Oyster or Gryphaea fossil
cf. Gryphaea arcuata or related Jurassic oyster species • Body fossil, invertebrate bivalve mollusc
Geological Period
Jurassic (Callovian to Oxfordian epochs)
Estimated Age
163 to 157 million years old
Preservation Type
Original calcitic shell material preserved via permineralization and minor recrystallization
Condition Assessment
Good condition; somewhat weathered and encrusted with matrix, partial completeness of the outer shell margins
Taxonomic Classification
Phylum: Mollusca, Class: Bivalvia, Order: Ostreida, Family: Gryphaeidae, Genus: Gryphaea or Exogyra
Morphological Description
Exhibits a strongly curved, thickened lower valve with pronounced concentric growth lines and radiating ridges or costae typical of attached or resting epifaunal bivalves. The overall shape is irregular, elongate-oval with a prominent umbo.
Rock Matrix
Argillaceous limestone / marly clay matrix typical of coastal cliff formations
Formation & Location
Falaises des Vaches Noires, Normandy, France
Size & Dimensions
Approximately 25 mm in length, which is slightly smaller than the adjacent 2-euro coin (25.75 mm diameter)
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $25 USD
Rarity Assessment
Common, frequently found in the Jurassic strata of the Vaches Noires cliffs
Scientific Significance
Provides evidence of shallow marine shelf paleoenvironments along the northern margin of the Paris Basin during the Late Jurassic
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove adhering clay matrix; store in a dry environment
Notable Features
Collected from the famous fossil-rich Vaches Noires cliffs, displaying classic oyster-like ribbed ornamentation and curved umbonal region
Notes
falaises des Vaches Noires