Simpson, George Gaylord,  1902- <br/><br/>
Horses :  the story of the horse family in the modern world and through sixty million years of history / 
George Gaylord Simpson. 
 - New York :  Oxford University Press,  1951. 
 - xxiv, 247 p. :  ill. ;  24 cm. 
<br/><br/>p. 232-236. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Horses--History.<br/>Horses, Fossil.<br/>Mammals--Evolution.