Fossil Lake existed 52 million years ago in what is now southwest Wyoming. Today its sediments contain one of the richest fossil deposits in the world. Preserved in limestone are abundant fish and other organisms of the aquatic ecosystem including: plants, alligators, crocodiles, turtles, insects and crayfish. Less common are fossils from environments that surrounded the lake such as a horse, bats, lizards, birds, leaves, flowers and insects. The fossils indicate a warm and wet climate, quite different from the high, cold desert of southwest Wyoming today.