Rare Graphoceras (Lioceras) concavum Fossil Ammonite Inferior Oolite Jurassic Coast Burton Bradstock Dorset UK Genuine Specimen with COA

Exquisite Graphoceras (Lioceras) concavum Ammonite from the Inferior Oolite, Jurassic Coast, Dorset, UK

This beautiful Graphoceras (Lioceras) concavum fossil ammonite was discovered by our own team members, Alister and Alison, on 2 October 2025, at Burton Bradstock, Dorset, United Kingdom. The specimen was professionally cleaned, prepared, and treated by Alison, revealing its intricate ribbing and natural sheen. It originates from the Inferior Oolite Formation of the Jurassic Coast UNESCO World Heritage Site, dating to the Middle Jurassic (Aalenian–Lower Bajocian Stages, approximately 174–169 million years ago). This is a striking and scientifically significant ammonite representing one of the most distinctive faunal zones of the early Middle Jurassic seas.

Geological and Depositional Context

The Inferior Oolite Formation is a classic British Jurassic limestone sequence deposited under shallow marine conditions during the Middle Jurassic. It consists of alternating beds of fine-grained oolitic limestones, bioclastic sands, and calcareous muds formed in a warm, clear, subtropical sea that once covered much of southern England. The depositional environment was a calm, well-oxygenated marine platform teeming with ammonites, belemnites, and early marine reptiles.
The Burton Bradstock section lies along one of the most fossiliferous stretches of the Jurassic Coast, yielding ammonites that provide precise dating for the Inferior Oolite strata. Graphoceras (Lioceras) concavum occurs within the Concavum Zone, a globally recognised biozone used as a key stratigraphic marker for the early Bajocian. This makes specimens such as this one especially valuable to both collectors and scientists studying ammonite evolution and Jurassic stratigraphy.

Species Overview – Graphoceras (Lioceras) concavum

Graphoceras (Lioceras) concavum belongs to the family Graphoceratidae, superfamily Hildoceratoidea, order Ammonitida. This elegant species is characterised by its compressed, discoidal shell with fine, regular ribbing and a slightly concave whorl cross-section — the feature that inspired its species name, concavum. The ribs are typically simple, evenly spaced, and gently curved, giving the shell a graceful symmetry.
The smooth transitions between ribs and the narrow umbilicus contribute to its streamlined form, suggesting a fast-swimming, nektonic lifestyle within the mid-water column. These morphological adaptations reflect the dynamic and highly competitive marine ecosystems of the early Middle Jurassic, where ammonites diversified rapidly following earlier faunal turnovers.

Scientific Importance and Historical Context

The Graphoceras (Lioceras) concavum ammonite is of particular paleontological importance as an index fossil for the Concavum Biozone, widely used across Europe for correlating Jurassic rock sequences. Its evolutionary relationships link it closely to other genera such as Leioceras and Hyperlioceras, forming a key transitional group within the Hildoceratoidea lineage. The genus was first described in the 19th century by pioneering British geologists studying the Dorset and Somerset coastlines, helping to establish the foundations of modern ammonite stratigraphy.
Specimens from Burton Bradstock are especially prized for their preservation, with shells often retaining delicate ribbing and suture detail, providing valuable morphological data. The locality’s Inferior Oolite beds also hold historical significance, having been studied for over 150 years as part of the geological framework of the Jurassic Coast.

Condition, Provenance, and Authenticity

This 100% genuine fossil has been professionally collected and prepared to the highest standards. The specimen displays exquisite natural detail with fine ribbing, sharp sutures, and a compact whorl form characteristic of the species. The fossil has been carefully stabilised and treated by Alison to ensure durability while preserving its authentic geological character. The photograph shows the exact specimen you will receive, ensuring full transparency and authenticity.
A Certificate of Authenticity accompanies this specimen, confirming its species, provenance, geological age, and preparation history.

Details at a Glance

• Species: Graphoceras (Lioceras) concavum

• Family: Graphoceratidae

• Superfamily: Hildoceratoidea

• Order: Ammonitida

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

• Biozone: Concavum Zone

• Formation: Inferior Oolite

• Locality: Burton Bradstock, Dorset, United Kingdom

• Discovered by: Alister and Alison on 02 October 2025

• Prepared by: Alison

• Condition: Genuine, expertly prepared fossil with excellent preservation

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

• Included: Certificate of Authenticity

A True Collector’s Fossil from the Jurassic Coast

This Graphoceras (Lioceras) concavum ammonite is both scientifically valuable and visually captivating, showcasing the intricate natural beauty of Jurassic life from Britain’s world-famous fossil coastline. Collected and prepared by our own team, it stands as a timeless piece of geological history — a perfect addition to any serious fossil collection or natural history display.