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The Green River formation offers a variety of fossil types. Following are some of the fossils that we find.

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Fossil Fish Cockerellites liops

Cockerellites liops is one of the more common fossils found in the Green River Formation. Until recently it was called Priscacara liops. Due to distinct differences between this fossil and Priscacara such as the larger number of dorsal fin rays, a thinner pelvic spine, and typically smaller in size, it has been re-classified Cockerellites. It was a schooling fish and is considered quite collectible due to its beautiful oval shape and pronounced dorsal fin. They likely preferred open water and would feed on insects and zooplankton. They are frequently found together in mass mortality layers. They average in length from 5" to 6".

Fossil Fish Cockerellites liops

Cockerellites liops is one of the more common fossils found in the Green River Formation. Until recently it was called Priscacara liops. Due to distinct differences between this fossil and Priscacara such as the larger number of dorsal fin rays, a thinner pelvic spine, and typically smaller in size, it has been re-classified Cockerellites. It was a schooling fish and is considered quite collectible due to its beautiful oval shape and pronounced dorsal fin. They likely preferred open water and would feed on insects and zooplankton. They are frequently found together in mass mortality layers. They average in length from 5" to 6".

Fossil Fish in Stone Priscacara serrata

The Priscacara is the fossil depicted in the Green River Stone logo. They are quite popular with collections due to their pleasing oval shape and well-defined dorsal fin. Priscacara serrata were large and had rounded, crushing teeth suggesting they ate shrimp and crayfish, and other mollusks. Normally they measure 5"- 8” while the larger specimens have been found over 14”.

Fossil Fish in Stone Priscacara serrata

The Priscacara is the fossil depicted in the Green River Stone logo. They are quite popular with collections due to their pleasing oval shape and well-defined dorsal fin. Priscacara serrata were large and had rounded, crushing teeth suggesting they ate shrimp and crayfish, and other mollusks. Normally they measure 5"- 8” while the larger specimens have been found over 14”.

Fossil Fish Diplomystus dentatus

The Diplomystus is one of the truly classic specimens from the Green River Formation. It was a surface feeder as can be seen from its sharply upturned jaw. An extinct genus of freshwater clupeoid the fossil was first named and described by Edward Drinker Cope in 1877. They commonly preyed on small fish such as Knightia and Priscacara. Their length will normally range from 5" - 8” but are also common in sizes from 16" - 20"

Fossil Fish Diplomystus dentatus

The Diplomystus is one of the truly classic specimens from the Green River Formation. It was a surface feeder as can be seen from its sharply upturned jaw. An extinct genus of freshwater clupeoid the fossil was first named and described by Edward Drinker Cope in 1877. They commonly preyed on small fish such as Knightia and Priscacara. Their length will normally range from 5" - 8” but are also common in sizes from 16" - 20"

Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils
Types of Fossils -  - About-Items - Green River Fossil Company

Fossil Fish
Knightia eocaena

Knightia are the most common fossils found in the Green River formation. They belong to the same taxonomic family as the herring and sardine. The Knightia was a secondary consumer, feeding mainly on algal forms and diatoms, as well as some smaller fish. They had heavy scales and small conical teeth. Knightia were schooling fish and because of this they are frequently found together in mass mortality layers. The average in length from 5" to 7"

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Fossil Fish Priscacara serrata

The Priscacara is the fossil depicted in the Green River Stone logo. They are quite popular with collections due to their pleasing oval shape and well-defined dorsal fin. Priscacara serrata were large and had rounded, crushing teeth suggesting they ate shrimp and crayfish, and other mollusks. Normally they measure 5"- 8” while the larger specimens have been found over 14”.

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Types of Fossils -  - About-Items - Green River Fossil Company

Fossil Fish Diplomystus dentatus

The Diplomystus is one of the truly classic specimens from the Green River Formation. It was a surface feeder as can be seen from its sharply upturned jaw. An extinct genus of freshwater clupeoid the fossil was first named and described by Edward Drinker Cope in 1877. They commonly preyed on small fish such as Knightia and Priscacara. Their length will normally range from 5" - 8" but are also common in sizes from 16" - 20"

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Types of Fossils -  - About-Items - Green River Fossil Company

Fossil Fish Mioplosus labracoides

The Mioplosus is an extinct genus of Percid fish that lived from the early to middle Eocene (38 to 56 million years ago).Mioplosus is the fish in our quarry that most resembles the modern day trout. They have pointed teeth and are believed to have been voracious predators. Mioplosus fossils are never found in large groups, which suggest they were solitary. Their length will normally range from 10" to 18".

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Fossil Fish Notogoneous osculus

The Notogoneous is considered a scarce fossil. It’s elongated body and ventrally located mouth were ideally suited for feeding on plants and decaying animals on the lake bottom. Few young have ever been found in Fossil Lake, suggesting that it spawned in streams and its fry developed there before moving to the deeper water of Fossil Lake. Their length is typically 18” to 25".

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Fossil Fish Phareodus encaustus, Phareodus testis

Phareodus is considered a scarce fossil. They are one of the more popular large fishes with collectors due to their large and impressive teeth and highly developed pectoral fins. The sharp teeth and sturdy build indicate that this fish was a piscavore (fish eater). In fact, remains of Mioplosus, Knightia, and Priscacara are often found in their stomaches. The smaller testis measure in length from 6" to 18” while the much larger encaustus grew to over two feet.

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Fossil Palm Mural Green River Formation

50 million years ago Fossil Lake was a subtropical climate akin to Florida today. The lake’s paleoenvironment persisted for about 2 million years, and was home to palm trees and many other plants. Unique conditions came together resulting in some of the best-preserved fossil plants ever discovered. Many of the plant specimens found in Fossil Lake are closely related to many modern species. For example palm fronds like the above: Sabalites powelli, are closely related to the modern sable palm.  Palm fossils are extremely rare and are among the most prized by collectors. This is likely due to their size and beautiful graphic shape. Palms can range in size from 3 feet to over 12 feet.

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Fossil Plants Plant Life Green river formation

The climate of Fossil Lake 50 million years ago was subtropical, similar to the climate of Florida today. The lake’s paleoenvironment persisted for about 2 million years, and was home to trees and many other plants. Unique conditions came together to result in some of the best-preserved fossil plants ever discovered. Plant specimens found in Fossil Lake are closely related to many modern species. Plant fossils include leaves, branches, flowers, seed pods, and other assorted flora.

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Fossil Fish Heliobatis radians

The stingray is usually found in seawater, but a few living freshwater species are known. They fed on the bottom in shallow water. Length up to 18".

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Fossil Fish Mural Gar - Lepisosteus simplex

Like living gar species, fossil gars were fish eaters. One adult species was so large, that perhaps only alligators and crocodiles preyed on it. This is the largest fish of the Green River Formation. Length normally 24" to 30".

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Turtle – Trionyx

Turtles are extremely rare in the Green River deposits. The turtle pictured was a soft shell Trionyx, similar to but much larger than modern species.

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Fossil Fish Aspiration Mural

An extremely rare occurrence, when a predatory fish ate prey that was too large to swallow and it became lodged in its throat.

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