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

Description

Genuine Promicroceras Ammonite from the Jurassic Coast

This listing features an authentic Promicroceras calcite ammonite fossil collected from the renowned Black Ven Marls, Black Ven, Lyme Regis, Dorset, along England’s iconic Jurassic Coast. The fossil shown in the photographs is the exact specimen you will receive, carefully selected for its preservation quality and scientific interest. Full sizing details are clearly shown in the images for accurate reference.

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

Geological Formation and Geological Age

This ammonite 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 of fine-grained marine mudstones and marls formed in a shallow epicontinental sea that once covered much of southern Britain. This formation is internationally important due to its exceptional abundance of ammonites and its long-standing role in establishing Jurassic stratigraphy. The continuous exposure at Black Ven has made Lyme Regis one of the most studied and celebrated fossil localities in the world.

Fossil Type, Species, and Scientific Classification

Promicroceras is a well-known Early Jurassic ammonite genus belonging to the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. This genus is widely used as an index fossil, allowing geologists to accurately identify and correlate Lower Lias marine sediments. Promicroceras is characteristic of the Promicroceras biozone, a key biostratigraphic interval within the Sinemurian, making specimens from this genus especially significant for both scientific study and serious fossil collections.

Morphology and Diagnostic Characteristics

This specimen displays the classic evolute shell coiling typical of Promicroceras, with earlier whorls clearly visible and a relatively wide umbilicus. The shell surface is decorated with strong, well-defined ribbing, often gently curved and occasionally bifurcating across the flanks, producing a bold and distinctive appearance. The ammonite has undergone natural calcite mineralisation, which enhances durability while preserving fine morphological detail. This calcite preservation highlights the original shell structure and adds visual contrast, making the fossil particularly attractive for display without compromising its natural integrity.

Depositional Environment

During the Early Jurassic, the Lyme Regis region 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 reduced scavenging and bioturbation, contributing to the excellent preservation seen in ammonites from the Black Ven Marls. These depositional conditions are key to the exceptional fossil record preserved along the Jurassic Coast.

Collecting, Display, and Educational Value

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