176 ANIMALS OF THE PAST 



Triceratops, had evidently carried specialization to an 

 extreme, while in turn the carnivorous forms must have 

 required an abundant supply of slow and easily cap- 

 tured prey. 



Coming down to a more recent epoch, when the big 

 Titanotheres flourished, it is easy to see from a glance 

 at their large, simple teeth that these beasts needed an 

 ample provision of coarse vegetation, and as they seem 

 never to have spread far beyond their birthplace, 

 climatic change, modifying even a comparatively 

 limited area, would suffice to sweep them out of exist- 

 ence. To use the epitaph proposed by Professor Marsh 

 for the tombstone of one of the Dinosaurs, many a 

 beast might say, "I, and my race perished of over 

 specialization." To revert to the horse it will be re- 

 membered that this very fate is believed to have over- 

 taken those almost horses the European Hippotheres; 

 they reached a point where no further progress was 

 possible, and fell by the wayside. 



There is, however, still another class of cases where 

 species, families, orders, even, seem to have passed out 

 of existence without sufficient cause. Those great 

 marine reptiles, the Ichthyosaurs, of Europe, the Plesio- 

 saurs and Mosasaurs, of our own continent, seem to 

 have been just as well adapted to an aquatic life as the 

 whales, and even better than the seals, and we can see 

 no reason why Columbus should not have found these 

 creatures still disporting themselves in the Gulf of 

 Mexico. The best we can do is to fall back on an un- 

 known "law of progress," and say that the trend of life 

 is toward the replacement of large, lower animals by 

 those smaller and intellectually higher. 



But why there should be an allotted course to any 

 group of animals, why some species come to an end when 

 they are seemingly as well fitted to endure as others now 



