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

Description

Genuine Jurassic Ammonite from the Iconic Jurassic Coast

This offering features a Promicroceras calcite ammonite fossil recovered from the famous Black Ven Marls at Black Ven, Lyme Regis, Dorset, along England’s world-renowned Jurassic Coast. The specimen shown in the photographs is the exact fossil you will receive, carefully selected for quality and scientific integrity. Full sizing details are provided in the images for complete transparency.

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

Geological Formation and Age

The fossil originates from the Lower Lias Group, deposited during the Early Jurassic Period, approximately 199–191 million years ago. The Black Ven Marls are composed predominantly of fine-grained marine mudstones and marls laid down in a shallow epicontinental sea. This area represents one of the most important Lower Jurassic fossil localities in Europe, providing a near-continuous stratigraphic record and exceptional ammonite preservation. The geological setting allows fossils from this locality to be reliably placed within the Sinemurian Stage, making them both scientifically valuable and highly collectable.

Fossil Type and Taxonomy

Promicroceras is a classic Early Jurassic ammonite genus belonging to the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. This genus is especially important in biostratigraphy and is widely recognised as an index fossil, used to correlate and date Lower Jurassic marine sediments. Promicroceras is closely associated with the Promicroceras biozone, a key marker horizon within the Lower Lias sequence of southern England.

Morphology and Preservation

This specimen displays the distinctive evolute coiling typical of Promicroceras, with earlier whorls clearly visible around a wide umbilicus. The shell exhibits well-defined ribbing, often gently curved or bifurcating across the flanks, creating a visually striking and diagnostic appearance. The fossil has undergone calcite mineralisation, which enhances surface detail and preserves the original shell form with excellent clarity. This style of preservation not only improves durability but also highlights the natural structure of the ammonite, making it ideal for display.

Depositional Environment

During the Early Jurassic, the Lyme Regis area lay beneath a warm, shallow sea with relatively calm conditions. Fine sediments settled slowly on the sea floor, allowing ammonite shells to be rapidly buried after death. Periodic low-oxygen conditions reduced disturbance by scavengers, contributing to the abundance and quality of ammonites preserved within the Black Ven Marls. These environmental factors are key to why this locality has produced some of the most famous ammonite specimens in the world.

Ideal for Collectors, Study, and Display

This Promicroceras calcite ammonite is well suited for serious fossil collectors, educational use, academic reference, or elegant display. Its clear stratigraphic origin, classic British provenance, and attractive preservation make it a timeless and meaningful addition to any collection. Each specimen we offer is individually chosen, ensuring you receive a genuine and scientifically significant piece of Early Jurassic marine history.