Notogoneus osculus Green River Fm (Middle Eocene) Lincoln County, Wyoming
This specimen is the most perfectly preserved Notogoneus from our many years of collecting Green River fossils. The fish is 9 inches long and the overall plate measures 10 x 14 inches It is from the 18-inch layer and is not as large as most that are found. There is no restoration.
In the Green River Formation this family of fishes is represented by this single genus and species. It was the last surviving member of the order Gonorynchiformes in North America. It has an elongate body and a head that has ventrally located, toothless mouthparts suited for bottom feeding. Notogoneus is not nearly as common as Diplomystus or Knightia in the formation. They are found more abundantly in the deeper facies of the ancient Green River Lake deposit.
