Rare Stephanoceras Ammonite Fossil, Inferior Oolite Formation, Jurassic Period, Burton Bradstock Dorset England

Description

Authentic Stephanoceras Ammonite Fossil – Inferior Oolite Formation, Jurassic Dorset

This stunning Stephanoceras ammonite fossil is an exceptional and genuine specimen from the Inferior Oolite Formation, discovered by our own team members Alister and Alison on 14 October 2023 at Burton Bradstock, Dorset, UK. The fossil has been professionally cleaned, prepared, and treated by Alison, revealing the exquisite ribbing and spiral form characteristic of this iconic Jurassic genus.

A remarkable example of British palaeontology, this piece captures the beauty and complexity of life that thrived in the warm shallow seas of the Middle Jurassic, approximately 170 million years ago. The specimen is a unique collector’s piece, fully authentic and mounted with precision to highlight its natural aesthetic and historical value.

Geological Context – Inferior Oolite Formation

The Inferior Oolite Formation is a series of sedimentary limestone and marl deposits dating from the Bajocian Stage of the Middle Jurassic. The formation is widely exposed along the Dorset coast and represents an ancient shallow marine environment, where warm seas supported a rich ecosystem of ammonites, brachiopods, echinoids, and marine reptiles.

Formed in a low-energy, carbonate-rich depositional setting, the Inferior Oolite owes its name to the oolitic limestone texture — composed of small spherical grains (ooids) formed by calcium carbonate precipitation in agitated marine water. These conditions were ideal for the preservation of marine fossils, particularly ammonites like Stephanoceras, whose robust shells were quickly buried and mineralised within fine sediment.

This particular specimen originates from the Burton Bradstock locality, part of the Jurassic Coast World Heritage Site, renowned for its consistent exposure of Middle Jurassic strata and its importance in understanding ammonite biostratigraphy and palaeoecology.

Stephanoceras – Iconic Middle Jurassic Ammonite

Stephanoceras is a genus of large, strongly ribbed ammonites belonging to the family Stephanoceratidae, within the order Ammonitida and the superfamily Stephanocerataceae. It is one of the most recognisable and scientifically significant ammonites of the Bajocian Stage, often used as an index fossil for dating Middle Jurassic deposits across Europe.

These ammonites are characterised by their broad whorls, coarse radial ribs, and tuberculate ornamentation along the flanks. The shell’s ribbing pattern, typically bifurcating near the ventrolateral shoulder, gives Stephanoceras a striking appearance and made it one of the most robust ammonites of its time. The spiral symmetry and intricate suture lines reveal an evolutionary lineage adapted to open marine environments, where it likely thrived as a free-swimming carnivore, preying on smaller molluscs and crustaceans.

The fossil’s excellent preservation showcases these diagnostic features in fine detail — the ribbed surface, visible growth lines, and partial septal suture traces reflect both the biological artistry and geological endurance of this ancient cephalopod.

Palaeontological Significance and Discovery

Discovered and collected by our field team, Alister and Alison, this specimen is a genuine product of careful fossil hunting along the Dorset coast. The Burton Bradstock cliffs are part of the famous Inferior Oolite sequence, a formation that has yielded numerous type specimens of Bajocian ammonites. Fossils from this region continue to contribute to modern palaeontological studies in ammonite taxonomy, evolution, and stratigraphic correlation.

Each Stephanoceras ammonite specimen is not only a collector’s treasure but also a vital scientific record — a time capsule from the Jurassic sea that helps reconstruct the life, climate, and ocean chemistry of an ancient world long vanished beneath the waves.

Display, Provenance, and Authenticity

The scale cube (1 cm) shown in the accompanying photograph provides an accurate size reference, and the image displays the exact specimen you will receive. The fossil has been professionally prepared to a museum-grade standard, ensuring both stability and aesthetic presentation.

All of our specimens are 100% genuine fossils, never replicas or casts, and each comes with a Certificate of Authenticity confirming its identity, locality, and geological context.

This Stephanoceras ammonite fossil from the Inferior Oolite Formation of Burton Bradstock is a magnificent representation of Jurassic marine life — a beautiful, scientifically significant piece that brings the wonder of deep geological time into your collection.