Very Rare Graphoceras gisoni Ammonite Fossil Jurassic UK with COA

Description

Very Rare Graphoceras gisoni Ammonite Fossil

This genuine ammonite fossil is identified as Graphoceras gisoni and comes from Stocking Farm at Illey in the West Midlands, United Kingdom. It is preserved from the Inferior Oolite Group and dates to the Aalenian Stage of the Middle Jurassic. The photographs show the actual carefully chosen fossil offered for sale, so the specimen pictured is the exact ammonite you will receive.

Aalenian Middle Jurassic Age

The Aalenian is the earliest stage of the Middle Jurassic Period, spanning approximately 174 to 170 million years ago. During this interval, parts of Britain were covered by warm shallow seas. These marine environments supported ammonites, bivalves, gastropods, brachiopods, echinoids, and other organisms. Sediments accumulated on the sea floor and later became the limestones, iron-rich beds, sands, and clays associated with the Inferior Oolite succession.

After death, an ammonite shell could settle onto the sea floor and become buried by sediment. Compaction, mineral replacement, and long-term geological alteration preserved the shell or its internal mould as a fossil. The documented Aalenian age gives this specimen a well-defined place near the beginning of the Middle Jurassic.

Graphoceras gisoni

Graphoceras was an extinct marine cephalopod with a planispirally coiled, chambered shell. The animal lived in the final body chamber, while earlier sealed chambers assisted with buoyancy control. Ammonites were relatives of modern squid, cuttlefish, and nautiluses, although they formed their own diverse and now extinct branch of cephalopod evolution.

Graphoceras is an important Aalenian ammonite genus. Typical representatives have compressed, evolute to moderately involute shells with distinct ribbing and a ventral keel. Rib style, whorl proportions, umbilical width, and outer-shell form are among the features used to distinguish related species and interpret growth. Examine the photographs for the coiled whorls, rib pattern, keel region, umbilical area, natural matrix, and preserved surface detail visible on this individual Graphoceras gisoni.

Scientific and Stratigraphic Interest

Ammonites evolved rapidly and were distributed widely through Jurassic seas. Their changing shell forms make them valuable index fossils, helping geologists correlate sedimentary rocks and establish relative ages. Graphoceras is particularly associated with Aalenian strata and contributes to understanding the ammonite succession of the early Middle Jurassic.

An ammonite shell grew by adding progressively larger chambers around the outer whorl. Internal septa met the shell wall along complex suture lines, strengthening the chambered structure. External ribs and the ventral keel also formed important elements of shell architecture and may have affected both strength and movement through the water.

Inferior Oolite Group Geology

The Inferior Oolite Group is a classic British Middle Jurassic rock succession. Its name refers to oolitic limestones formed from tiny rounded carbonate grains, although the group also includes varied marine sediments. These rocks record repeated changes in water depth, sediment supply, seabed conditions, and marine communities.

Stocking Farm at Illey provides a specific West Midlands provenance that adds valuable geographical and geological context. A fossil from a named locality can complement a collection arranged by British county, rock unit, geological stage, ammonite genus, or ancient marine environment.

Rare Collectable Specimen

Graphoceras gisoni is offered here as a very rare species-level fossil. Natural colour, mineral texture, small breaks, areas of wear, and variations in preservation reflect its long geological history. These are expected features of an authentic fossil rather than manufacturing defects. Every specimen preserves a different combination of shell material, mineral replacement, internal mould, and surrounding rock.

The multiple photographs show this exact ammonite from useful angles. They allow close inspection of its condition, ornament, outline, matrix, proportions, and display character. Full sizing is shown in the photographs, which provide the clearest scale information for this individual piece. The images are not stock photographs and do not represent a similar specimen.

Certificate of Authenticity

This genuine fossil includes a generic Certificate of Authenticity card with a lifetime guarantee. Its rare species identification, Aalenian age, Inferior Oolite provenance, and authentic natural preservation make it a distinctive addition to a fossil cabinet, specialist ammonite collection, study display, or educational setting. It is also a memorable gift for anyone interested in British Jurassic geology, rare ammonites, palaeontology, or genuine natural history specimens.