Description
Genuine Gruneria gruneri Ammonite Fossil from France
This genuine Gruneria gruneri ammonite fossil originates from Truc de Balduc in Occitanie, southern France. Dating from the Lower Toarcian Stage of the Lower Jurassic Period, it represents an extinct marine cephalopod that inhabited the ancient European seas approximately 180 million years ago.
The fossil has been carefully chosen for its natural character, scientific interest and individual preservation. The listing photographs show the actual specimen you will receive, rather than a stock image or representative example. Its visible shell form, ornamentation, mineralisation, natural colour and any retained matrix can therefore be examined before purchase.
Please refer to the photographs for full sizing, scale and a detailed assessment of the specimen’s condition.
Lower Toarcian Geological Age
The Toarcian is the final stage of the Lower Jurassic Epoch, following the Pliensbachian and preceding the Aalenian. The Lower Toarcian records an important chapter in Jurassic marine history, including major environmental changes that influenced ocean chemistry, sedimentation and the distribution of marine organisms.
Ammonites are especially useful to palaeontologists because their shell forms changed rapidly through evolutionary time. Many species occupied broad marine regions but existed for comparatively short geological intervals, making them valuable index fossils for dating and correlating sedimentary rocks.
A locality-recorded specimen such as this Gruneria gruneri from Truc de Balduc retains meaningful geological context. Lower Toarcian deposits at this locality include bituminous marine sediments interpreted as representing the deepest-water phase of a broader sedimentary cycle, with recognised faunal and environmental links between southern France and other European basins.
Gruneria gruneri Shell Characteristics
Gruneria gruneri possessed a planispirally coiled shell divided internally into a succession of chambers. The living animal occupied the final and largest body chamber, while the older sealed chambers formed the phragmocone. These internal chambers were connected by a narrow tube called the siphuncle, which allowed the ammonite to regulate the balance of liquid and gas within its shell and control its buoyancy.
The shell developed as a series of overlapping whorls around a central umbilicus. Depending on the animal’s growth stage and the degree of preservation, some of the earlier whorls may remain visible within this central region.
Ornamentation consists of ribs extending across the flanks of the shell. Their strength, spacing and curvature may vary as the ammonite grows, meaning the inner whorls can display a different appearance from the later adult shell. The outer margin may also retain a defined ventral structure or keel, although the visibility of these features depends upon fossilisation, preparation and natural weathering.
Ribbing provided structural reinforcement to the original shell and now supplies important morphological information for fossil identification. Surface wear, incomplete areas, fine fractures, mineral deposits and attached rock are all natural characteristics of authentic fossils and form part of this specimen’s geological history.
Scientific Classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Hildoceratoidea
Family: Hildoceratidae
Genus: Gruneria
Species: Gruneria gruneri
Gruneria gruneri is classified within the ammonite family Hildoceratidae, a diverse group of Jurassic ammonoids distinguished through features such as shell proportions, coiling, rib development and ventral morphology.
Ammonites were marine molluscs related to living cephalopods such as squid, cuttlefish, octopuses and nautiluses. They flourished throughout much of the Mesozoic Era, evolving into an extraordinary variety of shell forms before becoming extinct at the end of the Cretaceous Period.
Jurassic Marine Environment of Truc de Balduc
During the Lower Toarcian, the region now forming southern France was covered by marine waters connected with the western Tethyan realm. Fine mud, organic matter, carbonate material and the remains of marine organisms accumulated across the seabed.
The Lower Toarcian succession at Truc de Balduc is particularly associated with dark, organic-rich bituminous sediments deposited under comparatively deep marine conditions. Some limestone horizons within this succession can be correlated over considerable distances, demonstrating the broader connection between Toarcian marine environments across Europe.
After the ammonite died, its shell settled onto the sea floor. Burial beneath fine sediment protected at least part of it from currents, scavenging and complete dissolution. Continued sediment accumulation increased pressure around the shell, gradually compacting the deposit and transforming it into sedimentary rock.
Mineral-bearing groundwater later passed through the buried layers, filling empty spaces and preserving or replacing portions of the original shell. Any visible matrix, mineral veins, colour variations or areas of shell loss are therefore genuine products of fossilisation and subsequent geological exposure.
Actual Fossil with Certificate of Authenticity
This is a 100% genuine fossil specimen, not a replica, cast or modern reproduction. It is supplied with a generic Certificate of Authenticity card carrying a lifetime guarantee, providing lasting reassurance regarding its genuine fossil status.
The photographs show the exact Gruneria gruneri ammonite fossil that will be supplied. The specimen received will therefore have the same preservation, natural colour, shell detail, matrix and individual surface features visible in the listing images.
This Lower Toarcian ammonite is suitable for Jurassic fossil collections, ammonite displays, geological teaching collections, natural-history cabinets and gifts for fossil enthusiasts. Its identified species, recorded Truc de Balduc locality and French Lower Jurassic origin make it a distinctive addition to a carefully organised palaeontological collection.
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