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 is a fascinating specimen from the Llanvirn Series of the Ordovician Period, discovered in the Upper Gilwern Quarry, Wales, UK. Dated to around 465 million years ago, this fossil offers a remarkable glimpse into early marine life when trilobites dominated the prehistoric seas.

This particular specimen was discovered by our own team members, Alister and Alison, on 2 April 2024, and meticulously cleaned, prepped, and treated by Alison to ensure it retains its natural integrity and detail. The photo shows the exact specimen you will receive, accompanied by a 1 cm scale cube for reference. The fossil comes with a Certificate of Authenticity, confirming its provenance and genuine geological heritage.

Geological Context and Formation

The fossil originates from the Llanvirn Series, part of the Middle Ordovician, approximately 470–458 million years ago. During this era, what is now Wales lay beneath a warm, shallow sea on the ancient microcontinent Avalonia, positioned in the southern hemisphere. Sediments accumulated over time, forming fine-grained mudstones and siltstones in which countless marine organisms, including trilobites, were buried and preserved.

The Upper Gilwern Quarry is part of the Bala Group, known for its fossil-rich shale layers that preserve delicate exoskeletal details. The depositional environment was offshore marine, likely within low-energy, oxygen-deficient waters. These conditions limited scavenging and bacterial decay, creating the perfect environment for fossilisation.

This geological sequence is significant in British palaeontology, helping scientists understand Ordovician ecosystems and faunal succession. The presence of Ogyginus within these beds marks an important biostratigraphic indicator, used to correlate Ordovician strata across Europe and North America.

Taxonomy and Classification

• Phylum: Arthropoda

• Class: Trilobita

• Order: Asaphida

• Family: Asaphidae

• Genus: Ogyginus (Murchison, 1839)

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

• Locality: Upper Gilwern Quarry, Wales, United Kingdom

The genus Ogyginus was formally described by Sir Roderick Murchison in 1839, one of Britain’s most notable geologists. Fossils of Ogyginus are among the defining elements of Ordovician assemblages in the Caradoc and Llanvirn stages, making them valuable both scientifically and historically.

Morphological Features and Preservation

This partial trilobite fossil preserves the cephalon (head shield) and part of the thoracic segments, displaying the smooth and rounded morphology typical of the genus Ogyginus. Members of this genus are noted for their broad, flattened body shape, well-developed glabella, and lack of eyes—a trait suggesting adaptation to low-light or deep-sea environments.

The fossil’s exoskeleton is smooth and gently curved, reflecting the animal’s benthic lifestyle as a slow-moving seafloor dweller. The absence of spines and streamlined shape imply that Ogyginus was well adapted for crawling through soft marine sediment in search of organic material or detritus. The specimen retains fine surface textures and subtle relief features, accentuated by careful professional preparation.

The matrix surrounding the fossil is a fine-grained Ordovician mudstone, offering an attractive natural contrast that highlights the trilobite’s form. The fossil is securely mounted on a custom display stand, making it ideal for scientific study or display.

Palaeoenvironment and Ecology

During the Ordovician, the Welsh Basin was a thriving marine habitat teeming with diverse life forms such as graptolites, brachiopods, nautiloids, and early echinoderms. Trilobites like Ogyginus occupied the benthic zone, feeding on detritus and small organic particles. The lack of complex eyes in Ogyginus indicates a subdued-light environment, possibly the deeper reaches of the shelf or slope.

The region’s sedimentary record captures periodic influxes of volcanic ash and fine clay, which would have rapidly buried seafloor organisms, aiding in their exceptional preservation. Such conditions created the fossil-rich shale layers characteristic of the Llanvirn sequence in Wales.

Scientific and Collector Significance

This Ogyginus trilobite fossil represents a classic example of Ordovician British palaeontology, offering insight into early arthropod evolution and palaeoecology. As a member of the Asaphidae family, Ogyginus illustrates the adaptability and diversity of trilobites during one of the most biologically productive periods in Earth’s history.

For collectors, researchers, or educational institutions, this specimen provides a tangible connection to the deep past—a direct link to life in the ancient seas that once covered Wales. Professionally prepared and displayed, it is both a scientific artefact and a natural work of art.

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.