Fossilized Egg / Coprolite
Indeterminate vertebrate ichnofossil or oofossil cf. Dinosauria • Body fossil or trace fossil (likely vertebrate egg or coprolite)
Geological Period
Cretaceous
Estimated Age
66 to 145 million years
Preservation Type
Permineralization and complete lithification
Condition Assessment
Good condition; intact exterior contour with surface weathering and pitting, but lacking complete diagnostic shell microstructure visible to the naked eye
Taxonomic Classification
Vertebrata incertae sedis
Morphological Description
Ovoid, egg-like or nodular shape with a pitted, rough surface texture and faint concentric or linear weathering bands visible along the periphery.
Rock Matrix
Silicified or calcareous nodule matrix with fine-grained mineral infill
Formation & Location
Continental sedimentary deposits, historically found in regions such as the Two Medicine Formation (Montana) or equivalently aged red beds globally
Size & Dimensions
Approximately 5 to 8 cm in length, falling within the lower range of medium-sized dinosaur eggs or large coprolites
Value & Rarity
Estimated Market Value
$50 - $150 USD
Auction Estimate
$75 - $200 USD
Rarity Assessment
Uncommon as a well-defined suspected egg or coprolite, though morphologically ambiguous specimens are frequently encountered
Scientific Significance
Provides potential insights into ancient vertebrate reproduction, paleodiet, nesting behaviors, and terrestrial depositional environments
Preparation Recommendations
No aggressive mechanical preparation needed; optional surface cleaning with a soft brush and gentle consolidation if flaking occurs. Store in a stable, dry environment.
Notable Features
Distinctive ovoid geometry combined with a pitted, porous-appearing exterior texture and a pronounced circumferential band suggesting possible sedimentary compaction or layered accretion.