Arnioceras Ammonite Fossil Jurassic Lyme Regis Dorset Lower Lias Black Ven

Description

Authentic Arnioceras Ammonite from the Jurassic Coast

Offered here is a genuine Arnioceras fossil ammonite, collected from the classic Black Ven Marls at Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK. This iconic stretch of coastline forms part of the UNESCO-listed Jurassic Coast, globally renowned for its exceptional Early Jurassic fossil record. The specimen has been carefully selected for its preservation and overall visual quality. The photographs show the exact fossil you will receive, and full sizing details are clearly shown in the photos for complete transparency.

This fossil is a 100% genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card, providing long-term confidence in provenance and authenticity.

Geological Formation and Age

This ammonite originates from the Lower Lias Group, deposited during the Early Jurassic Period, approximately 199–191 million years ago, within the Sinemurian Stage. The Black Ven Marls consist of fine-grained marine mudstones and marls laid down in a shallow epicontinental sea that covered much of southern Britain at the time. Stonebarrow Cliff is one of the most important Lower Jurassic localities in Europe, yielding abundant and stratigraphically significant ammonites that underpin Jurassic biostratigraphy.

Fossil Type, Species, and Scientific Context

Arnioceras is a well-known Early Jurassic ammonite genus belonging to the Order Ammonitida, Superfamily Psiloceratoidea, and Family Arietitidae. It is characteristic of the lower Sinemurian and is frequently used in ammonite zonation schemes for the Lower Lias. Arnioceras is widely illustrated in scientific literature and museum collections due to its distinctive morphology and importance in understanding early ammonite evolution following the end-Triassic extinction.

Morphology and Notable Features

This specimen displays classic planispiral coiling with relatively broad, rounded whorls and clearly defined ribbing across the shell surface. The ribs are typically strong and evenly spaced, giving Arnioceras its robust and recognisable appearance. Growth lines and whorl expansion are visible, allowing the ammonite’s ontogenetic development to be appreciated. Preservation quality enables clear observation of shell form and ornamentation, making this specimen both informative and visually appealing.

Depositional Environment

During the Early Jurassic, the Charmouth and Lyme Regis area lay beneath a warm, shallow marine sea rich in ammonites, belemnites, bivalves, echinoderms, and early marine reptiles. Fine sediments settled on the sea floor, periodically burying shells soon after death. These low-energy conditions promoted fossilisation and resulted in the exceptional preservation seen within the Black Ven Marls. This environment is key to why the Jurassic Coast remains one of the most important fossil sites in the world.

Collecting, Display, and Educational Value

This Arnioceras ammonite fossil is ideal for serious fossil collectors, educational collections, museum-style displays, or refined interior presentation. Its classic British Jurassic provenance, clear taxonomic identification, and strong visual presence make it suitable for both scientific interest and decorative display. Ammonites from Stonebarrow Cliff are increasingly sought after due to their stratigraphic importance and consistent quality. Each specimen we offer is individually chosen to ensure you receive an authentic and well-presented example of Early Jurassic marine life from one of the world’s most celebrated fossil coastlines.