sedimentary

Fossilized Fish Skeleton in Matrix

Vertebrata (Class: Actinopterygii), typically found in limestone or shale matrices

AI-generated identification · may be incorrect

Hardness: 3-5 (calcite/apatite); Color: dark brown to black bones against tan or grey matrix; Luster: dull to sub-vitreous; Structure: biological skeletal preservation within a fine-grained sedimentary bed.

Hardness: 3-5 (calcite/apatite)
Color: dark brown to black bones against tan or grey matrix
Luster: dull to sub-vitreous

Identified April 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formation occurs through permineralization or carbonization where mineral-rich water replaces organic matter in an anaerobic environment; typical specimens are from the Eocene epoch (approx. 50 million years ago).

Uses & applications

Educational tools, museum displays, and private geological collecting. Highly valued for anatomical study of primordial life.

Geological facts

The Green River Formation in Wyoming is one of the world's most famous sites for such fossils, producing exceptionally detailed skeletons of fish like Diplomystus and Knightia.

Field identification & locations

Identified by symmetrical bilateral skeletal structures and articulated vertebrae embedded in flat sedimentary layers. Commonly found in quarries or basins known for fine-grained shale or limestone.