Description
Genuine Sphaerocoeloceras brochiiiforme Ammonite Fossil
This carefully selected specimen is a genuine Sphaerocoeloceras brochiiiforme ammonite fossil from Toarcian deposits in Aveyron, Occitanie, southern France. It represents an extinct marine cephalopod that inhabited the warm seas covering this part of Europe during the latter portion of the Early Jurassic.
Ammonites are highly collectable fossils recognised by their distinctive spirally coiled shells. They were once abundant throughout the world’s oceans and are related to living cephalopods such as squid, cuttlefish and nautiluses. Their widespread distribution, rapid evolution and varied shell forms also make them especially important to palaeontologists studying Jurassic rocks.
The photograph shows the actual specimen you will receive rather than a stock photograph or representative example. Its individual shell form, preservation, matrix, colour and natural surface characteristics can therefore be examined before purchase. Full sizing is shown in the accompanying photograph.
Fossil Classification and Geological Details
Scientific name: Sphaerocoeloceras brochiiiforme
Fossil type: Ammonite
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Eoderoceratoidea
Family: Dactylioceratidae
Genus: Sphaerocoeloceras
Geological period: Jurassic
Epoch: Early Jurassic
Stage: Toarcian
Locality: Aveyron, Occitanie, France
Sphaerocoeloceras is recognised as a distinct ammonite genus within formal palaeontological classification. Its compact shell proportions and strong ornamentation distinguish it from many of the more compressed and finely ribbed ammonites found within Toarcian marine deposits.
Distinctive Ammonite Morphology
The shell of Sphaerocoeloceras grew in a flat spiral, with each successive whorl increasing in size as the animal matured. The central exposed area is known as the umbilicus, the sides of the shell are called the flanks, and the outermost edge is known as the venter.
Ammonites of this genus are generally associated with compact, strongly inflated whorls and a comparatively robust shell profile. The coiling may leave a clearly visible umbilical region, while the rounded flanks carry pronounced radial ornamentation. Strong ribs commonly extend outwards from the umbilical margin and cross towards the ventral region.
Depending on growth stage and preservation, some ribs may appear thicker, raised or slightly swollen upon the flanks. The ornament may also change as the shell increases in diameter, providing palaeontologists with useful evidence when comparing related species and different stages of ammonite development.
The robust shell form gives Sphaerocoeloceras a noticeably different appearance from thin, sharply keeled Toarcian ammonites. Its rounded proportions and substantial ribbing create an appealing natural texture, particularly where the shell surface has been cleanly exposed from the surrounding matrix.
Any areas of weathering, incomplete shell, mineral infill or attached rock are genuine characteristics resulting from fossilisation and do not detract from the specimen’s authenticity.
Chambered Shell and Ammonite Life
During life, the ammonite occupied the final and largest section of its shell, called the body chamber. The older inner portion was divided into numerous chambers by curved internal walls known as septa.
A slender tube called the siphuncle passed through these chambers. By regulating the balance of liquid and gas within the chambered shell, the ammonite could control its buoyancy and maintain its position in the water column. Movement was probably achieved partly through jet propulsion, with water expelled through a muscular funnel.
The animal’s soft body would have included a head, eyes and a crown of grasping appendages used to capture food. Its rigid external shell offered protection while also functioning as a highly specialised buoyancy system.
Where the septa joined the exterior wall, they formed complex patterns called suture lines. These may become visible when the outer shell layer is removed by natural weathering or fossil preparation. Suture patterns are important diagnostic features in ammonite classification and became increasingly elaborate through ammonite evolutionary history.
Toarcian Stage of the Early Jurassic
The Toarcian is the final stage of the Early Jurassic Epoch, following the Pliensbachian and preceding the Aalenian Stage of the Middle Jurassic. It represents an interval approximately 184 to 174 million years ago.
This was a period of significant environmental and biological change. Marine ecosystems were affected by variations in climate, ocean chemistry, oxygen levels and sea level. Despite episodes of environmental disruption, ammonites remained diverse and evolved rapidly into numerous recognisable lineages.
Because ammonite species changed through time and were distributed over extensive marine areas, they are among the most useful index fossils found in Jurassic rocks. Particular ammonite assemblages allow geologists to divide sedimentary successions into detailed biozones and compare strata exposed in widely separated regions.
A correctly recorded Toarcian ammonite therefore has scientific value beyond its decorative spiral form. It preserves evidence of both an extinct animal and the geological interval in which it lived.
Jurassic Marine Environment of Aveyron
During the Toarcian, the region now forming Aveyron lay within a marine basin connected to the western Tethys Ocean. The limestone plateaux, valleys and rocky uplands visible across modern southern France developed from sediments that accumulated in these ancient marine environments.
Fine carbonate mud, clay and organic material settled upon the seabed. These sediments preserved a varied ecosystem containing ammonites, belemnites, bivalves, brachiopods, gastropods, crinoids, fish and other marine organisms. Larger predators, including marine reptiles, occupied the surrounding waters.
After death, an ammonite shell could drift for a short period or sink directly to the seabed. If it was buried before being destroyed by scavengers, currents or chemical dissolution, the shell could enter the fossil record.
Additional layers of sediment accumulated above it, gradually compacting and hardening into rock. Mineral-rich groundwater could fill the shell’s chambers, replace original shell material or produce a solid internal mould preserving the shape of the animal’s chambered shell. Later geological uplift and erosion exposed the fossil-bearing strata from which specimens such as this could be recovered.
Actual Fossil and Certificate of Authenticity
This is a genuine fossil specimen and not a replica, cast or modern reproduction. It has been individually selected for its natural character, geological interest and collectable appearance. Variations in colour, matrix, mineralisation, texture, completeness and surface preservation are authentic results of burial, fossilisation and natural weathering.
The listing photograph shows the exact Sphaerocoeloceras brochiiiforme ammonite fossil that will be supplied. Full sizing is provided in the photograph so that the specimen’s dimensions can be assessed before purchase.
The specimen includes a generic Certificate of Authenticity card carrying a lifetime guarantee of authenticity. It is an excellent addition to an ammonite collection, French Jurassic display, geological teaching collection or natural-history cabinet and would make a distinctive gift for a fossil collector, palaeontology enthusiast or admirer of prehistoric marine life.
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