Knightia Fossil Fish
Knightia eocaena • Body fossil (compression); Vertebrate
Geological Period
Eocene Epoch (Paleogene Period)
Estimated Age
Approx. 48 to 52 million years old
Preservation Type
Carbonization and replacement; mineral-rich organic compression with fine skeletal detail.
Condition Assessment
Very Good. The skeleton is mostly articulated, though some minor scales are scattered; the skull and eye socket show high contrast.
Taxonomic Classification
Phylum: Chordata, Class: Actinopterygii, Order: Ellimmichthyiformes, Family: Paraclupeidae, Genus: Knightia
Morphological Description
Small, herring-like fish with a deep, fusiform body. Notable features include a prominent dorsal fin, a deeply forked homocercal tail (caudal fin), and well-preserved vertebral columns. Row of ventral scutes along the belly and large orbital sockets are clearly visible.
Rock Matrix
Fine-grained, laminated lacustrine limestone (oil shale) from a freshwater lake bed.
Formation & Location
Green River Formation; Wyoming, USA (specifically Kemmerer or Fossil Butte regions).
Size & Dimensions
Approximately 10-12 cm in length, which is a typical adult size for this genus.
Value & Rarity
Estimated Market Value
$50 - $125 USD
Auction Estimate
$40 - $100 USD
Rarity Assessment
Common; Knightia is the state fossil of Wyoming and is found in high abundance in the '18-inch layer' and 'split-fish layer'.
Scientific Significance
Knightia is crucial for understanding the paleoecology of the Eocene Great Lake system. It served as a primary food source for larger predators and provides data on seasonal mortality events and mass schooling behavior.
Preparation Recommendations
Should be kept in a dry environment. Clean only with a soft brush; do not use water. Mounting on a stand or framing is recommended due to the fragility of the shale edges.
Notable Features
Excellent dark brown contrast against the buff-colored matrix. The distinct preservation of the pelvic and pectoral fins makes it a classic decorative and educational specimen.