Rare Cadoceras sublaev Fossil Ammonite Lower Callovian Jurassic Ashton Keynes Wiltshire UK Genuine Specimen with Certificate of Authenticity

Description

Exquisite Cadoceras sublaev Ammonite from the Lower Callovian, Wiltshire, UK

This outstanding Cadoceras sublaev fossil ammonite originates from the Lower Callovian Stage of the Middle Jurassic Period, approximately 166–163 million years ago, and was discovered near Ashton Keynes, Wiltshire, United Kingdom. The specimen represents an elegant and scientifically significant ammonite from the classic Oxford Clay–Callovian succession of southern England, a formation world-renowned for yielding beautifully preserved marine fossils that document the rich diversity of Jurassic seas.

Geological and Depositional Context

During the Callovian Stage, much of southern Britain lay beneath a shallow epicontinental sea. The sediments deposited here formed the Oxford Clay and associated formations, composed predominantly of fine-grained mudstones and marls. These anaerobic marine conditions were ideal for fossil preservation, protecting delicate ammonite shells from dissolution and scavenging. Ashton Keynes lies within a well-documented paleontological region, where the Callovian strata record one of the key intervals in ammonite evolution and diversification within the Boreal faunal province.

The fossil-bearing layers from this locality represent a calm, offshore depositional environment that favoured the preservation of complete and often finely ornamented shells like those of Cadoceras species.

Species Overview – Cadoceras sublaev

The genus Cadoceras belongs to the family Cardioceratidae, superfamily Stephanoceratoidea, order Ammonitida. Cadoceras sublaev is distinguished by its moderately involute shell, rounded whorls, and gently ribbed flanks that typically fade towards the umbilicus. The species name “sublaev” refers to the relatively smooth or subdued ribbing compared to other members of the genus. These morphological features suggest it was an active, free-swimming predator within the mid-water column, using jet propulsion to navigate the Jurassic seas.

This species holds particular importance within the Lower Callovian Cadoceras elatmae Biozone, serving as an index fossil for stratigraphic correlation across Europe. Fossils of Cadoceras sublaev are relatively uncommon compared to other ammonites of the period, making this specimen a valuable addition for collectors and researchers alike.

Paleontological and Scientific Importance

Cadoceras sublaev exemplifies the evolutionary transition from the more heavily ornamented Erymnoceras forms of the early Callovian to the smoother morphologies of later Cardioceratids. Its presence within the Ashton Keynes deposits indicates deposition within the Subboreal marine province, an area that recorded extensive faunal interchange between northern and southern Jurassic seas. These fossils provide key evidence for paleoenvironmental reconstructions and for understanding biogeographic distribution patterns during the Middle Jurassic.

Condition and Authenticity

This is a 100% genuine fossil ammonite, carefully selected for its excellent preservation and display quality. The surface exhibits fine natural details that highlight the distinctive coiling and ribbing typical of Cadoceras sublaev. The fossil has been gently cleaned and stabilised to preserve its integrity without artificial enhancement. The photograph shows the actual specimen you will receive, ensuring complete transparency and authenticity.

A Certificate of Authenticity is included, verifying the fossil’s identification, geological age, and locality.

Details at a Glance

• Species: Cadoceras sublaev
• Family: Cardioceratidae
• Superfamily: Stephanoceratoidea
• Order: Ammonitida
• Age: Lower Callovian Stage, Middle Jurassic (~166–163 million years ago)
• Formation: Oxford Clay / Callovian deposits
• Locality: Ashton Keynes, Wiltshire, United Kingdom
• Condition: Natural, genuine fossil; carefully cleaned and prepared
• Scale: Cube = 1 cm (see photo for full sizing)
• Included: Certificate of Authenticity

A Distinctive Collector’s Fossil

This Cadoceras sublaev ammonite embodies both scientific significance and natural beauty. Its smooth, elegant form reflects the evolutionary refinement of Jurassic ammonites, while its origin from the storied clay deposits of southern England adds historical and geological depth. A rare opportunity to own a genuine piece of Britain’s Jurassic heritage, perfectly suited for collectors, educators, and enthusiasts of natural history.