Fossil Butte National Monument

Fossil Butte National Monument preserves the best paleontological record of Cenozoic aquatic communities in North America and possibly the world, within the 50-million-year-old Green River Formation — the ancient lake bed.

Fossils preserved include fish, alligators, bats, turtles, a dog-sized horse, insects, and many other species of plants and animals — suggest that the region was a low, subtropical, freshwater basin when the sediments accumulated, over about a 2 million-year period.

Summer activities also include ranger programs, hikes, paleontology and geology talks, and participation in fossil quarry collections for the park.

A highlight is hiking 3/4 mile up the butte to the dig, where interns from the Geological Society of America talk about their excavation and let children help them flake apart sedimentary deposits to discover fish fossils and coprolites.

Fish: Amphibians: Mammals: Birds: Reptiles: Plants: Arthropods: Primary source:[9] Other NPS Cenozoic Era sites in the western U.S.:

Map of major Wyoming geological formations, showing Fossil Butte (lower left) far south of Yellowstone (upper left), southwest across the state from Devils Tower (upper right).
This 1.7-meter (5 foot 6 inch) Axestemys byssinus is one of the largest turtles known from Fossil Lake.
Stingray prepared by R. Lee Craig ( Asterotrygon maloneyi ). In the collection of Fossil Shack. Prepared circa 1920.
† Chaneya tenuis