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

Description

Genuine Jurassic Ammonite from the World-Famous Jurassic Coast

Offered here is an authentic Promicroceras calcite ammonite fossil collected from the celebrated Black Ven Marls, Black Ven, Lyme Regis, Dorset, along England’s internationally renowned Jurassic Coast. The specimen shown in the photographs is the exact fossil you will receive, carefully selected for quality, clarity, and scientific integrity. Full sizing details are clearly shown in the accompanying images.

All of our fossils are 100% genuine specimens and each is supplied with a Certificate of Authenticity, providing complete 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 are composed of fine-grained marine mudstones and marls that accumulated in a shallow epicontinental sea. This formation is globally significant for its abundance of well-preserved ammonites and its importance in establishing Jurassic stratigraphy. The continuous sedimentary sequence at Black Ven makes fossils from this locality especially reliable for geological correlation and study.

Fossil Type, Species, and Classification

Promicroceras is a classic Early Jurassic ammonite genus belonging to the Order Ammonitida, Superfamily Eoderoceratoidea, and Family Echioceratidae. This genus is particularly important as an index fossil, widely used to identify and date Lower Lias marine sediments. Promicroceras is characteristic of the Promicroceras biozone, a key biostratigraphic interval within the Sinemurian, making specimens from this genus highly sought after by both collectors and academic institutions.

Morphology and Diagnostic Features

This specimen displays the distinctive evolute coiling typical of Promicroceras, with earlier whorls clearly visible around a moderately wide umbilicus. The shell exhibits strong, well-defined ribbing, often gently curved and occasionally bifurcating across the flanks, creating a striking and easily recognisable form. The ammonite has undergone natural calcite mineralisation, which enhances durability while preserving fine surface detail. This mineralisation highlights the original shell structure and contributes to the fossil’s visual appeal without compromising 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 become rapidly buried after death. Periodic low-oxygen conditions limited scavenging and disturbance, contributing to the exceptional preservation seen in ammonites from the Black Ven Marls. These conditions explain why this locality has produced some of the most iconic and scientifically important ammonite fossils in the world.

Collecting, Display, and Educational Value

This Promicroceras calcite ammonite is an excellent choice for private fossil collections, educational use, museum displays, or refined interior presentation. Its classic British provenance, well-understood stratigraphic position, and attractive preservation make it both scientifically meaningful and visually engaging. Each specimen we offer is individually chosen, ensuring you receive a genuine and carefully curated piece of Early Jurassic marine history from one of the most important fossil sites on Earth.