The mortality plate or grouping of fossil fish shows the large Mioplosus and Knightia, the smaller fish. The Mioplosus is a perch-like fish which can be distinguished by its two separate and distinct dorsal fins and fan-shaped tall. Its jaws were equipped with many small sharp teeth and its diet included small fish such as Knightia. From the Green River Formation, Fossil Lake, WY. Listed price is $260.00. Size is approximate 13 1/2" x 9 1/2" x 1/2" with a weight of 3 plus pounds. Fossils are brown on a creamy limestone. Large enough for a mantle piece. Dated at 40-60 million years old (Eocene Age) in excellent preservation after being cleaned and prepared.