THE CENTURY'S PROGRESS IX PALEONTOLOGY 



Not all the strange beasts which have left their re- 

 mains in our " bad lands " are represented by living de- 

 scendants. The titanotheres, or brontotheridae, for ex- 

 ample, a gigantic tribe, off shoots of the same stock 

 which produced the horse and rhinoceros, represented 

 the culmination of a line of descent. They developed 

 rapidly in a geological sense, and flourished about the 

 middle of the tertiary period ; then, to use Agassiz's 

 phrase, " time fought against them." The story of their 

 evolution has been worked out by Professors Leidy, 

 Marsh, Cope, and H. F. Osborne. 



The very latest bit of paleontological evidence bear- 

 ing on the question of the introduction of species is that 

 presented by Dr. J. L. Wortman in connection with the 

 fossil lineage of the edentates. It was suggested by 

 Marsh, in 1877, that these creatures, whose modern rep- 

 resentatives are all South American, originated in North. 

 America long before the two continents had any land 

 connection. The stages of degeneration by which these 

 animals gradually lost the enamel from their teeth, com- 

 ing finally to the unique condition of their modern de- 

 scendants of the sloth tribe, are illustrated by strikingly 

 graded specimens now preserved in the American Mu- 

 seum of Natural History, as shown by Dr. Wortman. 



All these and a multitude of other recent observations 

 that cannot be even outlined here tell the same story 

 With one accord paleontologists of our time regard the 

 question of the introduction of new species as solved. 

 As Professor Marsh has said, " to doubt evolution to- 

 day is to doubt science ; and science is only another 

 name for truth." 



Thus the third great battle over the meaning of the 

 fossil records has come to a conclusion. Again there 



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