Promicroceras Calcite Fossil Ammonites in Woodstone Jurassic Coast Charmouth Lyme Regis Dorset UK

Description

Promicroceras Calcite Ammonites in Woodstone

This listing is for a rare and striking specimen of Promicroceras Calcite Fossil Ammonites preserved in Woodstone (Petrified Calcite Wood) from the Black Ven Marls, Lower Lias, Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK. The fossil dates back to the Early Jurassic (Sinemurian stage, around 200 million years ago). This extraordinary piece combines the beauty of multiple calcite ammonites preserved within a block of petrified calcite-rich fossilised wood, creating a highly collectable and unusual natural association. It was discovered by our own team members, Alister and Alison, on 11th September 2025, and has been expertly cleaned, prepped, and treated by Alison to reveal both the ammonite details and the petrified wood structure.

Geological Provenance – Black Ven Marls and Jurassic Coast

The Black Ven Marls are part of the Lower Lias sequence along the Dorset coast, an area of global geological importance designated as a UNESCO World Heritage Site. These deposits were laid down in a shallow marine environment, preserving countless ammonites, belemnites, bivalves, marine reptiles, and occasional plant material washed into the sea. Fossils preserved in Woodstone are particularly special, as they represent a rare occurrence where driftwood became buried in Jurassic sediments and subsequently mineralised, often encapsulating ammonites and other marine life. The combination of calcite ammonites within fossilised wood is an exceptional find, adding both geological rarity and natural artistry.

Species Profile – Promicroceras

The genus Promicroceras belongs to the Order Ammonitida, Superfamily Psiloceratoidea, and the Family Promicroceratidae. These small ammonites are among the most recognisable and scientifically important species of the Lower Jurassic. Promicroceras ammonites are characterised by their tightly coiled shells, narrow rounded whorls, and fine ribbing, which creates an elegant and intricate spiral pattern. Despite their modest size, they are crucial index fossils for the Lower Sinemurian stage, used by paleontologists to date and correlate Early Jurassic rock formations across Europe.

Morphology and Preservation in Woodstone

This specimen showcases multiple Promicroceras ammonites, each with the characteristic ribbed coiling and compact spiral form of the genus. The ammonites are preserved in calcite, which has replaced the original aragonite shell material over millions of years, producing a crystalline effect that enhances structural clarity. The surrounding petrified calcite wood adds an extraordinary context, preserving the ancient marine interaction between driftwood and ammonite life. Such specimens are not only scientifically intriguing but also aesthetically unique, making them highly desirable for collectors.

Scientific and Stratigraphic Significance

Promicroceras ammonites mark the Promicroceras planicosta biozone, a critical subdivision of the Sinemurian stage. Their wide distribution and evolutionary importance make them one of the most valuable ammonite groups for biostratigraphy. The preservation of these ammonites within fossilised woodstone provides further paleoenvironmental insight, reflecting both the biodiversity of the Early Jurassic seas and the occasional terrestrial input into the marine ecosystem. Such multi-component specimens are rare and offer a unique perspective on the complexity of ancient environments.

Authenticity and Presentation

All of our fossils are 100% genuine specimens and each comes with a Certificate of Authenticity. The photographs show the exact specimen you will receive, not a stock image. For accurate sizing, a 1 cm scale cube is included in the photographs. This ammonite and woodstone association has been carefully prepared to highlight the natural details of both the ammonites and the fossilised wood, making it a perfect specimen for collectors, educational use, or natural history display.

This Promicroceras Calcite Fossil Ammonites in Woodstone from the Black Ven Marls of Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK, is a highly unusual and scientifically significant specimen that beautifully combines ammonite fossils with petrified calcite wood, offering a rare glimpse into the Early Jurassic world.