The Hagerman horse is the earliest known representative of what would eventually become the animal we are familiar with today. It is believed that this horse was more closely related to Grevy's Zebra that now lives in Africa rather than to domestically bred horses.
It was about the same size as a modern day zebra, approximately 110-145 centimeters (43 to 57 inches) tall at the shoulder. It weighted between 110 and 385 kilograms (385 to 847 pounds).
Hagerman Horse (left), Grevy's Zebra (center), Modern Thoroughbred (right)
The Hagerman horse was only one stage in the continuing evolution of horses. The animal continued to evolve on the North American continent until the late Pliestocene period, about 10,000 years ago. Then, like camels, and several other large bodied mammals that also existed in North America, they vanished.
The cause of this mass extinction is unknown, and a number of theories exist. Though many factors were probably involved, a dramatic fluctuation in climate and perhaps the existence of prehistoric humans who may have relied upon these animals as a food source may have played a part in their disappearance.
Horses did not return to North America until the Spanish Conquistadors brought them from Europe in the late 1500's.
3.5 million years ago
Hagerman Horse exists
1.67 million years ago
Hagerman Horse evolves into Modern Horse
1 million years ago
Modern Horse exists
10,000 years ago
North American horse extinct
400 years ago
Spanish reintroduce horses
*Not to scale
Well Travelled Horse
Skeletons recovered here at Hagerman Fossil Beds National Monument have been, or currently are in the collection of such places as the Smithsonian Institution in Washington, D.C., the Carnegie Museum in Pittsburgh, the Field Museum in Chicago, the Musuem of Comparative Zoology at Harvard University, Denver Museum of Natural History, Royal Ontario Museum, Toronto, Texas Memorial Museum in Austin, and the Natural History Museum in Los Angeles County. Such exposures made this horse famous and in 1988 the state legislature made it the state fossil of Idaho.