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A composite fossil is two or more specimens assembled to look like one. One of the hardest frauds to detect — and one of the most common.
Sellers must: Disclose composite percentage, mark listing as composite, explain which parts are from different specimens.
Penalty for non-disclosure: Listing removal, seller suspension, permanent ban for repeat violations. Full buyer refund.
Expert review required: Any listing with composite > 0% requires pre-listing restoration review. Composite > 20% requires admin approval.
Restoration
Repairing one specimen's breaks. Normal and expected.
Composite
Parts from different specimens combined. Must be disclosed.
Fraud
Composite sold as one specimen without disclosure.
Trilobites
Most commonly composited fossil. Real body with fake spines, fake thorax, or head/tail from different specimens. Moroccan trilobites especially risky.
Mosasaur Jaws
Real teeth set into fabricated jawbone of plaster and glue. Teeth may be genuine — the jaw is an art project. Extremely common from Morocco.
Dinosaur Skeletons
Bones from multiple individuals or species assembled as one. May include cast parts, sculpted bones, and bones from different formations. Demand bone-by-bone docs.
Crinoids
Stems from different specimens glued to a slab for dramatic display. Stems may be real — arrangement is fabricated.
Dinosaur Teeth
Crown from one specimen attached to root from another. Genuine tip with fabricated base. Common in large theropod teeth.
UV Light (365nm): Best composite detection tool. Different materials fluoresce differently. Glue and fill light up while genuine material appears uniform.
Color Matching: Different specimens have different matrix colors, mineral staining, patina. Subtle differences = red flag.
Texture Comparison: Bone surface detail, matrix grain size, wear patterns should be consistent. Inconsistency across specimen = likely composite.
X-Ray / CT: Density changes at composite joins. Different radiodensity signatures for bone vs plaster vs resin.
Microscopy: Genuine cracks look different from saw cuts or glued surfaces at 20x-60x.
Chemical Testing: Acetone and solvents reveal glue lines, paint, fill. Small samples identify different matrix compositions.
0% composite: No disclosure needed. Standard review.
1-10%: Must disclose. Expert pre-listing review badge recommended.
10-20%: Expert restoration review required. Mandatory disclosure. Label parts in photos.
20%+: Admin review + expert review required. Full breakdown. "Composite Specimen" label.
Undisclosed: Listing removed. Seller account review. Buyer refund. Repeat = suspension.