Oyster fossil fragment
cf. Gryphaea / Exogyra sp. • Body fossil, invertebrate marine mollusk
Geological Period
Jurassic to Cretaceous (Late Jurassic / Callovian-Oxfordian or Cretaceous based on the Vaches Noires cliffs context)
Estimated Age
165 to 155 million years old
Preservation Type
Original calcitic shell material preserved with minor surface wear and encrusting matrix
Condition Assessment
Fair to Good; fragmentary and weathered, but preserves diagnostic ribbing and shell thickness
Taxonomic Classification
Phylum Mollusca, Class Bivalvia, Order Ostreida, Family Gryphaeidae or Ostreidae, Genus cf. Gryphaea or Exogyra
Morphological Description
Irregular, thick-shelled bivalve fragment displaying prominent radial ribs, growth lines, and an attachment area typical of cementing or reclining oysters.
Rock Matrix
Marly limestone and argillaceous matrix typical of coastal cliff exposures
Formation & Location
Falaises des Vaches Noires, Normandy, France
Size & Dimensions
Approximately 1.5 cm to 2 cm in maximum dimension, compared to full-sized specimens of 4 to 8 cm for typical taxa from this site
Value & Rarity
Estimated Market Value
$5 - $15
Auction Estimate
$10 - $30
Rarity Assessment
Common
Scientific Significance
Demonstrates shallow marine benthic paleoenvironments of the Jurassic/Cretaceous seaways in Western Europe
Preparation Recommendations
Gentle mechanical cleaning with a soft brush to remove loose clay matrix; store in a dry environment
Notable Features
Distinctive radial plications (folds) and rough outer shell texture indicative of high-energy shallow water or substrate attachment
Notes
falaises des Vaches Noires