Fossilized Burrow (Thalassinoides or Ophiomorpha)
Thalassinoides isp. • Trace fossil (ichnofossil), invertebrate burrow structure
Geological Period
Jurassic to Cretaceous (specifically Late Jurassic / Oxfordian or Cretaceous based on the Vaches Noires cliffs context)
Estimated Age
165 to 145 million years
Preservation Type
Permineralization and natural cast (filled with sediment that lithified differently from the surrounding matrix)
Condition Assessment
Good condition, largely complete cylindrical section with minor surface weathering and loss of fine exterior details
Taxonomic Classification
Ichnogenus Thalassinoides or Ophiomorpha, produced likely by decapod crustaceans (crabs or ghost shrimp)
Morphological Description
Elongated, sub-cylindrical burrow cast with a roughly textured, sandy-muddy surface, showing slight swellings and constrictions along its length without distinct pellet linings.
Rock Matrix
Calcareous marl and glauconitic chalk typical of coastal cliff deposits
Formation & Location
Falaises des Vaches Noires, Normandy, France (Callovian to Oxfordian formations)
Size & Dimensions
Approximately 8 to 10 cm in length and 2 cm in diameter, comparable to typical decapod burrow casts of this region
Value & Rarity
Estimated Market Value
$10 - $25
Auction Estimate
$15 - $30
Rarity Assessment
Common
Scientific Significance
Provides evidence of ancient benthic invertebrate behavior, bioturbation intensity, and paleo-oxygenation levels in shallow marine shelf environments
Preparation Recommendations
Gentle mechanical cleaning with a soft brush to remove loose matrix; store in a stable, dry environment requiring no special conservation treatments
Notable Features
Demonstrates clear three-dimensional cylindrical filling typical of crustacean burrow systems found eroding from coastal clay and marl cliffs
Notes
falaises des Vaches Noires