Hagerman Fossil Beds
Idaho
About forty miles west of Twin Falls along the Snake River, the canyon walls expose something extraordinary: one of the richest deposits of Pliocene-era fossils in North America. The Hagerman Fossil Beds, now a National Monument, preserve animals from approximately three point five million years ago, when this part of Idaho was a warm, wet landscape of marshes and open woodlands. The most famous resident is the Hagerman Horse, an early equid that resembles a modern zebra more than a horse and is one of the oldest known members of the horse genus in North America.
More than two hundred specimens have been excavated from a single bluff. The beds also contain mastodons, giant ground sloths, saber-toothed cats, and peccaries. A rancher named Elmer Cook first noticed the bones eroding from the bluff, and in nineteen twenty-eight he showed them to a government geologist.
The Smithsonian Institution sent an expedition the following year and began what became one of the most productive paleontological digs in the West. The monument today protects about four thousand four hundred acres of Snake River canyon land.
