Promicroceras and Arnioceras Multi Block Fossil Ammonites Black Ven Marls Lower Lias Jurassic Coast Black Ven Lyme Regis Dorset UK

Description

Authentic Promicroceras and Arnioceras Multi Block Fossil Ammonites

This listing is for a genuine multi block of Promicroceras and Arnioceras ammonite fossils from the Black Ven Marls, Lower Lias, found at Black Ven on the Jurassic Coast, Lyme Regis, Dorset, UK. These ammonites are preserved together in a natural stone matrix, providing a visually striking and scientifically significant specimen that represents Early Jurassic marine life. The fossil pictured is the exact specimen you will receive, with a 1 cm scale cube included for accurate size reference.

The specimen was collected on 14 September 2025 by our team members Alister and Alison and has been carefully cleaned, prepped, and treated by Alison. It comes with a Certificate of Authenticity, ensuring it is a 100% genuine specimen with clear provenance.

Geological Context and Age

This fossil originates from the Black Ven Marls, part of the Lower Lias deposits exposed along the Dorset section of the UNESCO World Heritage-listed Jurassic Coast. These sediments were laid down in shallow seas during the Lower Jurassic, around 200 million years ago, preserving a wealth of marine life.

The Black Ven Marls are world famous for producing exceptionally well-preserved ammonites, which are used as index fossils in stratigraphy. The presence of both Promicroceras and Arnioceras together in one block provides a valuable window into the diversity of ammonite assemblages in the Early Jurassic.

Species Information – Promicroceras

Promicroceras is a small but highly distinctive ammonite genus within the order Ammonitida, superfamily Eoderoceratoidea, and family Eoderoceratidae. Its tightly coiled, evolute shell is adorned with fine ribbing and sometimes small tubercles, giving it a spiny appearance in well-preserved examples.

These ammonites were nektonic predators, actively swimming in the shallow seas of the Early Jurassic. Their rapid evolutionary changes make them important for defining ammonite biozones, and they are classic fossils of the Lower Lias deposits at Lyme Regis.

Species Information – Arnioceras

Arnioceras, another ammonite genus from the Lower Jurassic, belongs to the family Arietitidae, within the superfamily Eoderoceratoidea. These ammonites are characterised by their relatively evolute shells, with earlier coils visible, and strong ribbing that runs across the whorls. Their ornamented appearance makes them stand out among Lower Jurassic ammonites.

Like Promicroceras, Arnioceras was a nektonic predator, feeding on small invertebrates. Its distinct morphology and limited stratigraphic range make it another key index fossil, widely used in biostratigraphy.

Fossil Features and Preservation

This multi block specimen preserves several ammonites of both Promicroceras and Arnioceras within a single piece of matrix. The contrasting shell sizes, ribbing styles, and whorl shapes make this an especially appealing and scientifically informative specimen.

The ammonites are preserved in marlstone, with preparation work carefully exposing their details without compromising natural integrity. The preservation captures diagnostic features such as ribbing and coiling, making the ammonites clearly identifiable. The block format provides context for how ammonites were deposited together in Jurassic seas.

Collector and Scientific Significance

This specimen represents more than just a fossil—it is a snapshot of Early Jurassic ammonite diversity. Having Promicroceras and Arnioceras preserved together in one block demonstrates the range of ammonite forms living in the same marine ecosystem.

For collectors, this multi block offers strong provenance from the Black Ven Marls, one of the most iconic fossil localities in the world. Its combination of multiple genera, scientific importance, and display appeal makes it an excellent addition to any collection, whether private, educational, or museum-based.

A Rare Fossil from the Jurassic Coast

This Promicroceras and Arnioceras ammonite multi block is an authentic and striking specimen from the Lower Jurassic of Dorset. With careful preparation, strong provenance, and its supplied Certificate of Authenticity, it represents both a beautiful display piece and a scientifically valuable fossil from Britain’s Jurassic heritage.

All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.