4.55" Fossil Fish (Cockerellites) - Green River Formation

This is an exceptionally well preserved, 4.55" long Cockerellites (Priscacara) liops fish from the famous 18 inch layer of the Green River Formation. It was collected from Lindgren Quarry near Kemmerer, Wyoming. It is beautifully centered on a rectangular slab of rock.

This specimen includes an acrylic display stand.

Priscacara is an extinct genus of perch from the Eocene (55.8-33.8 mya) Fossils of these fish are commonly found in the Green River Formation in Wyoming. Priscacara probably darted about freshwater streams and lakes, snatching at small creatures like snails, crabs, prawns, and tadpoles.

They varied in size; for example, P. liops is a smaller species, never exceeding 150 mm, whereas the larger P. serrata has been found up to 375 mm. Priscacara means, “Primitive head”. These tough looking, ray-finned fish packed a punch if something dared to swallow it. The genus is known for its protective dorsal and anal spines.

50 million years ago, Priscacara thrived in lakes fed by Uinta and Rocky Mtn. highlands. This plucky genus of perch, possibly related to modern-day Cichlids, is now entombed in the fine-grained, lime mud of Fossil Lake. Priscacara eventually went extinct by the end of cooler and drier Miocene (23-5.2 mya).

Today the wonderfully-preserved fossils of Priscacara and other Fossil Lake fauna are collected in several private quarries around Kemmerer, Wyoming. The best preserved fish fossils come from the coveted 18 inch layer. This layer is collected at night under high-powered lights allowing the faint signs of fish under the surface to be more easily observed. These “ghosted” fish then must go through many hours of manual preparation to remove the overlying rock and reveal the Green River fauna in all of its glory.

It comes from the coveted 18 inch layer of the Green River Formation which produces darker and more detailed fish than the majority on the market. The rock from this layer is much harder and more durable. This layer is typically collected at night using low-angle light to see the bump in the rock that the backbone creates. They then cut these fish out and take them to a lab where the fish, which may be up to an inch under the surface of the rock, are meticulously extracted under microscope with hand tools.

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.

50 million years ago, in the Eocene these fish thrived in Fossil Lake fed by Uinta and Rocky Mountain highlands. The anoxic conditions at the bottom of Fossil Lake slowed bacterial decomposition, prevented scavengers from disturbing corpses, and most interestingly, suffocated creatures that ventured into the oxygen-starved aquatic layer. The result is a miraculous exhibition of Eocene biota in a subtropical, aquatic community within sycamore forests teeming with creatures such as freshwater stingrays, dog-sized horses, menacing alligators, early flying bats, and one of the first primates.

A view of one of the commercial quarries where fossils from the Green River Formation are collected.
A view of one of the commercial quarries where fossils from the Green River Formation are collected.
FOR SALE
$265
DETAILS
SPECIES
Cockerellites (Priscacara) liops
LOCATION
Lindgren Quarry, Kemmerer, Wyoming
FORMATION
Green River Formation, 18 Inch Layer
SIZE
4.55" long on 9.1 x 8.5" rock
CATEGORY
ITEM
#179243
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