Fossil Palm Frond

A COMPLETE, INTACT, AND WELL-PRESERVED PALM FROND FROM WYOMING'S GREEN RIVER FORMATION

50 million years ago, the Green River Formation comprised an area of more than 25,000 square miles (65,000 sq. km) of interconnected subtropical lakes spread across the current states of Wyoming, Utah, and Colorado. Today, the region of the Green River Formation known as "Fossil Lake" boasts some of the most abundant and well-preserved freshwater fossils anywhere in the world.

Not only does plant material rarely fossilize, but finding plant fossils in Fossil Lake is particularly challenging because they rarely have any thickness to detect during excavation. Thus, the only way a plant such as a palm frond is discovered is when a layer of rock is fortuitously split in just the right place, or if it is exposed in the laboratory as another fossil is being prepared. Because of the size and level of preservation of the palm frond found here, it is likely that it came from an ancient palm grove very close to the shore of Fossil Lake.