Xipheroceras Fossil Ammonite Black Ven Marls Lower Lias Jurassic Coast Lyme Regis Dorset UK

Authentic Xipheroceras Fossil Ammonite from the Jurassic Coast

This impressive Xipheroceras Fossil Ammonite is an authentic and beautifully preserved specimen from the Black Ven Marls, Lower Lias Formation, discovered on the Jurassic Coast at Black Ven, Lyme Regis, Dorset, UK. Dating to the Lower Jurassic period (approximately 195–200 million years ago), this ammonite is a striking example of early Jurassic marine life and an important index fossil for the Sinemurian Stage.

Your specimen was discovered by our team members, Alister and Alison, on 09 October 2025, and has been expertly cleaned, prepped, and treated by Alison to reveal its fine ribbing and distinctive shell detail. The photograph shows the exact specimen you will receive, ensuring full authenticity and provenance.

Geological Context and Origin

This specimen comes from the Black Ven Marls Member of the Charmouth Mudstone Formation, part of the Lower Lias Group along the UNESCO World Heritage-listed Jurassic Coast. The Black Ven cliffs, situated between Charmouth and Lyme Regis, are renowned worldwide for their exceptional preservation of marine fossils — a heritage first made famous by Mary Anning’s pioneering discoveries in the early 19th century.

The Black Ven Marls were deposited in a low-energy, offshore marine environment consisting of fine muds and silts. These sediments were laid down under oxygen-poor (anoxic) conditions, which greatly reduced decay and allowed marine organisms to be preserved in remarkable detail. Occasional sediment slumps or storm surges led to rapid burial, forming fossil beds rich in ammonites, belemnites, and marine reptile remains.

The layer that yields Xipheroceras corresponds to the Sinemurian Stage of the Lower Jurassic, particularly within the Xipheroceras dudressieri Zone, which bears the name of this genus. This zone serves as a key biostratigraphic marker across Europe.

Scientific Classification

• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Subclass: Ammonoidea
• Order: Ammonitida
• Superfamily: Eoderoceratoidea
• Family: Eoderoceratidae
• Genus: Xipheroceras
• Age: Early Jurassic (Sinemurian Stage)
• Formation: Black Ven Marls, Lower Lias
• Locality: Black Ven, Lyme Regis, Dorset, UK

Xipheroceras is one of the most characteristic ammonites of the Sinemurian and is widely used as an index fossil for correlating lower Jurassic marine deposits across Europe. Its distinct morphology makes it a favourite among collectors and palaeontologists alike.

Morphological Features and Preservation

This Xipheroceras ammonite displays the genus’s iconic features — an evolute shell (with all whorls visible), broad, spaced ribs, and a strongly ornamented venter with occasional tubercles or nodules near the outer flanks. The ribs curve forward slightly and often bifurcate, giving the shell a sense of motion even in stone. These bold ribs are diagnostic of Xipheroceras dudressieri, one of the best-known species from this horizon.

The fossil shows excellent preservation, with the surface detail and ribbing crisply defined. Some areas exhibit subtle calcite mineralisation, adding a natural sheen that highlights the intricate shell texture. The scale cube (1 cm) in the photograph provides size reference, and full measurements are included in the listing images. This is a well-balanced, display-quality specimen showcasing the natural form and symmetry of a true Jurassic ammonite.

Palaeobiological and Scientific Significance

Ammonites such as Xipheroceras were fast-moving marine cephalopods, related to modern squids and cuttlefish. Their chambered shells allowed for buoyancy control through a system of gas- and fluid-filled compartments, enabling them to move efficiently through the ancient seas of what is now southern England.

Xipheroceras represents an evolutionary stage following Echioceras and preceding the more advanced ammonites of the Pliensbachian Stage. Its robust, highly ribbed shell indicates an adaptation to dynamic marine conditions, possibly reflecting ecological niches near coastal or mid-depth environments.

These ammonites are important in palaeontological research, helping scientists understand early Jurassic biodiversity, stratigraphic zonation, and environmental change during a critical period of marine evolution.

Authenticity and Provenance

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity. Each piece is responsibly collected, professionally prepared, and carefully stabilised to preserve its natural integrity. No replicas or artificial enhancements are used — the fossil shown is the actual piece you will receive.

This Xipheroceras Fossil Ammonite is an exceptional example of British Jurassic heritage — a scientifically important and visually striking specimen from the legendary Black Ven cliffs of Lyme Regis, Dorset, capturing the timeless beauty and evolutionary story of life from 200 million years ago.