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Mioplosus labracoides, Green River, fossil fish

Mioplosus labracoides is an extinct perch-like fish with a long strongly built body. It was similar in appearance to living perch. Mioplosus 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 containing very well preserved fossils of fish, insects, plants, and other inhabitants of the area allow us to get an extremely good view of the environment of these ancient fresh water lakes.

The Green River Formation was formed by a system of three fresh water lakes which covered parts of Colorado, Utah, and Wyoming. The area covered by these lakes (Fossil, Gosiute, and Uinta) was about 25,000 squaare miles. The life spans for these three lakes was: over 17 million years for Lake Uinta, about 6 million for Lake Gosiute, and only about 2 million for Fossil Lake. The average deposition thickness for these three lakes is about 2,000 feet. The deposition depth at the center of Fossil Lake is about 200-260 feet thick. Lake Uinta deposition is in excess of 7,000 feet in places. The bulk of the fossil fish coming out of all three lakes is from Fossil Lake. Based on the types of flora and fauna found in the Green River Formation, it indicates that temperate to subtropical conditions existed, similar to the Gulf Coast of the United States.

Mioplosus was common in Fossil Lake, but rare in Lake Gosiute and Lake Uinta. As indicated by its pointed teeth, Mioplosus was a voracious predator. It frequently ate other fish up to half its own length. This can be verified by the many asphyxiation plates (Mioplosus died while trying to eat its dinner) that exist.

Mioplosus is one of the rarer and more sought after species from this location. Specimens of this size quality usually go for around $500.00 - $700.00, plus $150.00 for the frame.

10 inch fish in 15 x 11 inch frame.