EVIDENCE OF FOSSIL REMAINS 97 



to become a little more reduced and the middle one to 

 enlarge slightly to give the one-toed limb of modern 

 types, with its splint-like vestiges still in evidence to 

 show that the ancestor's foot comprised more of 

 these terminal elements. Comparing the animals of 

 successive periods, these and other skeletal structures 

 demonstrate that the ancestry of each group of species 

 is to be found in the animals of the preceding epoch, 

 and that the whole history of horses is one of natural 

 transformation, in a word, of evolution. 



No less interesting in their own way are the remains 

 of other hoofed forms that lead down to the elephants 

 of to-day and to the mammoth and mastodon of rela- 

 tively recent geologic times. Common sense would 

 lead to the conclusion that a form like a modern tapir 

 was the prototype from which these creatures have 

 arisen, and common sense would lead us to expect that 

 if any fossils of the ancestors of the modern group 

 of elephants occurred at all they would be like tapirs. 

 Thus a fossil of much significance in this connection is 

 Mceritherium, whose remains have been found in the 

 rocks exposed in the Libyan desert, for this creature 

 was practically a tapir, while at the same time its 

 characters of muzzle and tusk mark it as very close 

 to the ancestors of the larger woolly elephants of later 

 geological times, when the trunk had grown consider- 

 ably and the tusks had become greatly prolonged. 

 Again the fossil sequence confirms the conclusions 

 of comparative anatomy, regarding the mode by which 

 certain modern animals have evolved. 



The fossil deer of North America, as well as many 

 other even-toed members of the group of mammalia 



