Promicroceras and Cymbites Calcite Ammonite Fossil Jurassic Coast Black Ven Dorset UK Lyme Regis

Description

Specimen Overview

This exceptional fossil features a natural association of Promicroceras and Cymbites calcite ammonites, preserved together within the original matrix of the Black Ven Marls at Charmouth, near Lyme Regis, Dorset. The specimen has been carefully chosen for its clarity, balance, and visual appeal, showing two distinct ammonite genera on a single piece of Jurassic sediment. Pale calcite preservation highlights the shell forms beautifully against the darker marl background. The photographs show the exact fossil you will receive, with full sizing details clearly visible. As with all of our fossils, this specimen is 100% genuine and supplied with a Certificate of Authenticity.

Geological Formation & Provenance

The fossil originates from Black Ven, one of the most important fossil localities on the Jurassic Coast, a UNESCO World Heritage Site. The sediments here belong to the Lower Lias Group, deposited during the Early Jurassic Period, approximately 199–190 million years ago. The Black Ven Marls were laid down in a calm marine environment, offshore from the Jurassic coastline, where fine muds accumulated on the sea floor. These low-energy conditions allowed delicate shells to be buried rapidly, leading to the excellent preservation seen in ammonites from this area.

Fossil Type & Taxonomy

Both Promicroceras and Cymbites are extinct marine cephalopods belonging to the Class Cephalopoda, Subclass Ammonoidea, within the Order Ammonitida. These ammonites lived as free-swimming predators in Jurassic seas and are closely related to modern squid and cuttlefish. Promicroceras is typically associated with early Lower Lias ammonite assemblages, while Cymbites is known for its broader whorls and distinctive shell form. The presence of both genera together provides an excellent snapshot of Early Jurassic ammonite diversity.

Morphology & Preservation

The ammonites in this specimen display clear coiling and well-defined whorl outlines, allowing the natural shell geometry to be appreciated. Calcite replacement has preserved the original shell form while enhancing surface detail and providing a subtle crystalline texture. Growth lines and curvature can be observed, offering insight into the development of the animals during life. The surrounding marl matrix remains intact, preserving the ammonites in their original geological context rather than as isolated, removed shells.

Scientific & Collecting Significance

Lower Lias ammonites from Charmouth and Lyme Regis have been studied for over two centuries and were instrumental in the development of early geological and stratigraphic science. Both Promicroceras and Cymbites are important genera within Early Jurassic ammonite successions and are widely used in biostratigraphic studies. Fossils from Black Ven are internationally recognised for their reliable provenance and scientific credibility. A mixed-genus association such as this is particularly appealing, combining educational value with strong visual interest.

Display, Care & Authenticity

This fossil is ideal for display in a private collection, educational setting, or natural history cabinet. The specimen has been carefully cleaned to reveal natural features, with no artificial restoration or reconstruction applied. It remains exactly as preserved by nature. You will receive the exact fossil shown, accompanied by a Certificate of Authenticity, confirming its geological origin and genuine status.

A classic and scientifically meaningful piece from one of Britain’s most famous fossil cliffs, this Promicroceras and Cymbites calcite ammonite fossil represents a tangible fragment of Early Jurassic marine life from the Jurassic Coast.