Olcostephanus astierianus Ammonite Fossil France with COA

Description

Genuine Olcostephanus astierianus Ammonite Fossil

This genuine ammonite fossil is identified as Olcostephanus astierianus and comes from the Drôme region of France. It dates to the Barremian Stage of the Lower Cretaceous and is a carefully chosen European specimen with valuable species, geological age, and locality information. The photographs show the actual fossil offered for sale, so the ammonite pictured is the exact specimen you will receive.

Barremian Lower Cretaceous Age

The Barremian is a stage of the Early Cretaceous Period, spanning approximately 129 to 125 million years ago. During this interval, warm seas covered extensive areas of southern Europe and the Tethyan realm. Marine communities included ammonites, belemnites, bivalves, gastropods, fish, and other organisms adapted to open-water and sea-floor environments.

After death, an ammonite shell could settle onto the seabed and become buried by fine marine sediment. Compaction, mineralisation, and later geological uplift preserved the shell or internal mould as a fossil. The documented Barremian age gives this specimen a precise position within the Lower Cretaceous succession.

Olcostephanus astierianus

Olcostephanus was an extinct marine cephalopod with a coiled shell divided internally into chambers. The animal lived in the final body chamber, while earlier sealed chambers contributed to buoyancy control. Ammonites were relatives of modern squid, cuttlefish, and nautiluses, although they formed their own diverse and now extinct group.

Olcostephanus is known for robust shell forms and strong ornament. Specimens may show prominent ribs, bundles of secondary ribs, umbilical tubercles, and a rounded outer whorl. These structural features help palaeontologists compare species and interpret growth. Examine the supplied photographs for the whorl shape, rib pattern, tubercles, umbilical area, matrix, and preserved surface detail visible on this individual Olcostephanus astierianus.

Scientific and Stratigraphic Interest

Ammonites evolved relatively rapidly and were widely distributed through Cretaceous seas. Their changing shell forms make them valuable index fossils, enabling geologists to correlate marine rocks and establish relative ages. Olcostephanus is characteristic of particular Lower Cretaceous successions and contributes to understanding Barremian marine faunas and palaeogeography.

An ammonite shell grew by adding progressively larger chambers around the outer whorl. Internal septa met the shell wall along complex suture lines, reinforcing the chambered structure. External ribs and tubercles also added strength and may have influenced hydrodynamics. The combination of shell shape and ornament gives each preserved specimen its distinctive fossil character.

Drôme Geological Provenance

Drôme lies in southeastern France, within a region celebrated for extensive Lower Cretaceous marine sedimentary rocks. These strata formed along the ancient margins of the Tethys Ocean and are internationally important for ammonite biostratigraphy. Fossils from this area document changing seas, sedimentation, and marine life during the Early Cretaceous.

A specimen with documented Drôme provenance carries more collecting and educational context than an unlocalised fossil. It can complement a collection arranged by European country, French region, geological stage, ammonite genus, or ancient marine environment.

Natural Fossil Character

Natural colour, mineral texture, small breaks, areas of wear, and differences in preservation reflect the fossil’s long geological history. These are expected features of an authentic specimen rather than manufacturing defects. Every ammonite preserves a different balance of shell material, mineral replacement, internal mould, and surrounding rock, giving each piece unique display qualities.

The multiple photographs show this exact Olcostephanus astierianus from useful angles. They allow close inspection of its condition, ornament, outline, matrix, and proportions. 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 specimen.

Certificate of Authenticity

This genuine fossil includes a generic Certificate of Authenticity card with a lifetime guarantee. Its Barremian age, classic French provenance, characteristic robust ammonite form, and authentic preservation make it a distinctive 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, palaeontology, or genuine natural history specimens.