222 ANIMALS OF THE PAST 



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, cli- 

 matic change, modifying even a comparatively 

 limited area, would suffice to sweep them out 

 of existence. 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 remembered 

 that this very fate is believed to have overtaken 

 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 Ich- 

 thyosaurs, of Europe, the Plesiosaurs and Mo- 

 sasaurs, 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 



