Rare 5″ Leioceras Fossil Ammonite Inferior Oolite Jurassic Coast Burton Bradstock Dorset UK Genuine Specimen with COA

Beautiful 5″ Leioceras Ammonite from the Inferior Oolite, Jurassic Coast, Dorset, UK

This stunning 5-inch Leioceras fossil ammonite was discovered by our own team members, Alister and Alison, on 2 October 2025, at Burton Bradstock, Dorset, United Kingdom, a renowned locality along the Jurassic Coast UNESCO World Heritage Site. The fossil was meticulously cleaned, prepped, and treated by Alison, revealing exquisite ribbing and definition. As a classic ammonite of the Inferior Oolite Formation, this specimen dates from the Middle Jurassic Period (Aalenian–Bajocian Stages, approximately 174–169 million years ago). It represents one of the most elegant and scientifically important ammonite types from the early part of the Jurassic Coast succession.

Geological and Depositional Context

The Inferior Oolite Formation forms part of the Middle Jurassic marine sequences of southern England and is world-famous for its beautifully preserved ammonites, brachiopods, and marine vertebrate remains. These rocks were deposited in a warm, shallow epicontinental sea, characterised by fine-grained limestones, ooids, and calcareous muds. The depositional environment was one of low energy and high biological productivity — ideal conditions for fossilisation.
The Burton Bradstock section exposes the upper Inferior Oolite beds, which were laid down on the Jurassic seafloor roughly 170 million years ago. These sediments, enriched with calcium carbonate, encased the shells of marine organisms, preserving them with exceptional detail. Fossils from this area have long been prized by collectors and researchers for their high quality and historical importance.

Species Overview – Leioceras

Leioceras is a genus within the family Graphoceratidae, superfamily Hildoceratoidea, order Ammonitida. These ammonites are known for their distinctive smooth to finely ribbed shells, strong involution, and moderately compressed whorls. The name Leioceras derives from the Greek “leios,” meaning smooth — a fitting description for its elegant, streamlined morphology.
The shell of Leioceras is typically discoidal, with a relatively narrow umbilicus and subtle growth lines that radiate gently across the flanks. This morphology suggests a free-swimming, nektonic lifestyle, with the animal using jet propulsion to move swiftly through the Middle Jurassic seas. The genus is a key biostratigraphic indicator for the Leioceras opalinum Zone, part of the Aalenian Stage, marking a well-defined horizon in the global Jurassic stratigraphic record.

Scientific and Historical Significance

Leioceras ammonites are among the most recognisable index fossils of the early Middle Jurassic. Their short stratigraphic range and wide geographic distribution make them essential for correlating marine sedimentary sequences across Europe. They also provide valuable insight into evolutionary transitions within ammonoid lineages following the faunal diversification of the Early Jurassic.
The presence of Leioceras in the Inferior Oolite reflects a stable, well-oxygenated marine environment, with nutrient-rich conditions that supported diverse cephalopod, bivalve, and brachiopod populations. Specimens from Dorset are particularly significant for their clarity of preservation, revealing both the biological beauty and geological history of the Jurassic Coast.

Condition, Provenance, and Authenticity

This is a 100% genuine fossil ammonite, professionally discovered, prepared, and authenticated. The surface displays intricate ribbing and delicate natural detail, with subtle mineralisation enhancing its texture and contrast. The fossil has been gently cleaned and treated by Alison to preserve its natural integrity.
The photograph shows the exact specimen you will receive, ensuring complete transparency and authenticity. A Certificate of Authenticity is provided, verifying the fossil’s species, geological age, formation, and provenance.

Details at a Glance

• Species: Leioceras sp.

• Family: Graphoceratidae

• Superfamily: Hildoceratoidea

• Order: Ammonitida

• Age: Aalenian–Bajocian Stages, Middle Jurassic (~174–169 million years ago)

• Formation: Inferior Oolite

• Locality: Burton Bradstock, Dorset, United Kingdom

• Discovered by: Alister and Alison on 02 October 2025

• Prepared by: Alison

• Condition: Genuine, fully prepared, display-quality fossil

• Scale: Cube = 1 cm (see photo for full sizing)

• Included: Certificate of Authenticity

A Premier Collector’s Fossil from the Jurassic Coast

This Leioceras fossil ammonite is a superb representation of Britain’s Jurassic heritage — scientifically valuable, visually striking, and steeped in geological history. Collected from one of the most celebrated fossil localities in the world, this specimen stands as a timeless connection to the ancient seas of the Middle Jurassic and a perfect addition to any collection of fine fossils.