The fossil record preserved within the Eocene Green River Formation of Fossil Basin is world-renowned. Discoveries of new fossil species from the ancient lake sediments continue to expand understanding of the paleoecosystem.
The quality of fossil preservation is extraordinary, nearly unparalleled in the fossil record. The quiet-water, fine-grained lake sediments, and water conditions that excluded scavengers combined to preserve articulated skeletons (all bones are in place rather than scattered). Delicate fossils, rarely preserved elsewhere, yield valuable scientific data.
Today less than 1% of Fossil Lake is protected and managed by the National Park Service. Fossil Butte National Monument is a site that promotes the protection of this world-class paleontological heritage.
Check out the fossil and donated fossil photo galleries and find more information about the various fossil species of the Fossil Butte Member (FBM) below.
If you want to see the data from the fossils collected in the park's research quarry, download the Fossil Lake Quarry Data Spreadsheet (Excel 0.25 MB). If you do not see recent data, check back as the document is updated periodically.
Last updated: May 4, 2022