222 ANIMALS OF THE PAST 
the big Titanotheres flourished, it is easy to see 
from a glance at their large, simple teeth i 
that these beasts needed an ample provision of — 
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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 
