Promicroceras Calcite Ammonite Fossil Jurassic Lyme Regis Dorset UK Lower Lias Black Ven Marls

Description

Authentic Jurassic Ammonite from Lyme Regis

Presented here is a genuine Promicroceras calcite ammonite fossil from the renowned Black Ven Marls, Black Ven, Lyme Regis, Dorset, part of England’s world-famous Jurassic Coast. The photographs show the exact specimen you will receive, carefully chosen for quality, clarity, and scientific interest. Full sizing details are provided within the images.

All of our fossils are 100% genuine specimens and each comes complete with a Certificate of Authenticity, ensuring confidence for collectors, educators, and enthusiasts.

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 consist primarily of fine marine mudstones and marls formed in a shallow epicontinental sea. This formation is internationally significant due to its fossil abundance and stratigraphic continuity, making it one of the most important Early Jurassic fossil sites in Europe. Fossils from this locality are highly prized for both their scientific reliability and historic importance.

Fossil Type and Classification

Promicroceras is a classic Early Jurassic ammonite genus belonging to the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. This genus is widely used as an index fossil, meaning it is particularly valuable for dating and correlating Lower Jurassic marine sediments. Promicroceras is closely associated with the Promicroceras biozone, a key biostratigraphic marker within the Lower Lias of southern England, making specimens from this genus especially desirable to collectors with an interest in stratigraphy and palaeontology.

Morphology and Preservation

This specimen displays the characteristic evolute coiling typical of Promicroceras, with earlier whorls clearly visible around a relatively wide umbilicus. The shell surface shows distinct, well-defined ribbing, often gently curved and occasionally bifurcating across the flanks, creating a visually striking and diagnostic appearance. The fossil has undergone calcite mineralisation, a natural process that enhances structural strength while preserving fine surface detail. This calcite infill highlights the original shell form and adds to the specimen’s aesthetic appeal without detracting from its natural authenticity.

Depositional Environment

During the Early Jurassic, the Lyme Regis area lay beneath a warm, shallow marine environment with relatively calm conditions. Fine sediments settled slowly on the sea floor, allowing ammonite shells to be buried rapidly after death. Periodic low-oxygen conditions reduced scavenging and disturbance, contributing to the excellent preservation seen in ammonites from the Black Ven Marls. These environmental factors are key to the exceptional fossil record of the Jurassic Coast.

Ideal for Collection and Display

This Promicroceras calcite ammonite is an excellent addition to private fossil collections, educational settings, museums, or refined home displays. Its classic British provenance, clear stratigraphic placement, and attractive preservation make it both scientifically meaningful and visually appealing. Each specimen we offer is individually selected, ensuring you receive a genuine and carefully curated piece of Early Jurassic marine history from one of the world’s most celebrated fossil localities.