Eocene Knightia Fossil Fish
Between 34 to 56 million years ago, during the Eocene Epoch, the subtropical climate in southwestern Wyoming supported life for numerous aquatic species in Lake Gosiute. As a thriving ecosystem with abundant marine plankton, the freshwater lake sustained herring shoals and varieties of predatory fish, stingrays, and crustaceans. Palm trees, crocodiles, and lizards also inhabited the area. One species of herring, the Knightia, is so plentiful that it later becomes the most common vertebrate fossil discovered anywhere the world. The factors were optimal for perfectly preserving mass amounts of Knightia in a large muddy lake bed with high concentrations of lime. Lake Gosiute, covering an area of fifteen thousand square miles, fluctuated in depth frequently and often exposed its lake bed to dry heat. Over time, sediment layers flattened under pressure and temperature swings to create large shale and soda ash deposits known collectively as the Green River Formation. Countless, well-pre...
