that the Primary era was an "Age of 

 Fishes," the Secondary era an "Age of Eeptiles," and the 

 Tertiary an " Age of Mammals." There is, however, a danger 

 lest beginners should be deceived by broad statements of this 

 kind, which must not be pressed too far. All that is meant in 

 this case is, that, first of all, fishes were the dominant type ; then 

 reptiles, and then mammals. 



Fishes abounded in the waters of the Primary or Palaeozoic 

 era, while air-breathing amphibians appeared towards its close ; 

 reptiles flourished vigorously all through Secondary or Mesozoic 

 times : and now we are about to show that a marvellous outburst 

 of mammalian life appears to have taken place very early in 

 the Tertiary or Cainozoic era. All this is in accordance with the 

 " Law of Progress " throughout past times, and strongly confirms 

 the theory of Evolution (see pp. 84, 106, 125, and 264). 



The student of geological history soon discovers that mammals 

 of some kind, or kinds, did exist throughout the Secondary era 

 although, judging from their imperfect remains, they must have 

 been of a low type. 1 But the great advance in our knowledge of 



1 Perhaps some of the jaw-bones from Triassic and Jurassic strata represent 

 creatures as low down in the scale as the Monotremes, represented at the 

 present day by the Duck-bill Platypus and the Echidna of Australia. 



