Rhynchonellid Brachiopod
Rhynchonella sp. cf. R. lorioli • Body fossil, invertebrate marine brachiopod
Geological Period
Jurassic (Callovian to Oxfordian epochs)
Estimated Age
163 to 157 million years ago
Preservation Type
Original calcitic shell material preserved with minor surface weathering and slight pyritization or limonitic staining
Condition Assessment
Good condition; mostly complete shell with minor wear on the margins and umbonal region, retaining clear structural ornamentation
Taxonomic Classification
Phylum Brachiopoda, Class Rhynchonellata, Order Rhynchonellida, Family Rhynchonellidae
Morphological Description
Small, sub-triangular to sub-pentagonal shell exhibiting prominent, sharp radial costae (ribs) radiating from the umbo toward the anterior margin. Deeply incised sulcus on the ventral valve and a corresponding fold on the dorsal valve producing a strongly zig-zagged anterior commissure.
Rock Matrix
Marly limestone and calcareous clay typical of the coastal deposits of Normandy
Formation & Location
Callovian and Oxfordian formations of the Vaches Noires cliffs (falasses des Vaches Noires), Normandy, France
Size & Dimensions
Approximately 12 mm in width, which is average to slightly small for typical Jurassic rhynchonellids from this locality
Value & Rarity
Estimated Market Value
$5 to $15 USD
Auction Estimate
$10 to $25 USD
Rarity Assessment
Common
Scientific Significance
Provides evidence of shallow shelf marine benthic paleoenvironments during the Middle to Late Jurassic transition in the Anglo-Paris Basin
Preparation Recommendations
Gentle mechanical cleaning using a soft brush and water or mild ultrasonic cleaning if matrix is clay-heavy; store in dry, stable humidity conditions
Notable Features
Well-defined costae and sharply defined plication at the anterior commissure demonstrating excellent hydrodynamic adaptation for filter feeding
Notes
falaises des Vaches Noires