Fossil Butte National Monument
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![Heliobatis radians, an extinct stingray, had small teeth for crushing snails and other mollusks and barbed spines on the tail for defense. This specimen is about 35 centimetres (14 in) long, including the tail.](/Images/godic/202501/14/Heliobatis_radians_Green_River_Formation2243.jpg")
![This 1.7 meter (5 foot 6 inch) Trionychid softshell turtle is one of the largest turtles known from Fossil Lake.](/Images/godic/202501/14/Trionychidae_FBNM2243.jpg")
Fossil Butte National Monument is a United States National Monument managed by the National Park Service, located 15 miles (24 km) west of Kemmerer, Wyoming, USA. It centers on an extraordinary assemblage of Eocene Epoch (56 to 34 million years ago) animal and plant fossils associated with the smallest lake — Fossil Lake — of the three great lakes which were present at that time in what are now Wyoming, Utah, and Colorado. The other two were lakes were Lake Gosiute and Lake Uinta. Fossil Butte National Monument was established as a national monument on October 23, 1972.