Diplomystus dentatus are an extinct genus of prehistoric fish from the Eocene period. Previously placed in the herring family, they have been recategorised in the herring-like family Ellimmichthyidae. These predatory fish consumed smaller occupants of the Green River Formation, such as Knightia, which can sometimes be found lodged in the throats of Diplomystus fossils. Only one described species of this genus has been found in the Green River Formation so far, but three other species have been identified elsewhere, in Japan and Korea. Specimens can range from larval size to up to 65 cm.
Fossilised Diplomystus Dentatus Specimen
A well-preserved specimen of Diploymystus dentatus, embedded in stone and framed. The strongly upturned mouth can be made out clearly, and indicates that Diplomystus fed in the open water rather than from the river bed. This specimen is from the area known as Fossil Lake in the Green River Formation, in south-west Wyoming, where the very fine-grained lime muds have preserved a high number of fossils. This is a large specimen.
Period: Eocene Period
Condition: Good condition, in modern frame.