• 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?

Fossil Butte from a distance

Fossil Butte National Monument preserves only 1% of the Fossil Lake deposits, the smallest of three ancient lakes that make up the famous Green River Formation.