Description
Genuine Osperlioceras suessi Ammonite Fossil
This carefully chosen specimen is a genuine Osperlioceras suessi ammonite fossil from Toarcian deposits at Saint-Paul-des-Fonts in Aveyron, Occitanie, southern France. It represents an extinct marine cephalopod that inhabited the seas of western Europe during the latter part of the Early Jurassic.
With its naturally coiled shell, recognised species identification and recorded French locality, this specimen offers an attractive combination of palaeontological interest and natural display appeal. Ammonites are among the most distinctive fossils of the Mesozoic Era and are particularly valued for their importance in identifying and correlating marine rock sequences.
The listing photograph shows the actual fossil you will receive, rather than a stock photograph or representative example. Its individual form, preservation, colour, matrix and visible surface details can therefore be examined before purchase. Full sizing is shown in the accompanying photograph.
Fossil Classification and Geological Details
Scientific name: Osperlioceras suessi
Historical combination: Pseudolioceras suessi
Fossil type: Ammonite
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Hildoceratoidea
Family: Hildoceratidae
Genus: Osperlioceras
Geological period: Jurassic
Epoch: Early Jurassic
Stage: Toarcian
Locality: Saint-Paul-des-Fonts, Aveyron, Occitanie, France
The genus is also widely written Osperleioceras in palaeontological literature. O. suessi was named by the French palaeontologist Émile Monestier in 1921 and was historically placed in the genus Pseudolioceras. The broader classification of this ammonite group has been revised by different researchers, but it is generally associated with the hildoceratid ammonites of the Toarcian.
Characteristic Osperlioceras Shell Morphology
The shell grew in a flat spiral known as planispiral coiling. Each new whorl increased in size as the ammonite matured, producing the familiar circular form. The central exposed region is called the umbilicus, the sides of the shell are known as the flanks, and the outermost edge is called the venter.
Osperlioceras ammonites are generally recognised by relatively involute and compressed shells. In involute coiling, each succeeding whorl overlaps much of the previous one, leaving a comparatively restricted umbilical opening. The whorl section commonly narrows from its broadest region near the umbilicus towards a slim ventral margin.
A prominent keel may extend around the venter, forming a raised ridge along the shell’s outer edge. This feature contributed to the ammonite’s streamlined profile and is an important characteristic of many hildoceratid ammonites. Subtle ventrolateral ridges may also occur alongside the principal keel.
The shell ornament typically includes falcoid or sickle-shaped ribs. These begin upon the flanks and curve forwards more strongly as they approach the venter. Rib strength, density and curvature may vary through growth, meaning that the inner juvenile whorls can differ noticeably from the mature outer section.
Depending on preservation, this specimen may display ribbing, growth lines, whorl boundaries, portions of the keel or areas of original shell material. Attached matrix, mineral deposits, incomplete margins and natural surface wear are authentic features of fossilisation rather than manufactured imperfections.
Chambered Shell and Ammonite Anatomy
The living ammonite occupied the final and largest section of the shell, called the body chamber. The older inner portion was divided into a succession of sealed chambers by curved internal walls known as septa.
A slender organic tube called the siphuncle connected the chambers. By regulating the quantities of liquid and gas within them, the ammonite could control its buoyancy and maintain an effective position within the water column.
Where the septa met the exterior shell wall, they produced complex lines called sutures. In hildoceratid ammonites these patterns can be highly intricate, with branching lobes and saddles. Sutures may become visible where the original outer shell layer has weathered away or has been carefully exposed during preparation.
The soft-bodied animal was related to other cephalopods and probably possessed well-developed eyes, grasping appendages and a muscular funnel used for jet-propelled movement. Its chambered shell combined physical protection with a highly specialised buoyancy system.
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 extended from approximately 184 to 174 million years ago.
This interval witnessed substantial environmental and evolutionary change within the world’s oceans. Variations in climate, sea level, ocean circulation and oxygen availability influenced marine ecosystems, while ammonites diversified into numerous distinctive lineages.
Ammonites are especially important as index fossils because they evolved rapidly and were distributed across extensive marine regions. Different species appeared and disappeared through relatively short intervals, allowing palaeontologists to divide Toarcian rocks into detailed biozones, subzones and individual fossil horizons.
A correctly identified specimen such as Osperlioceras suessi therefore preserves more than the remains of a prehistoric animal. It also represents part of the ammonite succession used to interpret and correlate Lower Jurassic marine strata.
Jurassic Marine Environment of Aveyron
During the Toarcian, the area now forming Aveyron lay beneath a marine basin connected to the western Tethys Ocean. The limestone plateaux, valleys and rocky landscapes of modern Occitanie developed from sediments deposited across these ancient marine environments.
Fine carbonate mud, clay and organic debris accumulated upon the seabed. The sea supported diverse communities 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 temporarily or descend directly to the seabed. Burial beneath soft sediment helped protect it from scavengers, currents and complete dissolution. Additional layers accumulated above the shell, gradually compacting and hardening into sedimentary rock.
Mineral-rich groundwater could enter the shell chambers, replace the original shell material or create a solid internal mould. Geological uplift and erosion later exposed the fossil-bearing Toarcian strata around Aveyron, allowing specimens such as this one to be recovered.
Saint-Paul-des-Fonts Fossil Locality
Saint-Paul-des-Fonts is situated within the Aveyron department of southern France, an area noted for its extensive Jurassic sedimentary rocks and varied ammonite faunas. Fossils with recorded locality information are particularly desirable because their origin provides geological context and connects the specimen to a recognised fossil-bearing region.
The Toarcian rocks of Aveyron preserve an important record of marine cephalopod evolution. Ammonites from these deposits display a wide range of shell shapes, coiling styles and ornamentation, reflecting both evolutionary diversification and changing environmental conditions within the ancient basin.
Actual Specimen 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, completeness and surface preservation are authentic results of burial, fossilisation and natural weathering.
The listing photograph shows the exact Osperlioceras suessi ammonite fossil that will be supplied. Full sizing is provided in the photograph so that its dimensions can be assessed before purchase.
The fossil includes a generic Certificate of Authenticity card carrying a lifetime guarantee of authenticity. It is an excellent addition to a French fossil collection, Jurassic ammonite display, geological teaching collection or natural-history cabinet.
Reviews
There are no reviews yet.