Promicroceras Double Calcite Ammonite Fossil Cut Base Jurassic Lyme Regis Dorset UK

Description

Authentic Promicroceras Double Ammonite Block from the Jurassic Coast

Offered here is a genuine Promicroceras double block calcite ammonite fossil with a cut base, collected from the renowned Black Ven Marls at Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, part of England’s world-famous Jurassic Coast. This specimen preserves two Promicroceras ammonites naturally associated within a single block, creating a visually striking and scientifically meaningful fossil display. The photographs show the exact specimen you will receive, carefully selected for balance, preservation, and overall presentation. Full sizing details are shown in the photos.

This fossil is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card, ensuring confidence in provenance and long-term collectability.

Geological Formation and Age

This fossil originates from the Lower Lias Group, deposited during the Early Jurassic Period, approximately 199–191 million years ago, within the Sinemurian Stage. The Black Ven Marls are composed of fine-grained marine mudstones and marls formed in a shallow epicontinental sea that once covered southern Britain. Stonebarrow Cliff is one of the most important Lower Jurassic fossil localities in Europe, internationally recognised for its abundance of ammonites that underpin Jurassic stratigraphy and palaeoenvironmental interpretation.

Fossil Type, Species, and Scientific Context

The ammonites preserved within this block belong to the genus Promicroceras, part of the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. Promicroceras is a classic Lower Lias index fossil, closely associated with the Promicroceras biozone, making it particularly important for biostratigraphic correlation of Early Jurassic marine sediments. Double ammonite blocks of this genus are especially desirable, as they preserve multiple individuals in close association, reflecting original sea-floor accumulation.

Morphology and Calcite Preservation

Both ammonites display characteristic planispiral coiling with compact, evolute shells and strong, regular ribbing across the flanks. Ribbing is well defined and evenly spaced, allowing clear observation of growth stages. Calcite mineralisation enhances shell detail and gives the ammonites a pale, crystalline appearance that contrasts beautifully with the darker marl matrix.

The cut base has been professionally prepared to allow the specimen to stand upright securely, making it ideal for cabinet, shelf, or desk display without additional supports while retaining the fossil’s natural integrity.

Depositional Environment

During the Early Jurassic, the Charmouth and Lyme Regis region lay beneath a warm, shallow marine environment rich in ammonites, belemnites, fish, and marine reptiles. Periodic storm events and sediment influx led to the accumulation of ammonite shells on the sea floor. Rapid burial by fine sediments, combined with low-oxygen conditions, reduced scavenging and disturbance, allowing multiple ammonites to be preserved together within the Black Ven Marls. This specimen represents a genuine snapshot of an Early Jurassic sea-floor assemblage.

Collecting, Display, and Educational Value

This Promicroceras double block calcite ammonite fossil with cut base is ideal for serious fossil collectors, educational collections, museum displays, or refined interior presentation. Its combination of two diagnostically important ammonites, classic British Jurassic provenance, and practical display preparation makes it both scientifically informative and visually impressive. Double ammonite blocks from Stonebarrow Cliff are increasingly scarce and highly sought after. Each specimen we offer is individually selected to ensure you receive an authentic and carefully curated piece of Early Jurassic marine history from one of the world’s most important fossil coastlines.