Green River Formation fossils

Geologic context

The formation records ancient lake basins and surrounding environments. Fossil Butte National Monument protects an especially rich part of that record, including fish, reptiles, birds, mammals, insects, and plants. Material from a protected National Park Service unit is not commercial inventory; similar formation material offered legitimately may come from documented private quarries outside protected boundaries.

Identity and preparation

Common commercial labels include Knightia, Diplomystus, and other fish taxa. Ask what anatomical features support the identification. Inspect the slab edge, matrix texture, bone continuity, counterpart when available, repaired fractures, painted areas, and any transferred or composited material. A neat rectangular slab or dark outline is not proof of fabrication, but neither is it proof of originality.

Documents to request

• Named quarry or county-level locality and state.
• Land status and landowner or quarry record.
• Collector, collection date, and custody history where available.
• Preparation studio, repair map, added material, and restoration percentage.
• Dimensions measured on the fossil itself, not only the slab.

Value comparisons

Do not compare a common isolated fish with a multi-fish slab, rare taxon, articulated specimen, or extensively restored decorative piece. Jurassic Depot does not state unsupported price bands. Comparable evidence should match taxon confidence, completeness, size, preparation, restoration, locality documentation, date, and actual transaction type.