The Scenario

This scene depicts the subtropical forest surrounding the Green River Lake system, in what is now southwestern Wyoming. The forest is composed of deciduous hardwood trees, as well as palms and early cacti. In the higher mountains surrounding the lakes, the forest contains mixed conifers and deciduous hardwood trees. These lush surroundings supported a diverse fauna of mammals, both on the ground and in the trees, including early relatives of living rodents, lemurs, and horses.

The Environment

The climate was relatively warm, and rainfall was high, although it showed variation with the seasons. The summer months were the driest part of the year. In the basin, freezing temperatures were unheard of, judging by the presence of animals like crocodiles, but cool winter temperatures and frost may have been present at higher elevations.