NOTES AND LITERATURE 



SOME RECENT ADVANCES IN VERTEBRATE PALEON- 

 TOLOGY 



The study of the extinct life of the globe must ever be the 

 central and basal point for an understanding of the manner in 

 which evolution has taken place. The ultimate appeal in the 

 theory of descent must necessarily rest with the facts in the 

 history of animal and plant life as it is read from the records 

 in the rocks. Organic evolution is now so firmly established in 

 the minds of present-day scientists that a statement of its 

 truth is no longer needed. But it is well for us to be cautious 

 m our statements about evolution, in not expressing more than 

 we can prove. It is quite possible that the vertebrates come from 

 the arachnoids as Patten contends, but the evidence on this 

 point is wholly lacking. It is also possible, nay even probable, 

 that the crossopterygian ganoids gave rise to the land verte- 

 brates and even a single species of this group may have been 

 such an ancestor, but no one knows whether they did or not 

 and to state, as many of our recent zoological text-books have 

 done, that such was the origin of land vertebrates, is to state 

 what is not known. It is true that the Stegocephali may have 

 given rise to the reptiles, indeed there is very little difference 

 between some of the reptiles and some of the Stegocephali but 

 the proof of the descent of all reptiles from any one. or all of 

 the groups of the Amphibia is more than any one has yet given. 

 The birds may and possibly did arise from the reptiles but the 

 early stages are still unknown. It is the firm belief of many that 

 paleontological proof will be forthcoming for sustaining the 

 ideas expressed by the theory of organic evolution but the facts 

 as they are brought to light by the study of paleontologists do 

 not serve to show that this is true. Smith Woodward says that 

 connecting links or even approximate links between nearly all 

 of the great vertebrate groups are still wanting from our large 

 collections. It may safely be said that 99 per cent, of all the col- 

 lections of fossil vertebrates in the world serve to show diversi- 

 fications of various groups of animals and not to connect them 

 in any satisfactory way. There are, to be sure, connections and 

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