Oxynoticeras Golden Pyrite Ammonite Fossil Lower Lias Jurassic Coast Charmouth Lyme Regis

Description

Oxynoticeras Golden Pyrite Ammonite Fossil from the Jurassic Coast

This exceptional Oxynoticeras Golden Pyrite Ammonite Fossil was collected at Stonebarrow Cliff, Charmouth, near Lyme Regis, Dorset, UK, one of the most renowned fossil sites along the UNESCO-designated Jurassic Coast. Discovered by our field collectors Alister and Alison on 06 November 2025, the fossil has been skilfully cleaned, prepared, and treated by Alison, bringing out its natural golden beauty while ensuring long-term stability. The photographs show the exact specimen you will receive, alongside a 1cm scale cube for accurate sizing. Your ammonite will arrive with a Certificate of Authenticity, confirming it as a 100% genuine fossil.

Species Overview: Oxynoticeras – A Classic Early Jurassic Ammonite

Oxynoticeras is a distinctive genus of ammonite belonging to the order Ammonitida, superfamily Eoderoceratoidea, and family Oxynoticeratidae. It thrived during the Lower Jurassic (Sinemurian Stage) and is well represented in the fossil-rich deposits of Charmouth and Black Ven.

Oxynoticeras ammonites are known for:

• Extremely compressed, discoidal shells
• Sharp, knife-like venter (outer rim)
• Fine, delicate ribbing that often becomes faint on later whorls
• Elegant, streamlined morphology reflecting strong hydrodynamic adaptation

These sleek ammonites are among the most visually refined fossils from the Lower Lias, and pyritised examples such as this one are particularly prized.

Golden Pyrite Preservation

The remarkable metallic gold appearance of this fossil results from natural pyritisation, a process in which the original aragonite shell is replaced by iron pyrite (FeS₂). This transformation occurs when ammonite shells are buried rapidly within:

• Low-oxygen marine muds
• Sulphur-rich sediment layers
• Stable, fine-grained deposits typical of the Black Ven Marls

Over millions of years, chemical reactions gradually convert the shell into pyrite, preserving even the most delicate ribbing and suture patterns. The result is a fossil that is not only scientifically significant but also visually spectacular.

Geological Context: Black Ven Marls, Lower Lias

The fossil originates from the Black Ven Marls, an iconic part of the Lower Lias Group, dating to the Early Jurassic (approximately 195–190 million years ago). These marls and mudstones were deposited in a calm, offshore marine environment with limited oxygen levels, ideal for preserving marine shells and soft-bodied organisms.

Stonebarrow Cliff, a continuous extension of these Lower Lias exposures, is famous for its prolific fossil layers. It produces some of the finest ammonites globally, including pyritised Oxynoticeras specimens.

The depositional environment featured:

• Fine-grained sedimentation of muds and silts
• Anoxic seabed conditions, slowing decay and preventing scavenger activity
• Rich biological activity, including ammonites, belemnites, fish, and marine reptiles

These conditions created a perfect environment for fossil preservation.

Morphological Features of This Specimen

This Oxynoticeras Golden Pyrite Ammonite exhibits several classic diagnostic features:

• Highly compressed shell profile, giving it a sleek, blade-like appearance
• Sharp, clean venter, characteristic of the genus
• Delicate ribbing, beautifully highlighted by the pyrite mineralisation
• Clear whorl progression, allowing easy identification
• Brilliant gold sheen, enhancing surface detail

The specimen’s preservation showcases the flowing, hydrodynamic elegance of Oxynoticeras, reflecting adaptations that allowed it to move efficiently through Early Jurassic seas.

Palaeoenvironment and Scientific Significance

During the Lower Jurassic, the Dorset coastline lay below a warm, shallow sea rich in life. Ammonites like Oxynoticeras played an important ecological role as agile swimmers, feeding on small marine animals and forming part of a diverse marine community shared with belemnites, fish, crustaceans, and ichthyosaurs.

Pyritised ammonites from Stonebarrow are highly valued by researchers and collectors alike because they demonstrate both shell morphology and fossilisation processes with exceptional clarity.

Display and Collector Appeal

This Oxynoticeras Golden Pyrite Ammonite is an outstanding specimen suitable for collectors, educational displays, interior décor, or anyone fascinated by natural geological artistry. The dramatic golden sheen, combined with the slender shell morphology, makes it an eye-catching display piece from every angle.

Prepared with care by Alison and sourced from one of the world’s most important fossil sites, this ammonite carries both scientific value and aesthetic beauty.

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