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

Authentic British Trilobite (Ogyginus) Partial Fossil from Wales

This exceptional British Trilobite (Ogyginus) Partial Fossil with Stand was discovered in the Upper Gilwern Quarry, Wales, UK, and dates to the Llanvirn Series of the Middle Ordovician, approximately 465 million years ago. It represents a remarkable specimen of one of Britain’s most iconic Ordovician trilobites, preserved in fine detail and displayed on a professional stand for easy viewing and protection.

The fossil 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 bring out the intricate anatomical features of the trilobite while maintaining its natural integrity. The photo shows the exact specimen you will receive, and a 1 cm scale cube is included for accurate sizing. Every specimen comes with a Certificate of Authenticity, confirming its genuine origin and preparation.

Geological Setting and Historical Context

This specimen originates from the Llanvirn Series, a subdivision of the Middle Ordovician, representing an age of immense biological diversification within marine ecosystems. The Ordovician seas covering what is now Wales were part of the ancient Avalonia microcontinent, located near the equator and bathed in warm, nutrient-rich waters that supported an explosion of early marine life.

The Upper Gilwern Quarry exposures belong to the Bala Group, composed mainly of dark mudstones and fine-grained siltstones. These sediments were deposited in an offshore marine environment, likely below the wave base, where fine mud slowly accumulated on the seafloor. Periodic underwater sediment flows would have rapidly buried marine organisms, such as trilobites, in low-oxygen conditions ideal for fossilisation.

Fossils from this site are scientifically significant, providing insight into the biostratigraphy and palaeoecology of the Ordovician seas of Avalonia. The assemblage, including Ogyginus, is key to defining faunal zones used by geologists for correlating strata across Europe and beyond.

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 formally described by Sir Roderick Impey Murchison in 1839, one of the founding figures of modern geology and author of The Silurian System. Ogyginus is among the most recognisable and widely studied British trilobites, frequently used as an index fossil for Ordovician strata due to its distinct morphology and broad stratigraphic distribution.

Morphological Description

This partial specimen preserves the cephalon (head shield) and part of the thorax, allowing for clear identification. Ogyginus trilobites are characterised by their broad, rounded cephalon with a smooth surface and gently convex glabella. Unlike many trilobites, Ogyginus lacked compound eyes—a trait suggesting it lived in low-light or deeper marine environments. Its thoracic segments were smooth and flattened, allowing it to move efficiently across soft sea-floor muds.

The fossil shows excellent preservation of the exoskeletal surface, with fine details visible under light, including faint segmentation and subtle curvature of the shell. The natural mineralisation of the fossil matrix has created a visually appealing contrast, highlighting the form of the trilobite against its sedimentary background. The specimen is displayed on a custom stand, making it ideal for collectors, educators, or anyone interested in British palaeontology.

Depositional Environment and Palaeoecology

The Ordovician seas of Avalonia were rich ecosystems filled with trilobites, brachiopods, graptolites, and cephalopods. Ogyginus was a benthic detritivore, living on or just below the sediment surface, feeding on organic material deposited on the seafloor. Its broad, smooth exoskeleton would have allowed it to move easily through soft mud, while its lack of eyes implies a reliance on touch and chemical cues rather than sight.

The depositional environment of the Upper Gilwern mudstones was quiet and anoxic, preventing decay and scavenging after burial. This created ideal conditions for the preservation of delicate arthropod fossils, allowing scientists today to study the fine morphological details of these early marine creatures. The mudstones also record subtle sedimentary layering, reflecting variations in Ordovician sea conditions and offering clues to ancient climate and sea-level changes.

Collector and Display Value

This Ogyginus trilobite fossil from Wales is both scientifically valuable and visually captivating. Professionally prepared and mounted, it embodies the quality and historical importance of British Ordovician fossil sites. Its provenance from the Upper Gilwern Quarry, combined with its fine preservation and professional preparation, makes it a museum-quality display piece and a fascinating addition to any fossil collection.

Owning this specimen connects you to an ancient world 465 million years old—a time when trilobites like Ogyginus thrived on the seabed of what would one day become the Welsh hills.

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.