Oyster Shell Fossil
cf. Gryphaea or Exogyra species • Body fossil, invertebrate marine bivalve
Geological Period
Jurassic to Cretaceous (Late Jurassic / Callovian to Oxfordian based on the Vaches Noires location)
Estimated Age
160 to 165 million years old
Preservation Type
Calcitic replacement and permineralization within a natural steinkern/matrix context
Condition Assessment
Good, somewhat weathered and water-worn surface from coastal action, largely intact single valve or incomplete internal mold
Taxonomic Classification
Phylum: Mollusca, Class: Bivalvia, Order: Ostreida, Family: Gryphaeidae, Genus: Gryphaea or Exogyra, Species: cf. Gryphaea arcuata or related ostreid
Morphological Description
Small, thick-shelled bivalve displaying prominent, coarse concentric growth folds and a distinctly curved or hooked umbo characteristic of pycnodont or gryphaeoid oysters. The surface shows weathered rugose ornamentation with alternating ridges and furrows.
Rock Matrix
Argillaceous limestone and calcareous marl typical of coastal cliff formations
Formation & Location
Falaises des Vaches Noires, Normandy, France (Callovian-Oxfordian formations)
Size & Dimensions
Approximately 25mm to 30mm in length, comparable to a standard 2 Euro coin (25.75mm diameter)
Value & Rarity
Estimated Market Value
5 to 15 USD
Auction Estimate
10 to 25 USD
Rarity Assessment
Common
Scientific Significance
Provides evidence of shallow marine Jurassic environments and ancient coastal shelf ecosystems along the northern European basins
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove residual clay; store in a dry environment
Notable Features
Collected from the famous Vaches Noires fossil-rich cliffs in Normandy, exhibiting characteristic thick oyster shell curvature
Notes
falaises des Vaches Noires