Ammonite (Partial Whorl Imprint/Cast)
cf. Perisphinctes sp. or cf. Hoplites sp. • Body Fossil / External Mold / Cast (Invertebrate Mollusk)
Geological Period
Jurassic to Early Cretaceous (likely Lower Cretaceous or Upper Jurassic based on European regional context)
Estimated Age
100 - 160 million years
Preservation Type
Recrystallization / Mold and Cast preservation in a fine-grained calcareous matrix.
Condition Assessment
Fair - Partial specimen embedded in matrix, showing clear ribbing on the visible fragment but missing the majority of the shell, aperture, and phragmocone.
Taxonomic Classification
Phylum: Mollusca, Class: Cephalopoda, Subclass: Ammonoidea, Order: Ammonitida
Morphological Description
Exhibits a section of an ammonite shell whorl preserved in relief showing distinct, closely spaced transverse ribs (costae). The ribs are slightly curved and pronounced along the outer flank of the whorl segment.
Rock Matrix
Light beige to greyish marly limestone/chalky matrix typical of marine sedimentary rocks.
Formation & Location
Common in Mesozoic marine limestone and marl formations across Europe (e.g., France, UK, Southern Germany).
Size & Dimensions
The visible ammonite fragment is approximately 3 to 5 cm in length, embedded within a rock matrix piece measuring roughly 10-12 cm wide.
Value & Rarity
Estimated Market Value
$15 - $35 USD
Auction Estimate
$20 - $40 USD
Rarity Assessment
Common (Ammonite fragments in limestone matrix are widely distributed in Mesozoic strata).
Scientific Significance
Ammonites are key index fossils used for biostratigraphy to date marine Mesozoic strata and reconstruct ancient marine environments.
Preparation Recommendations
Mechanical air-scribe preparation could potentially reveal more of the whorl if preserved deeper within the matrix. Keep in a dry, stable indoor environment away from acidic chemicals.
Notable Features
Sharp, prominent rib ornamentation on the exposed whorl section, contrasting nicely with the fine-grained light limestone matrix.