Nice authentic fish fossil. The fossil is 53 mm long, on a 73 mm x 49 mm x 12 mm original stone matrix. About 50 million years old! Comes with a display stand. These 50 million year old, Eocene-Era fossil fish come from one of the world's famous Laggerstatten, the Green River Formation in Wyoming. A small portion of the fish fossils from Green River exhibits such fine preservation. The significant extent of soft-tissue preservation that makes the site famous is evident in these specimens. These particular fish are Knightia eocaena, the State Fossil of Wyoming. Knightia was a schooling fish that is sometimes found in mass mortality layers confined to a single plane, indicative of a single event. Theories as to the reasons include stratified water turnovers as well as poisoning due to blooms of blue-green algae. The modern-day Alewife is known to do so in the Great Lakes of the US. Shipping of this item is only as a Small Package.