Description
Kosmoceras jasoni Ammonite Fossil – Jurassic of Wiltshire, UK
This listing offers a genuine Kosmoceras jasoni ammonite fossil from the Upper Callovian Stage of the Middle Jurassic, discovered in Wiltshire, United Kingdom. A carefully selected specimen, this ammonite demonstrates the distinctive ribbing and shell structure typical of the species. It comes with a Certificate of Authenticity, ensuring both its provenance and its value as a true piece of natural history. The photos show the actual fossil you will receive, with a 1 cm scale cube included for precise sizing.
Geological Age and Provenance
The fossil originates from the Upper Callovian Stage (approximately 164–161 million years ago), part of the Middle Jurassic period. The Callovian represents an interval of widespread shallow marine environments across Europe, where conditions were ideal for ammonites to flourish. Wiltshire, in southern England, is particularly renowned for its Jurassic deposits, providing fossils that are both scientifically significant and highly collectible.
Scientific Classification
- Kingdom: Animalia
- Phylum: Mollusca
- Class: Cephalopoda
- Order: Ammonitida
- Superfamily: Stephanoceratoidea
- Family: Kosmoceratidae
- Genus: Kosmoceras
- Species: Kosmoceras jasoni
The genus Kosmoceras is one of the most iconic ammonite groups of the Jurassic, with K. jasoni being a key species for biostratigraphy in the Upper Callovian. Its distinctive shell features make it an essential reference fossil for geologists and paleontologists.
Morphological Features
Kosmoceras jasoni is recognized by its strongly ribbed and often ornate shell, featuring bifurcating ribs that run across the flanks and reach the venter. The ribs are typically sharp and prominent, giving the ammonite a strikingly sculptural quality. Some specimens also show tuberculation (small nodes or tubercles) along the ribs, a feature that adds further detail to the fossil’s surface. The whorls are generally tightly coiled and involute, with the inner whorls partly concealed by later growth. These features made the species easily identifiable and visually impressive, particularly in larger, well-preserved examples.
Paleoenvironment and Scientific Importance
During the Upper Callovian, the region that is now Wiltshire was submerged beneath warm epicontinental seas rich in marine life. Ammonites like Kosmoceras jasoni thrived in these waters, feeding on smaller marine organisms while themselves forming part of the food chain for marine reptiles and fish. As a member of the Kosmoceratidae, K. jasoni is highly important as an index fossil, enabling precise dating and correlation of Jurassic strata across Europe. Its presence marks the Jason Zone, a key subdivision of the Callovian, making it crucial in geological mapping and research.
Collector and Display Value
This specimen of Kosmoceras jasoni is more than a fossil – it is a tangible link to the Jurassic seas of Britain. With its defined ribbing and iconic form, it serves both as an impressive display piece and as a scientifically valuable reference. Collectors of British ammonites, students of paleontology, and natural history enthusiasts alike will appreciate the rarity and beauty of this ammonite.
Key Features
- Genuine Kosmoceras jasoni ammonite fossil from Wiltshire, UK.
- Geological age: Upper Callovian, Middle Jurassic (c. 164–161 million years ago).
- Distinct ribbing and sculptural shell form, characteristic of the species.
- Important index fossil, marking the Jason Zone of the Callovian.
- Supplied with a Certificate of Authenticity.
This Kosmoceras jasoni ammonite fossil is an outstanding addition to any collection, combining scientific significance with striking natural beauty, and offering a true piece of Britain’s Jurassic heritage.
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