Rhynchonelliform Brachiopod or Gryphaea Fragment
Rhynchonella cf. boueti or similar Jurassic brachiopod • Body fossil, invertebrate marine fossil
Geological Period
Jurassic (Callovian to Oxfordian)
Estimated Age
165 to 155 million years
Preservation Type
Calcitic replacement and pyritization within a fine-grained matrix
Condition Assessment
Fair, partial specimen with visible surface wear and matrix adhesion, moderately complete but showing weathering typical of tidal collection
Taxonomic Classification
Phylum Brachiopoda, Class Rhynchonellata, Order Rhynchonellida, Family Rhynchonellidae
Morphological Description
Displays distinct radial ribbing (costae) converging toward the umbo, characteristic of rhynchonellid brachiopods, showing a roughly triangular to sub-pentagonal outline with a prominent fold and sulcus visible on the anterior margin.
Rock Matrix
Clay-rich marl and glauconitic limestone typical of coastal cliff deposits
Formation & Location
Vaches Noires cliffs (Falaises des Vaches Noires), Normandy, France
Size & Dimensions
Approximately 20 mm in maximum length, comparable to standard medium-sized Jurassic brachiopods from the region
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 benthic communities in the Mesozoic European epicontinental seas during the Jurassic period
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove adhering clay matrix; store in a dry, stable environment to prevent potential pyrite decay
Notable Features
Distinctive radiating costae and robust shell fragment structure typical of high-energy shallow marine Jurassic deposits
Notes
falaises des Vaches Noires