EXCEPTIONALLY RARE 11″ Calycoceras Fossil Chalk Ammonite | Lower Cenomanian Cretaceous | Chard Somerset UK | Alice Purnell Collection

Description

This listing features an EXCEPTIONALLY RARE 11-inch Calycoceras fossil ammonite preserved in chalk from the Lower Cenomanian Stage of the Cretaceous Period. Unearthed from Snowdon Hill, Chard, Somerset, United Kingdom, this stunning piece originates from the acclaimed Alice Purnell Collection—noted for its scientifically valuable and meticulously curated fossil specimens.

Geological Details:

• Locality: Snowdon Hill, Chard, Somerset, UK
• Geological Period: Cretaceous
• Geological Stage: Lower Cenomanian (~100.5 to 98 million years ago)
• Depositional Environment: Chalk sea; open, shallow marine setting dominated by calcareous plankton sedimentation, ideal for ammonite preservation
• Formation: Lower Chalk equivalent strata in southern England

Paleontological Context: Calycoceras is a genus of heteromorph ammonites in the Family Acanthoceratidae, known for their highly ornamented and often robust shells. These ammonites serve as valuable biostratigraphic indicators, especially within the Cenomanian sequence.

• Order: Ammonitida
• Superfamily: Acanthoceratoidea
• Family: Acanthoceratidae
• Genus: Calycoceras
• Species: Likely within Calycoceras naviculare group (based on regional horizon and morphology)
• Biozone: Lower Cenomanian, associated with the Mantelliceras mantelli Zone
• Formally Described by: Hypothetically referring to Calycoceras d’Orbigny, 1840s (depending on exact species)

Morphological Features:

• Exceptionally large shell (~11 inches across)
• Strong radial ribs crossing the whorls
• Pronounced tubercles along rib intersections
• Involute shell with deep umbilicus and broad outer whorl
• Preserved in chalk with light coloration and subtle calcite replacement

Notable Characteristics:

• Museum-grade size and preservation
• Rare UK locality specimen from Snowdon Hill, seldom available on the market
• Originates from the prestigious Alice Purnell Collection
• Excellent educational, research, or display value

Authenticity & Presentation:

• 100% genuine fossil, not a replica
• Includes Certificate of Authenticity
• Photo shows exact specimen you will receive
• Scale cube = 1cm for accurate size reference in photo

Additional Notes: Large and complete specimens of Calycoceras from British chalk deposits are exceedingly rare. This specimen not only stands out for its impressive size and completeness but also its exceptional provenance. A true centerpiece fossil suitable for the serious collector, educator, or museum collection.

All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.