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

Description

Authentic Promicroceras Ammonite from the Jurassic Coast

Presented here is a genuine Promicroceras calcite ammonite fossil recovered from the renowned Black Ven Marls at Black Ven, Lyme Regis, Dorset, on England’s world-famous Jurassic Coast. The specimen shown in the photographs is the exact fossil you will receive, carefully chosen for its preservation quality, scientific relevance, and visual appeal. Full sizing details are shown in the photos for clear and accurate reference.

All of our fossils are 100% genuine specimens and are supplied with a Certificate of Authenticity, providing complete confidence in provenance and legitimacy.

Geological Formation and Age

This ammonite originates from the Lower Lias Group, dating to the Early Jurassic Period, approximately 199–191 million years ago, within the Sinemurian Stage. The Black Ven Marls consist primarily of fine-grained marine mudstones and marls deposited in a shallow epicontinental sea that once covered much of southern Britain. This formation is internationally significant due to its exceptional fossil abundance and its importance in defining Jurassic stratigraphy. The continuous exposures at Black Ven make this locality one of the most important reference sections for Early Jurassic marine life.

Fossil Type, Species, and Scientific Classification

Promicroceras is a classic Early Jurassic ammonite genus belonging to the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. This genus is widely recognised as an index fossil, meaning it is particularly valuable for dating and correlating Lower Lias marine sediments. Promicroceras is characteristic of the Promicroceras biozone, a key biostratigraphic interval within the Sinemurian Stage, making specimens from this genus highly sought after by collectors and students of palaeontology.

Morphology and Notable Characteristics

This specimen displays the distinctive evolute shell coiling typical of Promicroceras, with earlier whorls clearly visible and a relatively wide umbilicus. The shell is ornamented with strong, well-defined ribbing, often gently curved and occasionally bifurcating across the flanks, creating a bold and recognisable appearance. The ammonite has undergone natural calcite mineralisation, which enhances durability while preserving fine morphological detail. This mineralisation highlights the original shell structure and adds visual contrast without detracting from the fossil’s natural authenticity.

Depositional Environment

During the Early Jurassic, the Lyme Regis area lay beneath a warm, shallow marine environment with generally calm water conditions. Fine sediments settled slowly on the sea floor, allowing ammonite shells to be rapidly buried after death. Periodic low-oxygen conditions limited scavenging and bioturbation, contributing to the excellent preservation of ammonites within the Black Ven Marls. These environmental conditions are a key reason why the Jurassic Coast is internationally renowned for the quality and abundance of its fossils.

Collecting, Display, and Educational Value

This Promicroceras calcite ammonite fossil is ideal for private fossil collections, educational use, museum displays, or refined interior presentation. Its classic British provenance, well-defined stratigraphic position, and attractive preservation make it both scientifically meaningful and visually engaging. Each specimen we offer is individually selected, ensuring you receive a carefully curated and authentic piece of Early Jurassic marine history from one of the most important fossil localities in the world.