Description
Genuine Jurassic Bryozoan Colony Fossil
This carefully chosen specimen is a genuine indeterminate bryozoan colony fossil from Foss Cross Quarry near Cirencester in Gloucestershire, UK. It originates from the Great Oolite Group and dates from the Bathonian Stage of the Middle Jurassic, representing a colony of tiny marine animals that lived approximately 166–168 million years ago.
The fossil is recorded as Bryozoa indet., meaning that it has been confidently identified as a bryozoan colony but has not been assigned to a more specific genus or species. This accurate identification reflects the type of preservation visible in the specimen while retaining its important geological and biological context.
Its recorded fossil group, Great Oolite provenance, Bathonian age and well-known Cotswold locality give this specimen excellent scientific, educational and collectable interest. It would make a distinctive addition to a collection of British fossils, Jurassic marine invertebrates, colonial organisms or natural-history specimens from the Cotswolds.
The photograph shows the exact fossil specimen you will receive. Full sizing and scale information can be seen in the accompanying photograph.
Great Oolite Group Geology
The Great Oolite Group is an important sequence of Middle Jurassic sedimentary rocks exposed across southern and central England. It includes limestone, marl, mudstone and sandstone deposited in a variety of shallow marine and coastal environments during the Bathonian.
At that time, the region now forming Gloucestershire lay much closer to the equator and was frequently covered by warm, shallow seawater. Carbonate mud, small rounded grains, broken shells and other skeletal material accumulated across tidal flats, lagoons, shoals and open areas of the seabed.
These sediments were gradually buried, compacted and cemented into the pale limestone for which the Cotswolds are famous. The resulting rocks preserve a diverse fossil assemblage that may include bryozoans, bivalves, brachiopods, gastropods, echinoids, corals, crinoids, ammonites and occasional vertebrate remains.
Bryozoan colonies could grow on shells, stones or other firm surfaces within these environments. After the colony died, its delicate calcareous skeleton became incorporated into the sediment. Continued burial and mineralisation preserved its structure within the developing limestone.
The specimen’s colour, matrix coverage, texture, incomplete areas and mineral staining are natural results of more than 160 million years of burial and geological change.
Bryozoan Colony Structure
Bryozoans are colonial aquatic animals composed of many tiny individuals called zooids. Each zooid lived within a small chamber known as a zooecium and contributed to the growth of the larger colony.
Although a bryozoan fossil can resemble coral, bryozoans belong to a separate group of animals with a distinctly different body structure. Each living zooid possessed a crown of fine, tentacle-like feeding structures called a lophophore. These were extended into the surrounding water to collect microscopic plankton and suspended organic particles.
The individual zooids reproduced by budding, creating genetically connected neighbours and gradually enlarging the colony. Depending on the species and environmental conditions, colonies could form thin encrusting sheets, branching structures, rounded masses, fans or irregular networks.
In fossil specimens, the original zooids may be represented by closely arranged pores, tubes, chambers or small openings across the colony surface. These repeated structures can create an intricate honeycomb-like or finely textured appearance when preserved clearly.
Because this example is identified as Bryozoa indet., its scientific importance lies in its colonial construction, Bathonian age and geological provenance rather than an unsupported species-level determination.
Middle Jurassic Marine Ecosystem
Bryozoans were important members of ancient seabed communities. Colonies commonly attached themselves to firm surfaces and filtered food from seawater passing over them. Their growth was influenced by current strength, sediment levels, available space and competition from other organisms.
A living colony may have provided shelter or attachment surfaces for other small marine animals. After death, its skeletal remains contributed calcium carbonate to the seabed and became part of the sedimentary material that later formed limestone.
The Great Oolite seas supported interconnected communities of suspension feeders, grazers, burrowing animals, predators and scavengers. Bryozoans shared these habitats with brachiopods, bivalves, sponges, echinoderms and other colonial organisms.
Their fossils provide evidence of ancient water conditions and seabed stability. Encrusting colonies indicate the presence of firm surfaces, while branching or more delicate forms can reflect calmer areas where fragile structures were less likely to be broken by strong currents.
Foss Cross Quarry Fossil from Gloucestershire
Foss Cross Quarry lies near Cirencester in the heart of the Cotswolds and exposes fossil-bearing rocks of the Middle Jurassic Great Oolite succession. Quarrying in this region has revealed extensive limestone beds deposited within the ancient Bathonian sea.
The locality is valued for the variety of marine fossils preserved within its limestone. These remains help reconstruct the changing environments, water depths and ecosystems that existed across Gloucestershire during the Middle Jurassic.
Fossils retaining accurate locality and geological information have greater scientific and collectable significance than specimens without recorded provenance. This example can be connected directly to the Great Oolite Group, the Bathonian Stage and a recognised British fossil locality.
It would suit a specialist collection of bryozoans, British Jurassic fossils, colonial marine organisms, Great Oolite specimens or educational material illustrating the diversity of prehistoric seabed life.
Actual Specimen with Certificate of Authenticity
This is a genuine fossil specimen and not a cast, replica or reproduction. It has been individually selected for its natural appearance, colonial structure and geological interest.
The photograph shows the actual Bryozoa indet. colony fossil you will receive. Full sizing is shown in the photograph.
A generic Certificate of Authenticity card is included with a lifetime guarantee of authenticity, providing lasting confidence that this is a genuine Bathonian fossil from the Great Oolite Group at Foss Cross Quarry, Cirencester, Gloucestershire, UK.
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