Description
Genuine Aulacothyris bernardina Brachiopod Fossil
This carefully chosen specimen is a genuine Aulacothyris bernardina brachiopod fossil from the Oxford Clay Formation at Woodham Brickworks, Oxford, Oxfordshire, UK. Dating to the Callovian Stage of the Middle Jurassic, it represents a marine animal that inhabited the seas covering southern and central England more than 160 million years ago.
Brachiopods are an ancient group of marine invertebrates with two mineralised valves enclosing the soft body. Although they can superficially resemble bivalve molluscs, brachiopods belong to a separate animal phylum and have a distinctly different internal anatomy and shell arrangement. In most brachiopods, each individual valve is bilaterally symmetrical, whereas the opposing left and right valves of a typical bivalve are more commonly mirror images of one another.
Aulacothyris bernardina is a terebratulide brachiopod, part of a long-lived group characterised by a compact shell and a specialised internal feeding structure. Its accurately recorded species, formation, geological stage and locality make this a particularly appealing specimen for collectors of British Jurassic fossils and scientifically labelled historical material.
Brachiopod Shell and Morphology
The shell of Aulacothyris bernardina consists of two unequal valves composed primarily of calcium carbonate. These are traditionally described as the ventral or pedicle valve and the dorsal or brachial valve. The pedicle valve generally contains an opening near the beak through which a fleshy anchoring structure, known as the pedicle, could extend.
Inside the living animal, a coiled feeding organ called the lophophore was supported by delicate skeletal structures. The lophophore carried numerous fine tentacles and generated water currents, allowing suspended organic particles to be filtered from the surrounding seawater. This made the brachiopod a stationary suspension feeder rather than an actively moving predator.
Depending on the individual specimen and its preservation, features may include the natural outline of the shell, the beak region, valve curvature, the commissure where the two valves met and subtle growth lines produced as the shell enlarged. Natural areas of wear, mineralisation, clay matrix, compression or incomplete shell are normal characteristics of an authentic Oxford Clay fossil and reflect its long geological history.
Oxford Clay Formation Geology
The Oxford Clay Formation is one of Britain’s best-known fossil-bearing Jurassic rock units. It extends across a broad area of southern and eastern England and is predominantly composed of grey silicate mudstone and claystone, with occasional silty horizons and beds or nodules of argillaceous limestone. The formation spans the Callovian and part of the succeeding Oxfordian Stage.
This specimen is recorded from the Middle Jurassic Callovian portion of the formation. During that time, the Oxford region lay beneath a substantial marine sea. Fine clay and organic material settled through the water onto a relatively low-energy seabed, gradually burying the shells and skeletal remains of marine organisms.
The fine-grained sediment helped preserve an exceptionally varied fossil assemblage. Oxford Clay fossils can include ammonites, belemnites, brachiopods, bivalves, gastropods, crustaceans, fish and marine reptiles. Brachiopods formed part of the benthic community living on or immediately above the sediment-covered sea floor.
Life in the Callovian Sea
The Callovian Stage forms the youngest major division of the Middle Jurassic. At the time this brachiopod lived, Britain consisted of areas of low-lying land separated and surrounded by warm marine environments. The Oxford Clay sea supported complex food webs ranging from microscopic plankton to large predatory marine reptiles.
As a filter-feeding animal, Aulacothyris bernardina occupied a very different ecological role from the mobile ammonites, belemnites, fish and reptiles found within the same formation. Its lophophore extracted food particles from seawater, while its pedicle probably helped maintain a stable position on the seabed or on a firm object.
After death, the shell became buried in soft marine sediment. Continued accumulation compressed the sediment, while chemical and geological processes transformed the surrounding mud into rock. Later extraction of the Oxford Clay for brickmaking exposed fossil-bearing layers that had remained concealed for millions of years.
Woodham Brickworks, Oxford
Woodham Brickworks was one of the clay-working localities that exposed the Oxford Clay Formation around Oxford. Brick pits provided important temporary windows into Jurassic strata, allowing fossils to be recovered from beds that were otherwise hidden beneath soil and younger deposits.
Specimens with a precise historic brickworks provenance are increasingly desirable because many former pits have been filled, landscaped, flooded or are no longer accessible. The Woodham Brickworks locality therefore adds important geographical and historical context to this individual brachiopod.
The combination of a species-level identification, classic British formation and named Oxford locality makes this fossil suitable for collections focused on brachiopods, Oxfordshire geology, Middle Jurassic palaeontology, historic quarry specimens or British marine fossils.
Authentic Fossil and Certificate of Authenticity
This is a genuine fossil specimen and not a replica, cast or manufactured reproduction. Its form, colour, texture and preservation are the result of the original brachiopod shell and the natural processes of burial, mineralisation and geological weathering.
The photograph shows the actual carefully chosen specimen you will receive. Please examine the supplied images closely, as they provide the best record of its precise condition, preservation, matrix and individual appearance.
Full sizing please see photo.
The fossil includes a generic Certificate of Authenticity card supported by our lifetime guarantee of authenticity. It is an excellent addition to a British fossil collection, brachiopod display, geological cabinet, educational collection or Middle Jurassic marine-life exhibit.
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