Cymbites Calcite Ammonite Fossil Split Birchi Nodule Black Ven Marls Lower Lias Jurassic Coast Charmouth Lyme Regis Dorset UK

Description

Genuine Cymbites Calcite Ammonite Fossil from the Jurassic Coast

This listing is for a beautifully preserved Cymbites calcite ammonite fossil from a split Birchi nodule, found in the Black Ven Marls, Lower Lias, Jurassic Coast: Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK. Dating back to the Early Jurassic Period (approximately 197–200 million years ago), this ammonite is an authentic and scientifically important specimen from one of the most famous fossil-bearing localities in the world.

Discovered by our own team members Alister and Alison on 12 September 2025, this ammonite has been meticulously cleaned, prepped, and treated by Alison to ensure that the natural calcite detail is revealed without compromising the integrity of the fossil. The photographs provided show the exact specimen you will receive, with a 1 cm scale cube for reference. Every fossil also comes with a Certificate of Authenticity for peace of mind.

Geological and Stratigraphic Significance

This fossil originates from the Black Ven Marls, a part of the Lower Lias Group, exposed along the Jurassic Coast World Heritage Site. The Birchi nodules within these beds are renowned for their ability to preserve ammonites in exceptional detail, often filled with striking calcite.

The Lower Lias was deposited in a shallow marine environment, where fine sediments buried marine organisms quickly, preserving them in remarkable condition. This particular ammonite belongs to the Sinemurian Stage, a key division of the Early Jurassic, which is widely used by palaeontologists for biostratigraphic correlation.

About Cymbites Ammonites

Cymbites is a genus of extinct ammonites within the family Cymbitidae, superfamily Eoderoceratoidea, order Ammonitida. These ammonites are characterised by their relatively small to medium size, rounded whorls, and ribbed ornamentation. Their shells often reveal intricate suture lines, which are diagnostic features used in species identification.

The calcite preservation within this specimen is particularly attractive, as the mineral has replaced the original aragonite shell material, giving the fossil a natural polish and luster. Collectors prize Cymbites fossils for their combination of aesthetic beauty and scientific importance, especially when preserved in split nodules that reveal both internal and external details.

Morphological Features

This specimen clearly shows the ribbed coiling of the ammonite, with its chambers filled in calcite. When nodules are split, one half often reveals the internal cast of the ammonite, while the other preserves external shell detail, allowing a rare dual perspective of the fossil’s morphology. These split nodules are especially prized by both collectors and educational institutions because they demonstrate how fossils form and are preserved within rock.

Scientific and Collector Value

Ammonites like Cymbites are important as index fossils, allowing scientists to date the rock layers in which they are found with high precision. They help define the biozones of the Sinemurian Stage, making them critical to geological and palaeontological studies.

For collectors, this specimen represents not only an ancient marine creature but also a fragment of the Jurassic Coast’s fossil heritage, a region made famous by fossil pioneer Mary Anning. The combination of calcite preservation, split nodule form, and geological provenance makes this an exceptional addition to any collection.

A Unique Piece of Natural History

Owning this Cymbites calcite ammonite fossil from a split Birchi nodule means holding a direct link to the Jurassic seas of nearly 200 million years ago. Its natural beauty, geological context, and scientific importance make it a prized specimen for collectors, educators, and fossil enthusiasts alike.

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