Description
Genuine Calycoceras subgentoni Ammonite Fossil – Cenomanian, Devon
This genuine fossil ammonite is identified as Calycoceras subgentoni, a collectable Upper Cretaceous ammonite from Devon, UK. Dating to the Cenomanian Stage of the Upper Cretaceous, this specimen represents marine life from approximately 100–94 million years ago, when warm Cretaceous seas covered large areas of Europe and supported a rich diversity of ammonites, bivalves, echinoids, fish, marine reptiles, and other prehistoric sea life.
This fossil is a carefully chosen specimen, with the photograph showing the actual fossil you will receive. Full sizing can be seen in the photo. It is supplied as a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card, making it an excellent addition to a fossil collection, educational display, natural history cabinet, or collection of British Cretaceous ammonites.
Fossil Type and Species
Ammonites were extinct marine cephalopods related to modern squid, cuttlefish, octopus, and nautilus. They lived inside coiled, chambered shells, with the animal occupying the final body chamber while the earlier chambers helped regulate buoyancy in the water column. Ammonites are among the most important fossils for dating Mesozoic marine rocks because they evolved rapidly, spread widely through ancient seas, and developed distinctive shell forms through time.
Calycoceras subgentoni belongs to the ammonite genus Calycoceras, a well-known Cretaceous ammonite group associated with the Cenomanian. Calycoceras is commonly placed within the family Acanthoceratidae, superfamily Acanthoceratoidea, and order Ammonitida. Acanthoceratid ammonites are especially recognised for their robust shell ornamentation, often including strong ribs, nodes, and tubercles. These bold shell features give many Calycoceras specimens a striking sculptural appearance and make them highly desirable to collectors.
Shell Morphology and Notable Features
Calycoceras ammonites typically display a strong coiled shell form with pronounced ribbing across the whorls. Many examples show raised tubercles or nodose features positioned along the ribs and shoulders of the shell, creating a rugged, architectural look that is characteristic of many Upper Cretaceous ammonites.
The shell is often moderately evolute, meaning the earlier whorls may remain partly visible rather than being completely enclosed by later growth. The ribs usually cross the flanks and can continue over the venter, adding definition to the overall form. These features may have helped strengthen the shell, influenced water flow around the ammonite, or played a role in species recognition.
As with all ammonites, the shell was originally divided into internal chambers connected by a siphuncle. The living animal occupied the outer body chamber, while the earlier chambers helped with buoyancy control. This allowed the ammonite to move through the Cretaceous sea as an active marine cephalopod.
Cenomanian Age and Geological Importance
The Cenomanian is the earliest stage of the Upper Cretaceous Period and marks an important time in ammonite evolution. Global sea levels were high, warm marine environments were widespread, and ammonites flourished in many parts of the world. The Cenomanian seas of western Europe produced many important ammonite faunas, including acanthoceratid groups such as Calycoceras.
Ammonites from the Cenomanian are particularly important in biostratigraphy. Because ammonite species evolved quickly and were widely distributed, their fossils are often used to identify and correlate rock layers. A named ammonite such as Calycoceras subgentoni carries stronger scientific and collecting interest than an unidentified example because it links the specimen to a specific ammonite group, geological stage, and ancient marine environment.
Devon, UK Cretaceous Marine Setting
This specimen comes from Devon, UK, a county with a rich and varied geological record. During the Cenomanian, parts of southern Britain were influenced by warm shallow seas connected to the wider Cretaceous marine basin of Europe. Lime-rich sediment, marine mud, shell debris, and other seabed deposits accumulated over time, preserving the remains of ammonites and other marine organisms.
The ancient sea would have supported a diverse ecosystem. Ammonites such as Calycoceras lived alongside bivalves, gastropods, echinoids, fish, and marine reptiles. After death, the shell could settle onto the sea floor and become buried by sediment. Over millions of years, mineral-rich waters and geological pressure transformed the remains into a fossil, preserving a direct connection to life in the Upper Cretaceous seas.
Collectable British Cretaceous Ammonite
This Calycoceras subgentoni ammonite fossil is a desirable specimen for collectors because it combines a named species, British locality, Upper Cretaceous age, and classic Cenomanian ammonite character. Its robust acanthoceratid form makes it an attractive display fossil, while its geological information gives it strong educational and scientific value.
Named fossils with clear locality and age details are especially popular with collectors because they provide more context than unidentified specimens. This ammonite is ideal for display in a fossil cabinet, addition to a labelled ammonite collection, use in an educational geology setting, or as a natural history specimen for anyone interested in prehistoric marine life.
Authenticity and Presentation
This fossil is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. The specimen has been carefully selected, and the photograph shows the actual fossil you will receive. Full sizing can be seen in the photo.
As a genuine Calycoceras subgentoni ammonite from the Cenomanian Upper Cretaceous of Devon, UK, this fossil offers an attractive and scientifically interesting example of British Cretaceous marine life, with strong appeal for collectors of ammonites, fossils, and natural history specimens.
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