13" Fossil Fish (Phareodus) - Green River Formation, 18 Inch Layer

This is a darkly preserved, 13" long Phareodus from the famous 18 inch layer of the Green River Formation in Wyoming. It's nicely centered on an unbroken 16.6 x 9.9" slab of shale, and the preservation is dark and detailed. This specimen is backed with plywood and includes a strap hanger for easy hanging.

About The 18 Inch Layer Of Fossil Lake

Specimens of this quality come from the coveted 18-inch layer of the Green River Formation, a horizon renowned for producing exceptionally dark, detailed, and well-preserved fossil fish. The limestone from this layer is significantly harder and more durable than that found in many other parts of the formation, likely a result of the deep-water conditions under which it was originally deposited.

These conditions helped preserve fish in remarkable completeness, allowing exceptional specimens to be recovered largely intact. Locating them is a specialized process. The layer is often worked at night using low-angle lighting, which reveals the subtle raised contours created by a fossil fish—particularly the backbone—hidden beneath the surface of the limestone.

A view of the 18 inch layer of the Green River Formation at the Lindgren quarry near Kemmerer, Wyoming.
A view of the 18 inch layer of the Green River Formation at the Lindgren quarry near Kemmerer, Wyoming.


Once identified, the surrounding rock is carefully cut away and the specimen is transported to a preparation laboratory. Because the fossil may lie as much as an inch beneath the surface, exposing it requires painstaking work under magnification. Skilled preparators use fine hand tools to gradually remove the overlying limestone, revealing the fossil in extraordinary detail while preserving the delicate bones beneath.

SOLD
DETAILS
SPECIES
Phareodus testis
LOCATION
Kemmerer, Wyoming
FORMATION
Green River Formation, 18 Inch Layer
SIZE
13" fish on 16.6 x 9.9" shale
CATEGORY
ITEM
#114330
GUARANTEE
We guarantee the authenticity of all of our specimens.