Animals Before Man 



of trilobites being characteristic of the strata 

 forming that series of rocks, while in North 

 America the corres23onding series has the other 

 genus, Dikelloceplialus, Our Middle Cambrian 

 (Acadian epoch) has the Paradoxides fauna, 

 and the Lower Cambrian (Georgian ej)och) the 

 Olenellus fauna. 



The primitive character of the life of the 

 Cambrian period is shown not only by those 

 animals which are clearly simple in their make- 

 up, but by some of those that, at first sight, 

 are apparently complex, such as crustaceans 

 and the many-jointed worms. But in these 

 there is really no complication of structure, 

 only a multiplication of similar parts, one joint 

 being very much like another, bearing the same 

 appendages and having the same uses, so that 

 this has been termed multiplicate structure. 

 We know from fossils that the same animals 

 were found in northern seas and in those of 

 southern latitudes ; hence it is inferred that the 

 climate of the Cambrian era was mild. The 

 unifomiity of distribution of the animal life of 

 the northern hemisphere may, however, be due 



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