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Fossil Butte

The site preserves the best paleontological record of Tertiary aquatic communities in North America and possibly the world, within the 50-million-year-old Green River lake beds. Fossils preserved, including fish, alligators, bats, turtles, dog-sized horses, 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.