Arnioceras Calcite Ammonite Fossil Jurassic Coast Black Ven Charmouth Dorset UK

Description

Specimen Overview

Offered here is a genuine Arnioceras calcite ammonite fossil from the classic Black Ven Marls at Charmouth, near Lyme Regis, Dorset. The specimen has been carefully chosen for its clear shell definition, natural presentation, and pleasing balance within the original marl matrix. Pale calcite replacement accentuates the ammonite’s spiral form against the darker sediment, allowing the shell’s morphology to be easily appreciated. The photographs show the exact fossil you will receive, with full sizing details visible in the images. As with all of our fossils, this piece is 100% genuine and supplied with a Certificate of Authenticity.

Geological Formation & Provenance

This fossil originates from Black Ven, one of the most productive and scientifically important fossil localities along the Jurassic Coast, a UNESCO World Heritage Site of global significance. The fossil-bearing strata belong to the Lower Lias Group, deposited during the Early Jurassic, approximately 199–196 million years ago. The Black Ven Marls comprise fine-grained marine mudstones laid down in a relatively calm offshore environment. These low-energy seabed conditions allowed ammonite shells to settle gently and become rapidly buried, protecting them from erosion and enabling the excellent preservation characteristic of this locality.

Fossil Type & Taxonomic Context

Arnioceras is an extinct genus of ammonite within the Class Cephalopoda, Subclass Ammonoidea, and Order Ammonitida. Ammonites were free-swimming marine molluscs closely related to modern squid and cuttlefish and were among the most successful predators in Jurassic seas. Arnioceras is a well-known Lower Lias ammonite and is frequently associated with early Jurassic ammonite assemblages, making it important for understanding both ammonite evolution and Early Jurassic stratigraphy.

Morphology & Preservation

This Arnioceras specimen displays the characteristic shell morphology of the genus, with clearly defined coiling and well-preserved whorl outlines. Subtle ribbing and growth features can be observed, reflecting the animal’s development during life. Calcite replacement has preserved the original shell geometry while enhancing surface detail, giving the fossil a gentle crystalline sheen when viewed under light. The surrounding marl matrix remains intact, preserving the ammonite in its original geological context rather than as a detached shell, which adds to its scientific and display value.

Scientific & Collecting Significance

Ammonites from Charmouth and Lyme Regis have been collected and studied for more than two centuries and were central to the early development of geological and stratigraphic science. Arnioceras is particularly valued within Early Jurassic ammonite successions and is commonly referenced in both academic literature and educational collections. Fossils from Black Ven are internationally recognised for their reliable provenance and stratigraphic integrity, making them highly desirable to collectors, educators, and those seeking an authentic British Jurassic ammonite.

Display, Care & Authenticity

This fossil is ideal for display in a private collection, educational setting, or natural history cabinet. The specimen has been carefully cleaned to reveal natural features, with no artificial restoration or reconstruction applied. It remains exactly as preserved by nature. You will receive the exact specimen shown, accompanied by a Certificate of Authenticity, confirming its geological origin and genuine status.

A classic and scientifically meaningful fossil from one of Britain’s most iconic fossil cliffs, this Arnioceras calcite ammonite represents an authentic and visually appealing piece of Early Jurassic marine history from the Jurassic Coast.