The Wyoming Green River Formation

During the Paleocene epoch which followed the great end Cretaceous catastophe, the present day Rocky Mountains began to fold and relentlessly push up the landscape that is now western North America.
By the beginning of the Eocene epoch which followed, lakes began to fill the basins between the mountain ranges. The Great Salt Lake in Utah is the last remnant of these ancient lakes. Two lakes, Fossil Lake and Lake Gosiute were in todays Wyoming and a third, Lake Uinta laid across Utah and Colorado. These lakes were likely linked at various times as fossils of the same creatures have been found in the sediments of each. The environment of the area was similar to present day Florida. Fossil pollen confirms the presence of luxuriant vegetation. Fossils of turtles and other amphibious reptiles further attest to the sub-tropical climate then existing.
The continued uplift of the Rockies provided abundant sources for the sediments which entombed and fossilized the creatures which lived in the lakes. Lake stratification which had well defined anoxic (low oxygen) layers below the upper well-oxygenated layer, coupled with the great sedimentation rate and carbonate precipitation, provided a near perfect environment for fossilization of the lake's inhabitants, great and small. This type of fossil environment is termed a lagerstätten.
At present, all our Green River Formation fossils are from the early Eocene Epoch Fossil Lake.
These 50 million year old fossils display well and will provide a unique gift, display, or conversation piece.