Carboniferous ironstone concretions preserve plants, invertebrates, fish, and rare soft-bodied organisms.
RegionIllinois, USA
Best recordFormation + source
Risk controlLegality + disclosure
Commonly associated fossils
- ferns and seed ferns
- jellyfish and worms
- arthropods
- fish and amphibian material
Collector cautions
- part and counterpart add confidence
- avoid over-splitting fragile concretions
- document legal access and exact nodule provenance
Provenance questions
- What is the most precise locality that can be responsibly shared?
- What formation, member, quarry, or horizon is claimed?
- Who collected it, when, and on what type of land?
- Was export documentation required, and does paperwork accompany the specimen?
- What preparation, stabilization, repair, or assembly occurred after collection?
Why locality affects identification
Fossil groups have geographic and stratigraphic ranges. Matrix, preservation style, associated fauna, and preparation traditions can support or contradict a locality claim. A famous locality name should never substitute for documentation.
Build a comparison set
Use listings to compare morphology, matrix, preparation, locality claims, dimensions, repairs, and seller disclosure. Similar appearance alone does not establish identity or legality.
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