Florissant Formation

The Florissant Fossil Formation is a lagerstätte in the Colarado part of the Rocky Mountains. It shows life in the Eocene in as-yet unraised part of what is now the Rocky Mountains. It shows the whole forest ecosystem in some detail, particularly the plants. From this we can be sure the forest was sub-tropical, and the climate much warmer than today.
This site shows the scene right at the end of the long Eocene period. The fauna is discussed in a well-illustrated book. The site is protected as the Florissant Fossil Beds National Monument.