Description
Rare Cockerellites liops Fossil Fish from the Green River Formation
This exceptional Cockerellites (Priscacara) liops fossil fish originates from the renowned Fossil Butte Member of the Green River Formation near Kemmerer, Wyoming, USA. The Green River Formation is one of the most famous fossil lagerstätten in the world, celebrated for its remarkable preservation of freshwater fish and other organisms from the Eocene Epoch, approximately 56 to 34 million years ago.
Cockerellites liops is considered one of the more desirable fish fossils from this formation due to its distinctive body shape, detailed skeletal preservation, and relative rarity compared with more commonly found species such as Knightia. The specimen has been carefully selected for quality and display, showing the natural fossil preserved within fine-grained sedimentary rock typical of the Fossil Butte Member.
The photographs provided show the exact fossil specimen you will receive, allowing collectors to observe the skeletal structure and preservation before purchase. Full sizing can be clearly seen in the listing photos.
This fossil is a genuine specimen and includes a fully hand-signed Premium Certificate of Authenticity, confirming its authenticity and geological origin.
Fossil Identification and Scientific Classification
The species Cockerellites liops was originally described by the American palaeontologist Edward Drinker Cope in the late 19th century. The species was previously placed in the genus Priscacara, and many specimens are still referred to by this earlier classification.
Scientific classification includes:
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Perciformes
- Family: Priscacaridae
- Genus: Cockerellites
- Species: Cockerellites liops
Members of the Priscacaridae family are extinct freshwater fish that inhabited ancient lakes during the Eocene. These fish are characterised by a laterally compressed body, spiny dorsal fins, and strong skeletal structure.
Geological Age and Stratigraphy
This fossil originates from the Fossil Butte Member of the Green River Formation, which represents sediments deposited during the Eocene Epoch. The Fossil Butte Member specifically formed within Fossil Lake, one of several large freshwater lakes that existed in the region during this time.
The Green River Formation consists primarily of:
- Laminated limestone
- Fine-grained carbonate mudstone
- Oil shale deposits
These sediments accumulated in calm lake environments where fine particles settled slowly on the lakebed, creating ideal conditions for preserving delicate organisms such as fish, insects, and plants.
Morphology and Anatomical Characteristics
Cockerellites liops displays a number of distinctive morphological features that distinguish it from other fish fossils found in the Green River Formation.
Typical anatomical characteristics include:
- Deep-bodied, laterally compressed fish shape
- Prominent spiny dorsal fin
- Large eye sockets
- Well-defined vertebral column
- Strong pectoral and pelvic fin structures
The species typically displays a relatively compact body form with a large head and strong fin spines, features associated with perch-like fish.
In well-preserved specimens, collectors can often observe:
- Individual fin rays
- Vertebrae and rib structures
- Cranial bones
- Scale impressions
The preservation quality of Green River fossils frequently allows fine skeletal details to remain visible.
Depositional Environment of Fossil Lake
During the Eocene, the region around present-day Wyoming was covered by a series of large freshwater lakes, including Fossil Lake, Lake Gosiute, and Lake Uinta. Fossil Lake, where the Fossil Butte Member formed, was a relatively small but deep lake that supported a diverse aquatic ecosystem.
The environment included:
- Calm freshwater lake waters
- Seasonal climatic cycles
- Periods of low oxygen near the lake bottom
- Fine sediment deposition
Low oxygen conditions at the lakebed limited scavenging and decomposition, allowing fish and other organisms to settle intact into the sediment and become fossilised.
Fossil Preservation in the Green River Formation
The Green River Formation is renowned for its exceptionally fine fossil preservation. Thin layers of limestone accumulated gradually on the lake floor, capturing organisms with remarkable detail.
Fish fossils such as Cockerellites liops are typically preserved in thin laminated limestone slabs, often displaying articulated skeletons where the bones remain in life position.
This level of preservation allows palaeontologists and collectors to study anatomical structures in detail and provides an extraordinary window into Eocene freshwater ecosystems.
Collecting and Scientific Importance
Cockerellites liops fossils are highly sought after by collectors due to their distinctive appearance and relative rarity compared to other Green River fish species. The Green River Formation has been studied for over a century and remains one of the most significant fossil sites for understanding ancient freshwater ecosystems.
Collectors appreciate these fossils for several reasons:
- Classic Green River Formation fossil locality
- Detailed skeletal preservation
- Distinctive deep-bodied fish morphology
- Historical importance in palaeontological research
Specimens are often displayed in fossil collections, natural history exhibits, and geological teaching collections.
Authentic Fossil Specimen
This specimen is a genuine Cockerellites (Priscacara) liops fossil fish from the Fossil Butte Member of the Green River Formation in Kemmerer, Wyoming, USA, selected for preservation and display quality.
Key details include:
- Authentic fossil fish specimen
- Species: Cockerellites liops
- Formation: Green River Formation
- Member: Fossil Butte Member
- Age: Eocene Epoch
- Locality: Kemmerer, Wyoming, USA
- Classic Green River fish fossil preserved in limestone
- Exact fossil shown in listing photographs
- Full sizing visible in listing images
- Includes fully hand-signed Premium Certificate of Authenticity
This remarkable fossil represents a preserved snapshot of Eocene freshwater life within the ancient lakes of North America, making it a highly desirable addition to fossil collections and natural history displays.
Reviews
There are no reviews yet.