18" Multiple Fossil Fish (Priscacara & Diplomystus) Plate - Wyoming

This is a 18" wide fossil fish plate collected from Lindgren Quarry at the Green River Formation of Wyoming. The shale contains a (Priscacara serrata and a Diplomystus dentatus) fish that are naturally associated with each other and bear red-brown preservation. The Priscacara is 8" long and the Diplomystus measures 7.1" long.

This specimen is accompanied by a display stand, however upon request we can add a backing and wall mounting hardware.

About Diplomystus

Diplomystus is an extinct genus of freshwater, ray-finned predators that are distantly related to modern herrings and sardines. Diplomystus has a distinctive jaw that protrudes aggressively outward from the mouth at an angle that allowed it to feed in surface waters and devour such prey as the smaller, schooling Knightia.

50 million years ago in the Eocene (55.8 mya to 33.8 mya), D. dentatus thrived in lakes fed by the Uinta and Rocky Mountain highlands. D. dentatus is uniquely entombed in the fine-grained lime mud of Fossil Lake.

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.

By the end of the Eocene, Earth developed icehouse climate characteristics and had a change in atmospheric chemistry. The effects of bolide impacts may also have contributed to the eventual loss of flora and fauna at once verdant latitudes.

Today the wonderfully preserved fossils of Diplomystus 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, enhancing the faint signs of fish under the surface indicating underlying fossils. 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.

Priscacara is an extinct genus of temperate bass that lived during the Eocene. It is an uncommon species in the Green River Formation, representing less than 1 percent of total fish fossils. It is a favorite among fossil collectors, particularly those specimens with all of their dorsal spines pointing upwards. It can occasionally reach impressive sizes in excess of 16 inches in length. Priscacara has a large mouth and impressive array of teeth can often be seen in detail on larger, well-preserved specimens.

Priscacara is more frequently found in shoreline lake deposits and less frequently found in rocks deposited in the center of the lake. Its appearance is very similar to that of Cockerellites, a genus of smaller schooling fish found in large numbers in the mid-lake quarries. Cockerellites maxed out in the 5 to 6-inch range, so specimens larger than that are assumed to be Priscacara. Cockerellites have more dorsal and anal fin rays than Priscacara and a significantly smaller mouth.

About The 18 Inch Layer Of Fossil Lake

Specimens like this come 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 than other layers in the formation, likely due to its initial deposition conditions in deep water. Because of these conditions, fish found in the 18-inch layer can be extracted whole and in excellent condition. This layer is typically collected at night using low-angle light to see the bump in the rock that the fish's 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.

About Fossil Lake

50 million years ago, in the Eocene epoch, these fish thrived in Fossil Lake, which was fed by the 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: 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.
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DETAILS
SPECIES
Priscacara serrata & Diplomystus dentatus
LOCATION
Lindgren Quarry, Kemmerer, Wyoming
FORMATION
Green River Formation - 18 Inch Layer
SIZE
Priscacara: 8" wide, Shale: 18 x 12.3"
CATEGORY
ITEM
#275196
GUARANTEE
We guarantee the authenticity of all of our specimens.