• Knightia eocaena mass mortality

    Fossil Butte

    National Monument Wyoming


Short-horned lizards are well camouflaged.

Mountain short-horned lizard

NPS photo

The wandering garter snake (Thamnophis elegans vagrans) and short-horned lizard (Phrynosoma douglassi brevirostre)are the only reptiles documented.

The monument's sagebrush steppe landscape appears ideal habitat for rattlesnakes, but they are not found here. Why? We don't know. Prairie rattlesnakes inhabit other parts of Wyoming at elevations over 8500 feet, but usually are restricted to elevations less than 7,000 feet.

Did You Know?

Diplomystus dentatus, NPS photo of Fossil Country Museum specimen

Railroad workers played a major role in the discovery of fossils from the Green River Formation. In the late 1860's, Union Pacific workers uncovered the first major fossil fish beds (Lake Gosiute) near the town of Green River, Wyoming.