Description
Genuine Cadomites Ammonite Fossil
This carefully chosen specimen is a genuine Cadomites sp. ammonite fossil from Caen in Calvados, Normandy, France. It dates from the Bajocian Stage of the Middle Jurassic and represents an extinct marine cephalopod that inhabited the warm seas of western Europe approximately 168–171 million years ago.
The fossil has been identified confidently to the genus Cadomites, while the species remains open and is therefore recorded accurately as Cadomites sp. Its recognised Middle Jurassic age and documented Normandy locality give the specimen strong geological, educational and collectable interest.
This fossil would make an excellent addition to a collection of ammonites, French fossils, Jurassic marine life, extinct cephalopods or natural-history specimens with recorded provenance. The photograph shows the actual fossil specimen you will receive. Full sizing and scale information can be seen in the accompanying photograph.
Bajocian Middle Jurassic Geology
The Bajocian is one of the four stages forming the Middle Jurassic Period. It takes its name from the historic Normandy town of Bayeux, making fossils from Calvados especially significant in the history of Jurassic geology and palaeontology.
During the Bajocian, the area now forming northern France was covered by warm, shallow to moderately deep marine waters. These seas were connected to a much wider system of marine basins extending across western Europe. Fine carbonate mud, mineral grains, broken shells and the remains of marine organisms accumulated gradually across the seabed.
Through burial, compaction and natural cementation, these sediments eventually became limestone, marl and other fossil-bearing sedimentary rocks. The Bajocian seas supported a diverse ecosystem containing ammonites, nautiloids, belemnites, brachiopods, bivalves, gastropods, echinoids, crustaceans and numerous other marine invertebrates.
When the ammonite died, its shell settled onto the seabed and could become buried beneath layers of sediment. The original shell material might later be mineralised, replaced or dissolved, leaving an impression, mould or stone-filled representation of the shell’s chambered interior. Colour variations, matrix deposits, mineral staining, weathered areas and incomplete sections are natural products of this long fossilisation process.
Cadomites Shell Morphology
Cadomites is a distinctive genus of Middle Jurassic ammonites placed within the family Stephanoceratidae and the superfamily Stephanoceratoidea of the order Ammonitida. Members of this group are particularly recognised for their robust shell form and strongly developed ornamentation.
The shell is planispirally coiled, with each successive whorl developing around a central umbilical region within the same plane. Cadomites commonly displays a moderately evolute form, allowing part of the earlier whorls to remain visible within the open umbilicus.
The ornamentation typically consists of strong primary ribs beginning near the umbilical margin. These ribs may develop raised nodes or tubercles on the flanks before dividing into two or more secondary ribs. The secondary ribs then continue across the rounded outer margin of the shell. This combination of pronounced ribbing, branching ornament and tuberculation gives Cadomites ammonites their characteristic sculptured appearance.
Shell proportions and ornamentation could change as the ammonite matured. Earlier whorls may show finer and more closely spaced ribs, while later growth can become broader, more robust and more strongly ornamented. Depending on its preservation, this specimen may display portions of the inner and outer whorls, radial ribs, branching rib patterns, tubercles, the umbilical region, internal chambers or surrounding Jurassic matrix.
Extinct Jurassic Marine Cephalopod
Ammonites were marine molluscs related to modern squid, cuttlefish, octopuses and nautiluses. Unlike most living cephalopods, they possessed a hard external shell divided internally into a succession of chambers.
The living animal occupied the final and largest section of the shell, known as the body chamber. The earlier chambers formed the phragmocone, which contributed to buoyancy control. A narrow connecting structure called the siphuncle passed through these chambers and helped regulate the balance of liquid and gas inside them.
As the ammonite grew, it added progressively larger chambers around the outside of its shell. Internal partitions known as septa separated the chambers. Where the septa met the shell wall, they formed intricate patterns called suture lines.
Palaeontologists use shell shape, whorl proportions, ribbing, tubercle arrangement, umbilical width and suture patterns when identifying and classifying ammonites. Because ammonites evolved rapidly and were distributed across extensive marine areas, their fossils are also valuable for comparing and dating Jurassic rock sequences.
Caen Fossil from Calvados, Normandy
Caen and the surrounding Calvados region are internationally recognised for their Jurassic limestone, historic quarries and important fossil discoveries. The area preserves a detailed record of the marine environments that covered Normandy during the Middle Jurassic.
Ammonites from this region provide evidence of changing sea levels, sedimentary conditions, marine biodiversity and cephalopod evolution. The close historical connection between Normandy and the definition of the Bajocian Stage gives fossils from Calvados additional geological importance.
A specimen retaining its genus identification, geological stage and collection locality has greater scientific and collectable significance than an ammonite without recorded provenance. This Cadomites sp. would make a distinctive addition to a specialist ammonite collection, geological study cabinet, educational display or collection of French Jurassic fossils.
Actual Specimen with Certificate of Authenticity
This is a genuine fossil specimen and not a cast, replica or reproduction. It has been individually selected for its natural form, geological character and collectable appeal.
The photograph shows the exact Cadomites sp. ammonite fossil you will receive. Full sizing is shown in the photograph.
A generic Certificate of Authenticity card is included with a lifetime guarantee of authenticity, providing lasting confidence that this is a genuine Bajocian ammonite fossil from the Middle Jurassic of Caen, Normandy, France.
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