CHAPTER II 



METHODS OF INVESTIGATION — PAL^ONTOLOGICAL 



Palaeontology is the science of ancient life, animal and 

 vegetable, the Zoology and Botany of the past, and deals with 

 fossils. Fossils are the recognizable remains or traces of animals 

 or plants, which were buried in the rocks at the time of the 

 formation of those rocks. In a geological sense, the term rock 

 includes loose and uncompacted materials, such as sand and 

 gravel, as well as solid stone. Granting the possibility of so 

 determining the relative dates of formation of the rocks, that 

 the order of succession of the fossils in time may be ascertained 

 in general terms, the question remains : What use, other than 

 geological, can be made of the fossils? In dealing with this 

 question, attention will be directed almost exclusively to the 

 mammals, the group with which this book is concerned. 



As a preliminary to the discussion, something should be 

 said of the ways in which mammals became entombed in the 

 rocks in which we find them. In this connection it should be 

 remembered that, however firm and sohd those rocks may be 

 now, they were originally layers of loose and uncompacted 

 material, deposited by wind or water, and that each layer 

 formed in its turn the surface of the earth, until buried by fresh 

 accumulations upon it, it may be to enormous depths. 



One method of the entombing of land-mammals, which has 

 frequently been of great importance, is burial in volcanic dust 

 and so-called ash, which has been compacted into firm rock. 

 During a great volcanic eruption enormous quantities of such 

 finely divided material are ejected from the crater and are 

 spread out over the surrounding country, it may be for dis- 



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