Graphoceras concavum Fossil Ammonite Jurassic Middle Bajocian Dorset Coast UK Certified | Rare Lioceras from Burton Bradstock England

Description

Authentic Graphoceras (Lioceras) concavum Fossil Ammonite from Dorset

This listing presents a rare and well-preserved Graphoceras (Lioceras) concavum fossil ammonite, collected from the Middle Bajocian stage of the Jurassic, Burton Bradstock, Dorset Coast, United Kingdom. Ammonites of this type are highly significant both scientifically and for collectors, as they serve as vital biostratigraphic markers while also being visually striking specimens. The photographs show the exact fossil you will receive, with a 1 cm scale cube included for accurate measurement.

All of our fossils are 100% genuine specimens, supplied with a Certificate of Authenticity to guarantee provenance and quality.

Geological Setting – Jurassic Middle Bajocian, Concavum Zone

This ammonite originates from the Concavum Zone of the Middle Bajocian (approx. 170–168 million years ago). The Dorset Coast, part of the UNESCO World Heritage Jurassic Coast, is internationally recognised for its exceptional fossil record, spanning 185 million years of geological history. Burton Bradstock is a key locality within this sequence, famous for ammonites that provide invaluable evidence for understanding Jurassic marine ecosystems.

The Concavum Zone, defined by Graphoceras (Lioceras) concavum, plays a crucial role in Jurassic stratigraphy. This species is one of the most important index fossils of the Bajocian, making it indispensable for correlating rock layers across Europe.

Fossil Type and Scientific Classification

• Species: Graphoceras (Lioceras) concavum
• Genus: Graphoceras (subgenus Lioceras)
• Family: Graphoceratidae
• Superfamily: Hildoceratoidea
• Order: Ammonitida

This ammonite belongs to the Graphoceratidae family, a group characterised by their finely ribbed, compressed shells. The genus Graphoceras and its subgenus Lioceras are central to Bajocian ammonite zonation.

Morphological Features

This specimen displays the diagnostic features of Graphoceras (Lioceras) concavum:

• A compressed, planispiral shell with narrowly rounded whorls.
• Fine, dense ribbing across the flanks, giving the shell a distinctive textured appearance.
• A smooth venter (outer margin) with ribs that fade or weaken as they cross it.
• Clear suture patterns along the shell surface, typical of ammonites.
• An overall elegant, streamlined form reflecting adaptations for active swimming.

These features not only make the species instantly recognisable but also scientifically important as they define the Concavum Zone within the Bajocian stage.

Scientific and Collector Importance

Graphoceras (Lioceras) concavum is a classic ammonite of the Middle Jurassic, renowned for its role in defining the Concavum biozone. Its wide distribution and well-preserved shells make it one of the most important ammonites for stratigraphic correlation.

For collectors, this fossil represents an outstanding opportunity to own a rare ammonite from the famous Dorset Jurassic Coast. Its ribbed texture, elegant coiling, and historical significance make it a highly desirable addition to any fossil collection, whether for display, education, or research purposes.

Depositional Environment

During the Middle Jurassic, the Dorset region was submerged beneath warm, shallow seas rich in marine life. Fine sedimentation of clay and limestone created ideal conditions for fossil preservation, allowing ammonites such as Graphoceras concavum to be fossilised in detail. These seas supported diverse marine faunas, from ammonites and belemnites to large reptiles, making the fossil record of Dorset one of the most complete anywhere in the world.

Guarantee of Authenticity

Every fossil we sell is 100% genuine, carefully selected for preservation and quality. A Certificate of Authenticity accompanies each specimen, providing reassurance of provenance. The photographs show the exact ammonite fossil you will receive, with accurate scale provided.

This Graphoceras (Lioceras) concavum fossil ammonite from the Concavum Zone of the Middle Bajocian, Burton Bradstock, Dorset Coast is a scientifically important and visually appealing specimen – a rare piece of Britain’s Jurassic heritage.