Description
Genuine Acanthoceras rhotomagense Ammonite Fossil – Cenomanian, France
This genuine fossil ammonite is identified as Acanthoceras rhotomagense, a classic Upper Cretaceous ammonite from France. Dating to the Cenomanian Stage of the Upper Cretaceous, this specimen represents marine life from approximately 100–94 million years ago, during a time when warm seas covered large areas of Europe and supported a rich diversity of ammonites, bivalves, echinoids, marine reptiles, fish, and other ancient 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 suitable for fossil collectors, educational displays, natural history collections, and anyone interested in 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. Ammonites are among the most important fossils for dating Mesozoic rocks because they evolved rapidly and were widely distributed across ancient seas.
Acanthoceras rhotomagense is one of the best-known Cenomanian ammonites and is strongly associated with Upper Cretaceous marine deposits of Europe. The species was originally described by Alexandre Brongniart in the early 19th century and has long been recognised as an important ammonite for Cretaceous stratigraphy.
This species belongs to the family Acanthoceratidae, within the superfamily Acanthoceratoidea and order Ammonitida. Members of Acanthoceras are especially recognisable for their robust, ornamented shells, often showing strong ribbing and tubercles. These features give the fossil a bold, sculptural appearance and make it highly attractive to collectors of ammonites and Cretaceous marine fossils.
Shell Morphology and Notable Features
Acanthoceras ammonites typically have a strong, well-ornamented shell with prominent ribs crossing the whorls. Many specimens display tubercles, or raised nodes, along the ribs and shoulders of the shell. These features may have strengthened the shell, influenced hydrodynamics, or played a role in species recognition.
The shell form of Acanthoceras rhotomagense is often moderately evolute, meaning the earlier whorls may remain partly visible rather than being completely covered by later growth. The combination of strong ribs, nodose ornamentation, and Cretaceous age makes this species instantly appealing as a display fossil. Even when preserved with natural wear or matrix, the distinctive Acanthoceras form remains an excellent example of Upper Cretaceous ammonite evolution.
Cenomanian Age and Geological Importance
The Cenomanian is the earliest stage of the Upper Cretaceous Period. It was a time of high global sea levels, with warm shallow seas spreading across many continental areas. In France, Cenomanian marine deposits are well known for producing ammonites and other fossils that help reveal the biodiversity of these ancient seas.
Acanthoceras rhotomagense is especially important because it is associated with the Rhotomagense Zone, a well-recognised Cenomanian ammonite biozone. Ammonite biozones are used by geologists to divide and correlate rock layers with precision, as ammonites changed rapidly through time. This gives the species strong scientific value as well as visual and collecting appeal.
Depositional Environment
During the Cenomanian, much of what is now France was influenced by shallow marine environments connected to the wider Cretaceous seas of western Europe. These seas supported abundant plankton, fish, marine reptiles, and a wide range of invertebrates. Ammonites such as Acanthoceras would have lived as active marine cephalopods, moving through the water column and forming part of a complex food web.
After death, the ammonite shell settled onto the sea floor, where it could become buried by sediment. Over millions of years, mineral-rich waters and geological pressure transformed the shell and surrounding sediment into fossil-bearing rock, preserving this ancient marine animal as a tangible piece of Cretaceous history.
Collectable Cretaceous Ammonite
This Acanthoceras rhotomagense ammonite fossil is a desirable specimen for collectors because it combines a named species, Upper Cretaceous age, French provenance, and strong scientific interest. Its robust shell style and association with the Cenomanian make it an excellent choice for fossil cabinets, educational collections, geology displays, and natural history enthusiasts.
Named ammonites with clear geological information are particularly valued because they provide more than visual appeal. They connect the specimen to a specific time period, fossil group, and ancient marine environment, giving the fossil stronger collecting and educational value than an unidentified ammonite.
Authenticity and Presentation
This fossil is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. The photograph shows the actual fossil you will receive, and full sizing can be seen in the photo. As a genuine Acanthoceras rhotomagense ammonite from the Cenomanian of France, this specimen offers an attractive and scientifically interesting example of Upper Cretaceous marine life.
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