Psiloceras Ammonite Fossil Jurassic Blue Lias Watchet Somerset UK Specimen

Description

Psiloceras Ammonite Fossil from the Blue Lias of Doniford Bay

This authentic fossil specimen is an ammonite belonging to the genus Psiloceras, recovered from the famous Blue Lias Formation at Doniford Bay near Watchet, Somerset, United Kingdom. These ammonites lived during the Early Jurassic Period, shortly after the end-Triassic extinction event, when new marine ecosystems began to flourish across the world’s oceans.

The fossil offered here was discovered by our own team members, Alister and Alison, on 28 February 2026 along the Somerset coastline. After recovery, the specimen was carefully cleaned, prepared, and treated by Alison to stabilise the fossil and reveal its natural shell detail while preserving the integrity of the specimen.

The photographs in the listing show the exact fossil specimen you will receive, making this a unique addition to any fossil collection. This fossil is a genuine ammonite specimen and includes a Certificate of Authenticity with a lifetime guarantee card.

Full sizing can be seen in the listing photographs.

Geological Origin – Blue Lias Formation, Somerset

This ammonite fossil originates from the Blue Lias Formation, one of the most famous Lower Jurassic rock units in the United Kingdom. The Blue Lias consists of alternating layers of limestone and shale, deposited in a shallow marine environment approximately 201–190 million years ago.

During the Early Jurassic, the region that is now Somerset lay beneath a warm, shallow epicontinental sea connected to the wider Tethys Ocean. Sediment slowly accumulated on the seabed, burying the remains of marine organisms and allowing them to fossilise within the limestone layers.

Doniford Bay near Watchet is a well-known fossil locality where coastal erosion regularly exposes new fossil material from the Blue Lias cliffs and foreshore. The site yields a wide range of Early Jurassic fossils including:

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

These deposits are particularly important for preserving early Jurassic ammonite species used in biostratigraphic zonation of Jurassic rocks.

Psiloceras – Early Jurassic Index Ammonite

The genus Psiloceras is one of the earliest ammonite groups to appear after the end-Triassic extinction event and is widely recognised as a key index fossil for the earliest Jurassic stages.

Taxonomic classification:

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

Species of Psiloceras are used by geologists worldwide to identify the Hettangian Stage, the earliest subdivision of the Jurassic Period. Their widespread distribution and rapid evolutionary changes make them particularly valuable for correlating rock layers across different regions.

Morphology and Shell Structure

Ammonites were marine cephalopods related to modern squid, octopus, and cuttlefish. They possessed a coiled external shell divided internally into chambers, which helped regulate buoyancy while swimming.

Characteristic features of Psiloceras ammonites include:

• A smooth, rounded shell with minimal ornamentation
• A tightly coiled planispiral shell structure
• Fine growth lines marking shell expansion
• A relatively compressed whorl profile
• Simple suture patterns typical of early Jurassic ammonites

The shell consisted primarily of aragonite, a calcium carbonate mineral that formed layered shell walls. In some specimens, portions of this shell material are preserved, providing fine surface detail.

Early Jurassic Marine Environment

During the Early Jurassic, marine ecosystems around what is now Somerset were thriving with diverse life forms. The seas supported a rich variety of organisms, including both invertebrates and marine reptiles.

The marine environment surrounding Psiloceras ammonites included:

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

Ammonites were active swimming predators or scavengers that used jet propulsion to move through the water column while hunting small prey.

Their shells provided buoyancy control, allowing them to occupy different depths within the water column.

Authentic Jurassic Fossil Discovered by Our Team

This fossil represents a genuine specimen discovered and prepared by experienced fossil collectors along the Jurassic coastline of Somerset. Fossils collected directly from well-known British fossil localities are especially valued by collectors and enthusiasts.

Key features of this specimen include:

• Genuine Psiloceras ammonite fossil
• 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 ammonite makes an excellent addition to Jurassic fossil collections, ammonite displays, geology collections, and educational natural history exhibits, providing a beautiful example of marine life from the earliest Jurassic seas of the United Kingdom.