This small fish, Knightia, was an important food source in the freshwater lakes that dotted Wyoming 50 million years ago in the Eocene. Occasionally fossils have been found with Knightia trapped in the jaws or stomach of larger predatory fish like the Diplomystus or Mioplosus. In the green river formation, plates with schools of Knightia have been found. It is classified in the Clupeidae family which includes present-day herrings. It is 5 1/2 inches by 4 inches.