CHAPTER V 



PAST HISTORY OF ANIMALS 



(Palaeontology) 



In the two preceding chapters we have noticed two of the 

 great records of the history of animal Hfe — that preserved 

 in observable structures, and the modified recapitulation 

 discernible in individual development ; in this we turn to 

 the third — the geological record. In the early days of the 

 Evolution theory the modern science of Embryology was 

 still in its infancy, and could furnish few arguments, and it 

 was the opponents of the new theory rather than its sup- 

 porters who appealed to Palaeontology. They asserted that 

 the palaeontological facts refused to lend the support which 

 the theory demanded. To their attacks the evolutionists 

 usually replied by pointing out that the geological record 

 was very incomplete. The numerous investigations which 

 have since been carried on on all sides now show con- 

 clusively that it was imperfection rather of knowledge than 

 of the record which produced the negative results. We 

 must, however, still acknowledge that, except in a few 

 cases, there is but little certainty as to the precise pedi- 

 gree of living animals, and seek for reasons to explain this. 

 "Imperfection of the geological record." — If we re- 

 member the rule of modern Geology, that the past is to 

 be interpreted by the aid of the present, there can be no 

 difficulty in realising that the chances against the preserva- 

 tion of any given animal are very great. Many are destroyed 

 by other living creatures, or obliterated by chemical agencies. 

 Except in rare instances, only hard parts, such as bones, 

 teeth, and shells, are likely to be preserved, and this at once 



greatly limits the evidential value of fossils. The primitive 



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