Barbara M. Linde 
Horses in History [PDF ebook] 

Did you know that horses have been around for 55 million years? Of course, they have changed their appearance a lot over the centuries. People have used horses for many different things, from plowing fields to fighting in battles. Readers will learn about the way horses adapted to the changes in their environment over millions of years. They will also explore the special relationship between horses and humans in the United States and throughout the world.