HoiD the History of the Past I^ Read 



footprints may show not only whether they 

 were made by mammals, bMs, reptiles, or ba- 

 trachians, but even indicate the particular divi- 

 sion to which the individual making them be- 

 longed. But the feet of some dinosaurs were 

 so much like those of birds that for many years 

 the tracks made by them were ascribed to 

 gigantic birds. Close observers, however, point- 

 ed out that some of the finest impressions 

 showed that the texture of the skin was quite 

 different from that covering the feet of birds, 

 while in most cases the bones of the toes were 

 shorter and heavier, and subsequent discoveries 

 have made it clear that these footprints are 

 those of dinosaurs. 



Very often tracks are all w^e have to tell 

 that some animals ever existed, for their bones 

 were either destroyed or lie buried deep in the 

 rocks in places now inaccessible. A well-known 

 instance is tliat of the famous footprints in the 

 red sandstone of the Connecticut Valley, which 

 bear testimony of the presence of a host of ani- 

 mals, great and small, but two or three of 

 which have ever come to light. When these 



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