142 Biology in America 



infancy, and great was the travail of the earth in bringing 

 them forth, for several active volcanoes marked their course. 

 From these, great clouds of ashes were hurled forth to set- 

 tle upon earth and water. Such was the home of the creo- 

 donts, the forerunners of modern Carnivora. Of these the 

 Miacidse are believed to represent the progressive branch des- 

 tined to flourish and bring forth fruit, while the other 

 branches have withered and died. They were creatures much 

 like the modern carnivores in general appearance, but with 

 small brain-case and a very high ridge on the upper side of 

 the skull for attachment of the powerful jaw muscles, and 

 the teeth were not so well formed for eating flesh as in mod- 

 ern carnivores. Remains of the Miacidae have been found 

 from Wyoming to New Mexico. As in many another case of 

 evolution in animals, the old adage " great oaks from little 

 acorns grow" applied to the Miacidae, for the forerunners 

 of the ' * king of beasts ' ' and the man-eating tiger were little 

 fellows content to prey on smaller fry of field and forest. 

 Many of their relatives however were larger fellows, equalling 

 in size a small bear. Associated with the creodonts were 

 other creatures, many of them of huge size and ungainly 

 form. Here shambled the coryphodonts, ugly brutes, equal- 

 ling a small rhinoceros in size and somewhat resembling a 

 hippopotamus in form, with heavy tusks, elephantine feet 

 and short, heavy legs, and Uintatherium, a creature so bizarre 

 in form that it seems as if Nature had designed it to grace a 

 palseontological dime museum. The skull of this beast, not 

 being able to find room for growth along ordinary lines, ran 

 riot in the matter of horns. He had horns on his snout and 

 horns on his forehead and horns at the back of his head and 

 as if these were not enough to gratify his propensity for 

 horny embellishment, his upper canine teeth were prolonged 

 into great tusks, or horns turned upside down. The female 

 however was much more conservative in the matter of horns, 

 while she lacked the tusks entirely. The general form of 

 the beast was quite similar to that of its relatives, the cory- 

 phodonts. Beside these ungainly beasts there were others 

 resembling the present sloths of South America and repre- 

 sentatives of the modern shrews and moles. 



As in the case of man the aborigine has given place to 

 the invader from distant lands, so too the primitive mammals 

 of North America, which were natives of the country, have 

 been displaced by more recent types which have immigrated 

 from other regions. Whence they came cannot certainly be 

 determined, but probably Asia was their birthplace, whence 

 like the human race they have wandered throughout the 

 world. It has repeatedly happened in geologic history that 



