Phareodus belongs to the osteoglossids which are represented today by the Arawana. Arawana are found in tropical and semitropical fresh waters of South America, central Africa, Southeast Asia, and northern Australia. Phareodus means: phare-to have, odus-tooth. Phareodus lived during the Eocene Epoch and is about 55 million years old. They can be found in the fine grained limestone layers of the world famous Green River Formation. These fine grained layers of limestone contain very well preserved fossils of fish, insects, plants, and other inhabitants of the area which allow us to get an extremely good view of the environment of these ancient fresh water lakes. Phareodus was more common in Fossil Lake and rarely occurs in Lake Gosiute and Lake Uinta. As indicated by its name, Phareodus testis was a voracious predator. Spines from Mioplosus and Priscacara are frequently found in the stomachs of Phareodus, as further evidence. Maximum size for Phareodus testis was about 15 inches. Body depth was about 43-52% of its length. The jaws of Phareodus testis are smaller with fewer teeth than Phareodus encaustus. The gill plate cover is slightly larger in Phareodus testis. The pectoral fin ray is 20-30%, or more, of the body length (longer for adults). Scales of Phareodus testis are larger and fewer than the scales of Pharoedus encaustus. Dimensions: 15" x 12-1/2" x 1"