Dinosaur Coprolite (Petrified Dung)
Incertae sedis (unidentified dinosaurian or archosaurian producer); cf. Coprolithes sp. • Trace fossil (ichnofossil), permineralized excrement
Geological Period
Jurassic to Cretaceous
Estimated Age
150 to 66 million years
Preservation Type
Permineralization; biological matter replaced by silica (agate/jasper) or iron minerals (hematite/limonite), preserving the external structure and internal voids.
Condition Assessment
Good/Fair; stable and well-mineralized but fragmented, lacking the complete cylindrical or spiral morphology found in premium specimens.
Taxonomic Classification
Ichnogenus: Likely cf. Coprolithes; Kingdom: Animalia; Chordata; Reptilia; Dinosauria
Morphological Description
Irregularly shaped, bulbous mass with a distinctive 'cackly' or convoluted surface texture. Features rugose longitudinal cracks, visible inclusions that may represent undigested organic matter, and a lack of symmetry typical of fossilized fecal matter.
Rock Matrix
Reddish-brown iron-rich siltstone or claystone matrix; likely contains secondary replacement minerals such as hematite or siderite.
Formation & Location
Morrison Formation (USA), Hell Creek Formation (USA), or equivalent Mesozoic terrestrial sediments in Madagascar or North Africa.
Size & Dimensions
Approximately 5-8 cm in diameter; consistent with medium-sized herbivorous or omnivorous dinosaurian producers.
Value & Rarity
Estimated Market Value
$25 - $65 USD
Auction Estimate
$30 - $50 USD
Rarity Assessment
Common; coprolites are widely distributed in Mesozoic terrestrial deposits, though specific identifiable 'high-texture' pieces are more desirable.
Scientific Significance
Provides critical data on ancient diets (paleodietary analysis), metabolic rates, and the composition of the gut microbiome in extinct archosaurs.
Preparation Recommendations
Keep in a low-humidity environment to prevent oxidation of iron minerals; clean with a dry soft brush; optional cross-sectioning and polishing can reveal internal inclusions.
Notable Features
Distinctive ferruginous (iron-rich) staining and deep surface desiccation cracks that occurred prior to burial and mineralization.