Eocene Green River Notogoneus
Notogoneus osculus with Knightia eocaena
Green River Fm (Middle Eocene)
Lincoln County, Wyoming
This specimen is a very perfectly preserved Notogoneus from our Green River collection. It is from just below the 18 inch layer from a kerogen-rich zone noted for exceptional preservation. The specimen has a dramatic arched pose and the front quadrant is twisted and presents a dorsal aspect. Both pectoral fins are clearly visible. The Notogoneus skeleton is 21 inches long. An added feature is the beautiful Knightia that is 5.75 inches long. The slab is repaired and the only restoration is along the repaired fracture. Overall the slab is 30 inches by 17 inches.

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 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.
Genus Notogoneus is one of the more uncommon taxa offered from the Green River Formation, and with a maximum total length of 91 cm, one of the largest. The Gonorynchidae are a marine family of fishes commonly called �sand fish� which are found today in the near-shore regions of the Indo-Pacific.