Xipheroceras Calcite Ammonite Fossil Lyme Regis Jurassic UK Lower Lias Black Ven Marls Natural Crystal Ammonite Authentic Specimen

Description

Xipheroceras Calcite Ammonite – Jurassic Coast, Lyme Regis, Dorset

This beautiful Xipheroceras ammonite fossil is a genuine specimen from the famous Black Ven Marls of Charmouth, Lyme Regis, part of the UNESCO World Heritage Jurassic Coast in Dorset, UK. Dating to the Lower Lias of the Early Jurassic period, approximately 199–190 million years ago, this specimen showcases both exceptional fossil preservation and natural calcite crystal development.

Carefully selected for its aesthetic appeal and scientific value, this ammonite features natural calcite mineralisation within its chambers, giving it a striking crystalline appearance. The exact fossil shown in the photographs is the one you will receive, and it includes a Certificate of Authenticity lifetime guarantee generic card.

Geological Context – Black Ven Marls, Lower Lias Formation

The Black Ven Marls form part of the Lower Jurassic Lias Group, a sequence of clay-rich sediments deposited in a shallow marine environment that once covered much of southern England. These sediments are world-renowned for producing exceptionally preserved marine fossils, particularly ammonites and marine reptiles.

This specimen originates from deposits commonly associated with the Sinemurian stage of the Early Jurassic. The fine-grained marls allowed delicate shells to be rapidly buried, while periodic low-oxygen conditions on the seabed limited decay and disturbance. Over time, mineral-rich fluids permeated the sediment, leading to the formation of calcite crystals within the empty chambers of the ammonite shell.

Fossil Identification – Xipheroceras (Order: Ammonitida)

Xipheroceras is a well-known genus of early Jurassic ammonite belonging to the order Ammonitida, a group of extinct marine cephalopods related to modern squid and octopus. These organisms were highly successful and widely distributed throughout ancient oceans.

This genus is typically placed within the family Eoderoceratidae and the superfamily Eoderoceratoidea. It is characteristic of the early Jurassic ammonite assemblages and is often used in biostratigraphic studies due to its distinct morphology and relatively short stratigraphic range.

Morphology and Notable Features

This specimen displays classic features associated with Xipheroceras, combined with attractive mineralisation:

• Elegant coiled shell with defined whorls
• Fine ribbing across the shell surface, characteristic of the genus
• Visible chamber structure filled with natural calcite crystals
• Subtle contrast between fossil shell and surrounding matrix
• Natural preservation with no artificial enhancement

The calcite infill occurs where original shell chambers once contained gas or fluid, later replaced by crystalline mineral growth during diagenesis. This creates a visually striking effect, making each specimen unique.

Depositional Environment and Fossil Formation

During the Early Jurassic, the Lyme Regis region lay beneath a warm, shallow sea teeming with marine life. Ammonites such as Xipheroceras were active swimmers, occupying a key ecological role as both predators and prey.

After death, the shell would sink to the seabed and become buried in fine sediment. In low-energy conditions, the shell remained intact long enough for mineral-rich waters to infill the internal chambers. Over millions of years, calcite crystals formed within these voids, preserving both the structure and enhancing the visual appeal of the fossil.

Scientific and Collecting Significance

Ammonites like Xipheroceras are important index fossils, used by geologists to identify and correlate rock layers across different regions. Specimens from the Jurassic Coast are particularly valuable due to their well-documented geological context and historical importance.

Lyme Regis is one of the most famous fossil localities in the world, known for its contributions to early palaeontology. Fossils from this region continue to be highly sought after by collectors and institutions alike.

Calcite-filled ammonites are especially desirable, combining scientific interest with natural beauty, making them ideal for both display and study.

Authenticity and Presentation

This fossil is a 100% genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. The fossil shown in the photographs is the exact piece you will receive.

Full sizing is available within the listing images, allowing you to clearly assess the specimen before purchase.

Ideal for Collectors, Display, or Educational Use

This Xipheroceras calcite ammonite offers an excellent combination of geological significance, natural crystal formation, and visual appeal. Whether for a personal collection, educational display, or a unique gift, this fossil represents a genuine piece of Jurassic marine history from one of the most iconic fossil locations in the world.