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

Description

Authentic Promicroceras Ammonite from the Jurassic Coast

This listing features a genuine Promicroceras calcite ammonite fossil from the historic Black Ven Marls, located at Black Ven, Lyme Regis, Dorset, on England’s internationally recognised Jurassic Coast. The specimen shown in the photographs is the exact fossil you will receive, carefully chosen for its quality, preservation, and scientific relevance. Full sizing details are clearly shown in the images provided.

All of our fossils are 100% genuine specimens and are supplied with a Certificate of Authenticity, ensuring 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, within the Sinemurian Stage. The Black Ven Marls consist of fine-grained marine mudstones and marls formed in a shallow epicontinental sea that covered much of southern Britain at the time. This geological formation is world-famous for its dense concentration of ammonites and its importance in defining Jurassic stratigraphy. Fossils from Black Ven are especially valued due to the continuous and well-documented sedimentary sequence preserved at this locality.

Fossil Type, Species, and Scientific Classification

Promicroceras is a classic Early Jurassic ammonite genus within the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. This genus plays a key role in biostratigraphy and is widely recognised as an index fossil. Promicroceras is characteristic of the Promicroceras biozone, making it an important marker for correlating Lower Lias marine deposits across Europe. Specimens from Lyme Regis are particularly well-studied and form part of the foundation of British Jurassic palaeontology.

Morphology and Preservation Details

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, giving the ammonite a bold and recognisable appearance. The fossil has undergone natural calcite mineralisation, which enhances both durability and visual contrast while preserving fine morphological detail. This style of preservation highlights the original shell structure and adds significant aesthetic appeal.

Depositional Environment

During the Early Jurassic, the Lyme Regis area lay beneath a warm, shallow marine environment with calm water conditions. Fine sediments settled slowly on the seabed, allowing ammonite shells to be rapidly buried after death. Periodic low-oxygen conditions reduced scavenging and bioturbation, resulting in the excellent preservation for which the Black Ven Marls are renowned. These conditions contributed to the exceptional abundance and quality of ammonites recovered from this site.

Collecting, Display, and Educational Value

This Promicroceras calcite ammonite is an excellent choice for private collectors, educational use, museum displays, or refined interior presentation. Its classic British provenance, clear stratigraphic placement, and attractive preservation make it both scientifically meaningful and visually striking. 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 most important fossil localities in the world.