British Trilobite Ogyginus Fossil Partial Impression with Stand – Llanvirn Series, Ordovician, Upper Gilwern Quarry, Wales, UK

Authentic British Trilobite (Ogyginus) Partial Impression Fossil from Wales

This genuine British Trilobite (Ogyginus) Fossil Partial Impression with Stand originates from the Upper Gilwern Quarry, located in Wales, UK, and dates to the Llanvirn Series of the Middle Ordovician Period, approximately 465 million years ago. This remarkable specimen captures the detailed impression of one of Britain’s most iconic Ordovician trilobites, preserved naturally in fine sedimentary rock.

Your specimen was discovered by our own team members, Alister and Alison, on 2 April 2024, and has been expertly cleaned, prepped, and treated by Alison to reveal its intricate fossilised impression while maintaining the authenticity of its matrix. The photo shows the exact specimen you will receive, and a 1 cm scale cube is included for accurate sizing. The fossil is presented on a custom display stand and comes complete with a Certificate of Authenticity, confirming its provenance and preparation quality.

Geological Background and Formation

The Llanvirn Series forms part of the Middle Ordovician, a period that witnessed the rapid diversification of marine life during the Great Ordovician Biodiversification Event. During this time, the area that is now Wales was located in the southern hemisphere as part of the ancient microcontinent Avalonia, covered by warm, shallow seas teeming with marine organisms such as trilobites, brachiopods, graptolites, and cephalopods.

The Upper Gilwern Quarry exposes layers of the Bala Group, a formation composed mainly of mudstones and siltstones. These rocks were deposited in a quiet offshore marine environment, where slow sedimentation allowed for exceptional fossil preservation. Periodic underwater landslides or rapid burial events trapped and preserved organisms in fine mud, preventing decay and scavenging.

Over millions of years, these muds compacted into rock, leaving impressions (mould fossils) of the once-living trilobites. This fossil is one such natural impression, recording the outline and surface features of Ogyginus with geological precision—a natural cast from the Ordovician seabed itself.

Taxonomy and Classification

• Phylum: Arthropoda

• Class: Trilobita

• Order: Asaphida

• Superfamily: Asaphoidea

• Family: Asaphidae

• Genus: Ogyginus (Murchison, 1839)

• Geological Stage: Llanvirn Series, Middle Ordovician (~465 million years ago)

• Locality: Upper Gilwern Quarry, Wales, UK

The genus Ogyginus was first described by Sir Roderick Impey Murchison in 1839, a founding figure of British geology and the author of The Silurian System. Ogyginus is among the most recognisable trilobites of the British Ordovician and is used as a biostratigraphic marker for correlating geological layers across Europe and beyond.

Morphology and Fossil Characteristics

This specimen preserves a partial impression fossil, meaning it records the fine external features of the trilobite’s exoskeleton, pressed naturally into the ancient sea-floor sediment. The fossil reveals parts of the cephalon (head shield) and thoracic segments, showing the smooth, rounded form characteristic of the genus Ogyginus.

Unlike many trilobites, Ogyginus lacked compound eyes, an evolutionary trait suggesting it inhabited low-light or deeper marine environments. Its wide, flattened body allowed it to move easily over soft seafloor muds, while its smooth surface hints at a benthic detritivore lifestyle, feeding on organic matter on the seabed.

This partial impression highlights the fine textural details of the original organism, including subtle segmentation, curvature, and glabellar shape. The surrounding sediment matrix is composed of fine Ordovician mudstone, creating a natural visual contrast that enhances the fossil’s display quality. The specimen’s preparation has preserved the natural patina of the matrix while stabilising the fossil for long-term preservation.

Palaeoenvironment and Geological Importance

The Ordovician seas of Avalonia were dynamic, hosting an abundance of early arthropods, molluscs, and echinoderms. The trilobite Ogyginus thrived in this environment, well adapted to life on soft marine sediments. Fossils from the Upper Gilwern Quarry are particularly significant because they record the faunal communities of the Welsh Basin, providing valuable insight into Ordovician marine ecosystems and evolutionary patterns.

These mudstones are known for their excellent preservation potential, often capturing detailed impressions of soft-bodied organisms alongside hard-shelled fossils. The fine laminations and lack of disturbance suggest deposition under low-energy, oxygen-poor conditions—ideal for preserving even delicate trilobite exoskeletons and impressions.

Collector and Display Significance

This Ogyginus trilobite partial impression fossil represents a unique and scientifically valuable example of British palaeontology. As a natural mould formed over 465 million years ago, it preserves the imprint of one of Earth’s earliest complex arthropods, offering a tangible connection to life from deep geological time.

Professionally prepared and mounted on a quality stand, this fossil is ideal for display in a home, educational, or museum setting. It serves as both a scientifically important specimen and a visually appealing natural artefact from the Ordovician seas of Wales.

Discovered and prepared by our in-house team, this piece combines provenance, authenticity, and craftsmanship—an exceptional addition for collectors, educators, or enthusiasts of British geological history.

All of our Fossils are 100% Genuine Specimens and come with a Certificate of Authenticity.
Scale cube = 1 cm – for full sizing, please refer to the photos.