Fossil Ammonite Kosmoceras jasoni Jurassic Callovian Wiltshire UK Genuine Specimen COA

Description

Genuine Jurassic Kosmoceras jasoni Ammonite from Wiltshire, UK

This listing presents a Kosmoceras jasoni ammonite fossil from the Callovian Stage of the Jurassic Period (approximately 166–163 million years ago). The specimen originates from Wiltshire, United Kingdom, a region renowned for yielding exceptional ammonite fossils that have been key in defining the Jurassic stratigraphy of Britain. The fossil shown in the photographs is the exact piece you will receive, with a 1 cm scale cube for reference. All of our fossils are guaranteed genuine and are accompanied by a Certificate of Authenticity.

Geological Context

The Callovian Stage marks an important interval of the Middle Jurassic, when much of southern England was submerged beneath shallow, warm epicontinental seas. These seas supported diverse marine life, including ammonites, belemnites, bivalves, and marine reptiles. Fossils from Wiltshire are often preserved within clay-rich marine sediments, reflecting a low-energy seabed environment where delicate shell features could survive burial and fossilisation.

Kosmoceras jasoni is one of the most significant ammonites from the Lower Callovian, forming part of the Jason Zone, a crucial biozone used by geologists and palaeontologists to date and correlate Jurassic rock layers across Europe. This makes specimens of this species not only visually striking but also scientifically valuable.

Scientific Classification

• Type: Fossil Ammonite
• Genus: Kosmoceras
• Species: jasoni
• Order: Ammonitida
• Superfamily: Stephanoceratoidea
• Family: Kosmoceratidae
• Age: Callovian Stage, Jurassic (~166–163 million years ago)
• Locality: Wiltshire, United Kingdom
• Biozone: Jason Zone (Lower Callovian)

Morphological Features

This specimen of Kosmoceras jasoni displays the distinct traits typical of the species and family:

• Coiling: Strongly evolute shell, where most whorls are clearly visible from the side.
• Ribbing: Bold, radiating ribs extend across the flanks, many of which bifurcate, giving the shell a striking ornamented appearance.
• Tubercles: Characteristic nodes or tubercles are often present along the ribs, especially at the ventrolateral shoulders.
• Venter: The outer edge of the shell typically shows a keeled or rounded profile, depending on preservation.
• Sutures: Complex suture patterns form beautiful natural designs, reflecting the intricate internal chamber structure.

These features make Kosmoceras jasoni one of the most recognisable and desirable ammonites from the Jurassic seas of Britain.

Paleoecology and Importance

Ammonites such as Kosmoceras jasoni were nektonic marine mollusks, related to modern squid and octopuses. They used their chambered shells for buoyancy control, allowing them to hunt smaller marine organisms throughout the Jurassic seas.

The Kosmoceratidae family played an important role in Jurassic marine ecosystems, and their abundance and rapid evolutionary changes make them excellent index fossils. The Jason Zone, named for this species, is critical for identifying and correlating Lower Callovian strata across Europe, highlighting its enduring importance in paleontology.

Collector’s Value

This Jurassic ammonite fossil represents not only a window into the life of the Middle Jurassic seas but also a key scientific marker in the geological record. The specimen’s strong ribbing, coiling, and surface detail give it both aesthetic and academic appeal.

Collectors of British ammonites will value this piece for its provenance from Wiltshire, a county with a long history of significant fossil discoveries. As ammonites from the Jason Zone, including Kosmoceras jasoni, become increasingly sought after, this fossil stands as both a display-worthy specimen and a scientifically notable addition to any collection.

Key Features

• Species: Kosmoceras jasoni
• Age: Callovian Stage, Jurassic (~166–163 million years old)
• Biozone: Jason Zone
• Locality: Wiltshire, United Kingdom
• Notable Traits: Bold ribbing, tubercles, and distinctive shell ornamentation
• Authenticity: 100% genuine with Certificate of Authenticity
• Exact Specimen: The fossil shown is the one you will receive

This exceptional Kosmoceras jasoni ammonite fossil offers both scientific significance and striking natural beauty, making it a superb choice for collectors, educators, or enthusiasts of Jurassic paleontology.