Xipheroceras Fossil Ammonite Black Ven Marls Lyme Regis Jurassic Coast Dorset UK Genuine Specimen with Certificate

Xipheroceras Fossil Ammonite – Black Ven Marls, Lower Lias, Lyme Regis

This genuine Xipheroceras fossil ammonite originates from the famous Black Ven Marls of the Lower Lias on the Jurassic Coast at Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK. The specimen was discovered by our own team members, Alister and Alison, on 28 February 2025 and has been professionally cleaned, prepped and treated by Alison to ensure excellent presentation and long-term stability.

This fossil includes a Certificate of Authenticity lifetime guarantee generic card. The photographs show the exact specimen you will receive, and full sizing details are clearly provided in the listing images.

Fossil Identification and Classification

Xipheroceras is an Early Jurassic ammonite belonging to:

• Order: Ammonitida

• Suborder: Ammonitina

• Superfamily: Eoderoceratoidea

• Family: Eoderoceratidae

The genus Xipheroceras is characteristic of the Lower Lias and is particularly associated with the Sinemurian Stage of the Early Jurassic, approximately 199 to 190 million years ago. Specimens from the Black Ven Marls are often linked to specific ammonite biozones within the Sinemurian, which are important for detailed stratigraphic correlation along the Dorset coast.

Ammonites such as Xipheroceras are index fossils, meaning they evolved rapidly and had widespread geographic distribution, making them essential tools for dating sedimentary rock layers.

Geological Setting – Black Ven Marls, Lower Lias

The Black Ven Marls are part of the Lower Lias Group, deposited during the Early Jurassic in a shallow epicontinental sea that covered much of what is now southern England. These sediments consist mainly of dark grey to black clays and marls, representing low-energy marine depositional environments.

Periodic sediment influx, fluctuating oxygen levels, and fine-grained marine mud allowed exceptional preservation of marine life, including ammonites, bivalves, marine reptiles, and other invertebrates.

Stonebarrow Cliff and the wider Lyme Regis area form part of the UNESCO World Heritage Jurassic Coast, internationally recognised for its geological significance and continuous record of Triassic, Jurassic and Cretaceous strata.

Morphology and Notable Features

Xipheroceras is known for its evolute shell form, meaning the whorls are not tightly enveloped, allowing earlier whorls to remain visible. The shell typically displays strong ribbing, often bifurcating (splitting) as the ribs cross the flanks and extend toward the outer whorl.

The ribbing pattern and whorl section are key identifying features within the Eoderoceratidae. The preserved detail in specimens from the Black Ven Marls can show fine growth lines and well-defined rib structure, reflecting both biological growth and sedimentary preservation conditions.

The coiled planispiral shell represents an extinct marine cephalopod that once inhabited Jurassic seas, using a chambered shell for buoyancy regulation.

Discovery and Preparation

This specimen was discovered in situ by Alister and Alison on 28 February 2025 along Stonebarrow Cliff. Following recovery, Alison carefully cleaned, stabilised and prepared the fossil to enhance visibility of morphological detail while preserving the integrity of the original matrix.

Preparation has been carried out sympathetically, retaining natural surface characteristics and geological context.

Authenticity and Collector Appeal

This Xipheroceras Fossil Ammonite is a genuine Jurassic Coast specimen and includes a Certificate of Authenticity lifetime guarantee generic card. The fossil shown in the photographs is the exact piece you will receive, carefully chosen for its quality, locality significance, and preservation.

A Lower Lias ammonite from the Black Ven Marls represents an important part of Early Jurassic marine history. With confirmed provenance, documented discovery date, and professional preparation, this specimen offers both scientific and collector value from one of the world’s most celebrated fossil localities.