Oyster Shell Fossil
Exogyra cf. virgula or Gryphaea species • Body fossil, invertebrate bivalve
Geological Period
Jurassic to Cretaceous (Callovian to Cenomanian based on the Vaches Noires locality)
Estimated Age
165 to 90 million years
Preservation Type
Original calcitic shell material largely preserved with some degree of permineralization and surface wear due to marine erosion.
Condition Assessment
Fair to Good; the specimen is an isolated, worn shell fragment showing surface weathering and loss of fine marginal details, but retaining its overall three-dimensional shape.
Taxonomic Classification
Phylum: Mollusca, Class: Bivalvia, Order: Ostreida, Family: Ostreidae, Genus: Gryphaea or Exogyra
Morphological Description
Elongated, somewhat comma-shaped or irregular asymmetrical bivalve shell with a thick, robust construction, showing a prominent curved umbo and rough, undulating growth lines across the exterior surface.
Rock Matrix
Glauconitic limestone and calcareous sandstone typical of the Vaches Noires coastal cliffs.
Formation & Location
Falaises des Vaches Noires, Normandy, France; Oxfordian/Kimmeridgian formations
Size & Dimensions
Approximately 4 to 5 cm in length, consistent with medium-sized fossil oysters from this region and comparable in scale to the adjacent 2-euro coin (25.75 mm diameter).
Value & Rarity
Estimated Market Value
5 to 15 USD
Auction Estimate
Not typically sold at auction individually; common educational or hobbyist specimen value
Rarity Assessment
Common
Scientific Significance
Provides evidence of shallow marine Jurassic/Cretaceous ecosystems along the ancient European shelf seas, useful for paleoecological and regional stratigraphic studies.
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove residual matrix clay; store in a dry, stable environment.
Notable Features
Slightly coiled umbo characteristic of cemented oysters (Ostreidae), showing clear signs of natural tumbling and wave wear from beach collecting at the Vaches Noires site.
Notes
falaises des Vaches Noires