Iridescent Psiloceras Ammonite Fossil Jurassic Watchet Somerset UK Blue Lias Specimen

Description

Iridescent Psiloceras Ammonite Fossil from Doniford Bay, Somerset

This beautiful fossil specimen is an iridescent ammonite belonging to the genus Psiloceras, discovered within the Blue Lias Formation at Doniford Bay near Watchet, Somerset, United Kingdom. The fossil displays natural iridescence across the preserved shell surface, a striking effect created by the preservation of the original shell layers that refract light into shimmering colours.

Your specimen was discovered by our own team members, Alister and Alison, on 28 February 2026 along the Somerset coastline. Following discovery, the fossil was carefully cleaned, prepared, and treated by Alison, ensuring the delicate shell structure and iridescent surfaces were preserved while stabilising the fossil for display.

The photographs in this listing show the exact specimen you will receive, making this a unique collectible example of a Jurassic ammonite. The fossil is a genuine specimen and includes a Certificate of Authenticity with a lifetime guarantee card confirming its authenticity.

Full sizing of the specimen can be seen in the listing photographs.

Geological Origin – Blue Lias Formation, Somerset

This ammonite originates from the Blue Lias Formation, one of the most famous Lower Jurassic rock sequences in the United Kingdom. These rocks were deposited approximately 201–190 million years ago during the Early Jurassic Period.

The Blue Lias is composed of alternating limestone and shale layers formed within a shallow marine basin that covered much of southern Britain at the time. Sediment settled slowly on the seabed, preserving the remains of marine organisms that lived in the Jurassic seas.

Doniford Bay near Watchet is a particularly productive fossil locality where coastal erosion exposes fossil-rich layers of Blue Lias. The site regularly yields well-preserved marine fossils including:

• Ammonites
• Belemnites
• Bivalves and gastropods
• Crinoids and echinoderms
• Marine reptiles such as ichthyosaurs

These deposits provide an important record of marine life during the earliest stages of the Jurassic Period.

Psiloceras – Early Jurassic Ammonite

The genus Psiloceras is one of the earliest ammonite groups to appear after the end-Triassic mass extinction. It belongs to the family Psiloceratidae, a group of ammonites that rapidly diversified during the earliest Jurassic.

Taxonomic classification:

• Phylum: Mollusca
• Class: Cephalopoda
• Subclass: Ammonoidea
• Order: Ammonitida
• Superfamily: Psiloceratoidea
• Family: Psiloceratidae
• Genus: Psiloceras

Species of Psiloceras are extremely important in geology because they serve as index fossils for the Hettangian Stage, the earliest subdivision of the Jurassic Period. Their distinctive shells allow geologists to identify and date rock layers with precision.

Morphology and Shell Characteristics

Ammonites were marine cephalopods closely related to modern squid, cuttlefish, and octopus. They possessed a coiled external shell divided into internal chambers, which helped regulate buoyancy and allowed the animal to move vertically through the water column.

Characteristic features of Psiloceras ammonites include:

• A smooth, gently rounded shell lacking strong ribbing
• A tightly coiled planispiral shell structure
• Fine growth lines visible across the shell surface
• Simple ammonitic suture patterns along the chamber walls
• A relatively compressed shell profile

This specimen exhibits natural iridescent shell preservation, caused by the survival of microscopic layers of the original aragonite shell. When light passes through these thin layers, it produces shimmering colours similar to those seen in mother-of-pearl.

Iridescent ammonite shells from the Blue Lias are particularly prized because the original shell material is rarely preserved.

Early Jurassic Marine Environment

During the Early Jurassic, the seas covering Somerset supported a rich and diverse marine ecosystem. Ammonites such as Psiloceras were among the most abundant and widespread marine organisms of the time.

These animals likely lived as active swimmers, using jet propulsion to move through the water while hunting small marine organisms such as crustaceans and plankton.

The surrounding ecosystem included:

• Ammonites and belemnites
• Marine reptiles including ichthyosaurs
• Bivalves and gastropods
• Echinoderms such as crinoids

When these animals died, their shells settled to the seabed where they could become buried in fine sediment, allowing fossilisation within the limestone layers.

Authentic Jurassic Fossil Discovered by Our Team

This fossil represents a genuine ammonite specimen discovered directly from the fossil-rich coastline of Somerset. Fossils collected and prepared by experienced collectors from classic British localities are especially valued by collectors.

Key features of this specimen include:

• Genuine Psiloceras ammonite fossil
• Naturally iridescent shell preservation
• From the Blue Lias Formation
• Early Jurassic Period
• Collected at Doniford Bay, Watchet, Somerset, UK
• Discovered by Alister and Alison on 28 February 2026
• Cleaned, prepared, and treated by Alison
• Photographs show the exact fossil specimen you will receive
• Supplied with a Certificate of Authenticity and lifetime guarantee

This remarkable iridescent ammonite makes an excellent addition to Jurassic fossil collections, ammonite displays, geology collections, and natural history exhibits, offering a beautiful example of marine life from the earliest Jurassic seas of Somerset.