Oyster or Exogyra fossil
Exogyra cf. virgula or similar pycnodontine oyster • Body fossil, invertebrate
Geological Period
Jurassic to Cretaceous (specifically Late Jurassic to Late Cretaceous based on the Vaches Noires location)
Estimated Age
165 to 85 million years ago
Preservation Type
Original calcitic shell material preserved with some surface weathering and matrix adherence
Condition Assessment
Good condition, moderately weathered but largely intact with visible surface ornamentation and characteristic shape
Taxonomic Classification
Phylum Mollusca, Class Bivalvia, Order Ostreida, Family Gryphaeidae
Morphological Description
Small, highly inequivalve bivalve with a strongly curved or coiled umbo characteristic of pycnodont oysters, displaying coarse ribbed ornamentation on the exterior surface.
Rock Matrix
Marl and clay-rich sedimentary matrix characteristic of the coastal cliffs of Normandy
Formation & Location
Falaises des Vaches Noires, between Villers-sur-Mer and Houlgate, Normandy, France
Size & Dimensions
Approximately 20 to 25 mm in length, comparable to a standard 2 euro coin (25.75 mm diameter)
Value & Rarity
Estimated Market Value
5 to 15 USD
Auction Estimate
10 to 25 USD
Rarity Assessment
Common, frequently found weathered out of the rich fossiliferous clays and marls of the Vaches Noires formation
Scientific Significance
Provides evidence of shallow marine benthic environments in the ancient Anglo-Paris Basin during the Mesozoic era
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove loose clay matrix; store in a dry environment
Notable Features
Distinctively curved umbo and pronounced surface ribs typical of cement-attached oysters adapted to soft substrates
Notes
falaises des Vaches Noires