Description
Genuine Middle Jurassic Button Coral Fossil
This carefully chosen specimen is a genuine scleractinian coral fossil, commonly described as a button coral, from the Hampen Marly Formation of the Great Oolite Group. It was collected from Stocky Bank at Stonesfield, Oxfordshire, UK, and dates to the Bathonian Stage of the Middle Jurassic Period.
Approximately 166 to 168 million years old, this fossil represents a marine coral that lived when warm, shallow seas covered much of southern and central England. It belongs to the order Scleractinia, the major group of stony corals whose members construct rigid calcium carbonate skeletons. Scleractinian corals first appeared during the Triassic Period and became important components of many later Mesozoic marine communities.
The descriptive name “button coral” refers to the specimen’s compact, rounded or low conical form. This shape gives the fossil an attractive, recognisable appearance and makes it a distinctive addition to a collection of British Jurassic fossils, fossil corals or Great Oolite Group specimens.
Scleractinian Coral Morphology
The hard skeleton produced by an individual coral animal is known as a corallum. Its upper surface contains a central skeletal cup, or calice, which housed the soft-bodied coral polyp during life. Radiating inward from the outer wall are thin vertical partitions called septa, producing the characteristic star-like pattern associated with many fossil and living stony corals.
Depending on its orientation and preservation, this specimen may display a rounded outline, radial septa, the central calice, growth markings or part of the outer wall. The underside may preserve an attachment surface or basal structure that helped the coral remain stable on the Jurassic seabed.
During life, the polyp occupied the upper part of the skeleton and extended tentacles into the surrounding seawater. These were used to capture microscopic food particles and small planktonic organisms. The skeleton grew gradually beneath the animal as successive layers of calcium carbonate were deposited.
Button-shaped solitary corals were well suited to life on shallow marine substrates. Their relatively low profile could provide stability in environments affected by currents, waves and shifting carbonate sediment. The precise form of an individual coral was influenced by its growth stage, original position, sediment conditions and the degree of exposure to moving water.
Hampen Marly Formation Geology
The Hampen Marly Formation forms part of the Great Oolite Group, a major succession of Middle Jurassic sedimentary rocks found across the Cotswolds and neighbouring parts of southern England. These rocks record the repeated advance and retreat of shallow seas across the region during the Bathonian Stage.
The formation includes marly limestone, calcareous mudstone and related carbonate-rich sediments. Marl is a mixture of clay and calcium carbonate, reflecting deposition in an environment that received both fine terrestrial sediment and biologically produced marine carbonate material.
Changes between limestone-rich and muddier beds record variations in water depth, current strength, sediment supply and biological productivity. At times the seabed supported abundant marine communities, while quieter intervals allowed fine mud and carbonate particles to settle through the water column.
The coral was eventually buried by sediment, protecting part of its skeleton from destruction. Over millions of years, the surrounding material was compacted and cemented into rock. Mineral-rich groundwater moved through the sediment and contributed to the preservation of the coral’s original form and skeletal features.
Bathonian Marine Environment
During the Bathonian Stage, the area now occupied by Oxfordshire lay within a broad, warm, shallow marine environment. Britain was positioned farther south than it is today and experienced a climate capable of supporting extensive carbonate-producing ecosystems.
The Great Oolite seas contained a diverse range of organisms, including corals, brachiopods, bivalves, gastropods, echinoids, crinoids, ammonites and other marine invertebrates. Fish and marine reptiles occupied higher levels of the food web, while numerous smaller animals lived on, within or immediately above the seabed.
Scleractinian corals contributed hard skeletal material to these carbonate environments. Solitary corals lived independently rather than forming the extensive joined colonies produced by colonial genera. Each individual consisted of a single polyp housed within its own calcareous skeleton.
Following death, the soft tissues decayed and the empty corallum remained on the sea floor. It may have been moved, overturned or partly worn before final burial. These natural processes can produce variations in surface detail, incomplete margins, attached matrix and differences in colour across an authentic fossil specimen.
Stonesfield and Stocky Bank Provenance
Stonesfield is an important Middle Jurassic locality in Oxfordshire and is well known in the history of British geology and palaeontology. The surrounding area contains several fossil-bearing units associated with the Great Oolite succession, preserving evidence of the varied environments that existed during the Bathonian.
Stocky Bank provides a precise locality for this specimen, giving it stronger geological and collection value than a fossil recorded only from a broad regional source. Detailed provenance connects the fossil directly to the geology of Oxfordshire and allows it to be placed accurately within the wider history of Britain’s Middle Jurassic seas.
This combination of a recognised fossil type, named formation, geological group, stage and locality makes the specimen particularly suitable for collectors interested in fossil corals, Oxfordshire geology, British palaeontology, Great Oolite fossils or ancient marine ecosystems.
Authentic Fossil with Certificate of Authenticity
This is a genuine natural fossil and not a replica, cast or manufactured reproduction. Its shape, texture, colour and preservation result from the original scleractinian coral skeleton and the geological processes it experienced over millions of years.
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, preserved features, 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 would make an attractive addition to a British fossil collection, coral display, geological cabinet, educational collection or Middle Jurassic natural-history exhibit.
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