Eteoderoceras Golden Pyrite Fossil Ammonite Lower Lias Black Ven Marls Jurassic Coast Charmouth Dorset UK

Description

Authentic Eteoderoceras Golden Pyrite Fossil Ammonite

This exceptional Eteoderoceras Golden Pyrite Fossil Ammonite is a stunning, genuine specimen from the Black Ven Marls, Lower Lias Formation, discovered along the Jurassic Coast at Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK. Dating back to the Lower Jurassic period (approximately 195–200 million years ago), this ammonite is a spectacular example of pyritised fossilisation, where natural iron sulphide minerals have replaced the original shell, creating a gleaming golden appearance.

Your specimen was discovered by our own team members, Alister and Alison, on 23 October 2025, and has been professionally cleaned, prepped, and treated by Alison to reveal its exceptional details. The photographs show the actual specimen you will receive, ensuring complete transparency and authenticity.

Geological Context and Origin

This fossil originates from the Black Ven Marls Member of the Charmouth Mudstone Formation, part of the Lower Lias Group along the UNESCO World Heritage Jurassic Coast. The Stonebarrow and Black Ven cliffs are among the most famous fossil-rich localities in the world, known for yielding perfectly preserved ammonites, belemnites, and marine reptiles. These strata were deposited in a low-energy, offshore marine environment characterised by fine-grained muds and siltstones.

During the Early Jurassic, the seabed often experienced oxygen-poor (anoxic) conditions, which prevented decay and allowed for the remarkable preservation of marine fauna. As sediments compacted over millions of years, iron sulphides within the muds crystallised around the decaying shells, replacing the original aragonite material with pyrite (FeS₂). This process, known as pyritisation, created the golden metallic finish that makes ammonites from this region so distinctive and sought-after.

The fossil belongs to the Sinemurian–Pliensbachian boundary interval of the Early Jurassic, a crucial stage for ammonite diversification following the end-Triassic mass extinction.

Scientific Classification

• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Subclass: Ammonoidea
• Order: Ammonitida
• Superfamily: Eoderoceratoidea
• Family: Eoderoceratidae
• Genus: Eteoderoceras
• Age: Early Jurassic (Sinemurian–Pliensbachian)
• Formation: Black Ven Marls, Lower Lias
• Locality: Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK

Eteoderoceras is an important index fossil for the Lower Jurassic and serves as a reference genus for defining the Eteoderoceras ammonite biozone used in European stratigraphy. Specimens from this zone are prized for both their scientific and aesthetic qualities.

Morphological Features and Preservation

This Eteoderoceras specimen exhibits the genus’s characteristic evolute coiling, with each whorl fully visible from the side and defined by bold, gently curving ribs. The ribs are strong and regularly spaced, radiating symmetrically from the umbilicus to the venter (outer rim). Some ribs bifurcate toward the outer edge, producing a graceful and rhythmic pattern typical of Eteoderoceras.

The fossil’s entire surface has been pyritised, giving it a shimmering golden metallic finish that enhances the fine structural details. The scale cube (1 cm) in the image provides a reference for size, and full measurements are listed in the accompanying photographs. The specimen’s natural shape and coloration make it a display-quality piece, suitable for collectors, educators, and enthusiasts alike.

The fossil’s preparation has carefully exposed its ribbing and suture lines — the intricate junctions between shell chambers — while preserving the lustrous mineral coating. The combination of structural integrity and natural brilliance makes this ammonite a rare and beautiful example of fossil artistry created by nature itself.

Palaeobiological and Scientific Significance

Ammonites such as Eteoderoceras were free-swimming marine cephalopods, closely related to modern squids and cuttlefish. They used their chambered shells (phragmocones) for buoyancy control, allowing them to navigate the water column while preying on plankton and small crustaceans.

Eteoderoceras is notable for its evolutionary position within the early ammonite lineage, displaying transitional features that link earlier Sinemurian forms with the more elaborate ammonites of the Pliensbachian Stage. Its shell morphology reflects adaptations to open-marine habitats, where hydrodynamic efficiency and shell strength were vital for survival.

Fossils from the Black Ven Marls are crucial to our understanding of early Jurassic marine ecosystems, and pyritised specimens such as this one offer insights into both ancient life and the geochemical conditions that governed fossil preservation.

Authenticity and Provenance

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity. Each piece is responsibly collected, professionally prepared, and stabilised for long-term preservation. No replicas or artificial enhancements are ever used — what you see is the true fossil as discovered and naturally preserved over millions of years.

This Eteoderoceras Golden Pyrite Fossil Ammonite is a perfect representation of Britain’s Jurassic heritage, combining scientific importance, geological beauty, and natural artistry in one exquisite specimen from the world-famous Jurassic Coast at Charmouth, Dorset.