Fossil Fish/Plant, Kemmerer, Wyoming
Knightia is an extinct genus of bony fish that lived in the fresh water lakes and rivers of North America and Asia during the Eocene epoch. Knightia belongs to the same taxonomic family as herring and sardines.
In Knightia fish, rows of dorsal and ventral scutes run from the back of the head to the medial fins. They had heavy scales, and small conical teeth. Their size varied by species: Knightia eocaena was the longest, growing up to 25 centimeters (10 inches), though most specimens are no larger than 15 centimeters. Knightia alta was shorter and relatively wider, with specimens averaging between 6 and 10 centimeters.
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of inter-mountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in the dry season. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years.