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