Description
Genuine Holcodiscus caillaudianus Ammonite Fossil
This genuine ammonite fossil is identified as Holcodiscus caillaudianus and comes from Mont de Lure in Alpes-de-Haute-Provence, France. It dates to the Barremian stage of the Lower Cretaceous. The photographs show the actual carefully selected fossil offered for sale, so the ammonite pictured is the exact specimen you will receive.
Barremian Lower Cretaceous Age
The Barremian is an Early Cretaceous stage dating to approximately 129 to 125 million years ago. During this interval, southeastern France lay within the marine realm of the ancient Tethys Ocean. Warm waters supported ammonites, belemnites, bivalves, gastropods, echinoids, corals, and many other organisms.
After death, an ammonite shell could settle onto the seabed and become buried by marine sediment. Compaction, mineral replacement, and lithification preserved the shell or its internal mould. Later Alpine uplift, folding, erosion, and weathering raised these deposits above sea level and exposed fossil-bearing rocks in Provence.
Holcodiscus caillaudianus
Holcodiscus was an extinct marine cephalopod with a coiled shell divided internally into chambers. The living animal occupied the final body chamber, while earlier sealed chambers helped regulate buoyancy. Ammonites were relatives of modern squid, cuttlefish, and nautiluses, although they formed their own highly diverse and now extinct group.
Fossil specialists distinguish ammonites by comparing shell form, whorl proportions, umbilical width, ribs, constrictions, tubercles, and the shape of the outer edge. Holcodiscus caillaudianus may display robust coiling and strong ornament that changes through growth. Examine the photographs for the whorls, rib pattern, umbilical area, outer margin, natural matrix, and individual preservation visible on this specimen.
Ammonites and Geological Dating
Ammonites evolved rapidly and were widely distributed through Mesozoic seas. Their changing shell forms make them valuable index fossils, allowing geologists to compare marine rock sequences and determine relative ages. Barremian ammonite assemblages from southeastern France are particularly important in the correlation of Lower Cretaceous strata around the former Tethyan region.
A specimen identified to species and linked to a precise mountain locality carries richer geological context than one described only as broadly Cretaceous. It can be compared with related ammonites to illustrate evolutionary succession, geographical distribution, and diversity within Early Cretaceous marine communities.
Tethyan Marine Environment
During the Barremian, carbonate mud, marl, and fine sediment accumulated in marine basins and shelf settings connected to the Tethys Ocean. Water depth, currents, oxygenation, biological productivity, and sediment supply influenced both the living community and the conditions under which shells were preserved.
The chambered shell illustrates adaptation in a free-swimming marine cephalopod. Its construction combined strength with buoyancy control, while ornament and shell form may have affected reinforcement and movement through the water. Each fossil preserves a unique balance of original shell, mineral replacement, internal mould, matrix, and later geological alteration.
Mont de Lure Provenance
Mont de Lure rises in Alpes-de-Haute-Provence within a region renowned for fossiliferous Mesozoic marine rocks. These strata were deposited in or near the Tethyan realm before later deformation and uplift associated with Alpine mountain building. A documented Mont de Lure provenance adds geographical, scientific, and educational value to this ammonite.
This specimen can complement a collection arranged by French locality, geological stage, ammonite genus, fossil group, or ancient marine environment. Its Provençal origin also illustrates the transformation of former seabed deposits into the dramatic mountain landscapes of southeastern France.
Natural Fossil Character
Natural colour, mineral texture, small breaks, areas of wear, and variations in preservation are expected features of an authentic fossil rather than manufacturing defects. They reflect burial, mineralisation, rock formation, tectonic uplift, and weathering over immense geological time. No two ammonites preserve exactly the same combination of detail.
The multiple photographs show this exact Holcodiscus caillaudianus specimen from useful angles. They allow close inspection of its condition, coiling, ribbing, matrix, proportions, and display qualities. Full sizing is shown in the photographs, which provide the clearest scale information for this individual fossil. The images are not stock photographs and do not represent a similar item.
Certificate of Authenticity
This genuine fossil includes a generic Certificate of Authenticity card with a lifetime guarantee. Its Barremian age, detailed ammonite identity, and Mont de Lure provenance make it an appealing addition to a fossil cabinet, study collection, office display, or educational setting. It is also a thoughtful gift for anyone interested in French fossils, Lower Cretaceous geology, ammonite evolution, Alpine geology, or authentic natural history specimens.
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