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

Authentic British Trilobite (Ogyginus) Partial Fossil from Wales

This genuine British Trilobite (Ogyginus) Partial Fossil with Stand originates from the Upper Gilwern Quarry, Wales, UK, dating to the Llanvirn Series of the Middle Ordovician Period, approximately 465 million years ago. This fossil captures a remarkable moment in early marine evolution, preserving one of Britain’s most iconic Ordovician trilobites.

Your specimen was discovered by our own field team members, Alister and Alison, on 2 April 2024, and has been carefully cleaned, prepped, and treated by Alison to reveal its natural detail and ensure long-term preservation. The photo shows the actual fossil you will receive, and a 1 cm scale cube is included for accurate sizing. The fossil comes with a Certificate of Authenticity, verifying it as a genuine specimen from a scientifically important locality.

Geological Background and Formation

The Llanvirn Series, part of the Middle Ordovician, represents a period of significant biological diversification known as the Great Ordovician Biodiversification Event. During this time, the area now known as Wales was positioned near the equator on the ancient microcontinent Avalonia and was covered by warm, shallow seas teeming with trilobites, brachiopods, graptolites, and other marine organisms.

The Upper Gilwern Quarry, a classic Welsh fossil site, exposes the Bala Group, a geological formation consisting mainly of dark mudstones and siltstones. These sediments were deposited in a low-energy offshore marine environment, where fine mud accumulated slowly on the seabed. Periodic underwater landslides and rapid sedimentation events caused organisms on the sea floor to be quickly buried, protecting them from decay and scavenging.

As a result, fossils from this formation are often well-preserved, showing exceptional morphological detail. The Llanvirn rocks of the quarry have been extensively studied for their biostratigraphic importance, helping to define key zones of the Ordovician biosequence across Britain and Europe.

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, one of the founders of British geology. It remains an important index fossil for the Ordovician period and is commonly used in biostratigraphic correlation of marine sediments. The species is notable for its smooth, rounded exoskeleton and its lack of eyes—a unique feature among trilobites that indicates adaptation to deeper, darker marine environments.

Morphological Description and Preservation

This partial trilobite fossil includes the cephalon (head shield) and part of the thoracic segments, showcasing the characteristic features of the genus Ogyginus. The cephalon is broad and semi-circular with a gently convex glabella (the central lobe), bordered by distinct furrows and fine detail visible along the exoskeleton. The surface is smooth, consistent with Ogyginus’s benthic lifestyle, and exhibits faint segmentation that hints at its multi-lobed structure.

Members of this genus lacked compound eyes, suggesting that they inhabited low-light or sediment-covered environments, possibly scavenging detritus from the sea floor. Their broad, flattened body form allowed them to burrow slightly into soft mud for feeding or protection.

This specimen’s preservation is exceptional for its locality, with clear definition of the exoskeletal ridges and natural mineral infill that highlights the fossil’s contours. It is presented on a solid piece of original matrix, creating a visually striking contrast that enhances its scientific and display value. The fossil is securely mounted on a custom display stand, ideal for both collectors and educational settings.

Palaeoenvironment and Significance

The Upper Gilwern Quarry fossils provide valuable insights into the Ordovician marine ecosystem of Avalonia. The sea floor during this time was covered with fine silts and clays, supporting a diverse community of trilobites, brachiopods, bryozoans, and early echinoderms. The absence of eyes in Ogyginus suggests it lived in deeper waters below the photic zone, possibly where turbidity limited sunlight penetration.

This depositional setting produced finely laminated mudstones, now known as black shales, which record periods of low oxygen and rapid sedimentation—ideal for fossil preservation. These conditions allowed for the delicate preservation of trilobite shells and provide a unique window into Ordovician biodiversity.

Collector and Display Value

This Ogyginus trilobite fossil is not only a piece of British geological history but also a scientific specimen representing one of the earliest complex marine arthropods. Professionally prepared and presented, it combines aesthetic appeal with educational significance. Mounted on a quality display stand, it serves as an impressive centrepiece for fossil collections, classrooms, or home displays.

Discovered, prepared, and verified by our own field team, this fossil connects you directly to a world that existed 465 million years ago, in the ancient seas that once covered Wales.

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.