Rare Acanthoceras rhotomagense Fossil Ammonite Middle Cenomanian Cretaceous Sussex UK 9 Inch Genuine Certified Collector Specimen

Description

Rare Acanthoceras rhotomagense Fossil Ammonite from Sussex, United Kingdom

This outstanding Acanthoceras rhotomagense fossil ammonite is an exceptional and scientifically important specimen from the Middle Cenomanian stage of the Late Cretaceous, discovered in the fossil-rich chalk deposits of Sussex, UK. Measuring approximately 9 inches across, it is a fine representation of this iconic species, offering a remarkable combination of size, preservation, and geological significance. The photographs provided show the actual specimen you will receive, ensuring complete authenticity.

Geological Context and Formation

The Middle Cenomanian (around 100.5–93.9 million years ago) represents an interval during the early part of the Late Cretaceous when warm, shallow seas covered much of present-day southern England. In Sussex, thick chalk and marl sequences were deposited in calm, open-marine conditions that provided an ideal environment for the preservation of marine life. Within these sediments, ammonites such as Acanthoceras rhotomagense flourished, leaving behind beautifully preserved shells that now serve as key reference points in geological dating and correlation.

Scientific Classification

• Species: Acanthoceras rhotomagense
• Family: Acanthoceratidae
• Superfamily: Acanthoceratoidea
• Order: Ammonitida
• Geological Stage: Middle Cenomanian, Late Cretaceous

Acanthoceras rhotomagense is a zonal index fossil, meaning it has a very specific age range and is used by geologists to precisely date rock layers. Its distribution across Europe and beyond makes it an invaluable species for paleontological and stratigraphic research.

Morphological Characteristics

This specimen displays all the key diagnostic features of Acanthoceras rhotomagense, including:

• Broad, robust whorls with a moderately involute coiling pattern, giving the shell a strong and solid appearance.
• Sharp, regular ribbing that crosses the shell with precision, highlighting the radial symmetry.
• Pronounced tubercles and spines along the ventrolateral margins, characteristic of the genus, providing both hydrodynamic stability in life and stunning visual detail in fossil form.
• Well-preserved suture lines, revealing the complex internal chambering used by the animal to regulate buoyancy.

These physical traits make it both a scientifically important specimen and a highly attractive display piece.

Paleoecology and Ancient Seas

As a member of the ammonite subclass, Acanthoceras rhotomagense was a free-swimming cephalopod closely related to modern squid and cuttlefish. It likely inhabited the mid to upper levels of the Cretaceous sea, hunting small fish, crustaceans, and plankton. Its sturdy shell design, combined with its hydrodynamic ribbing and tuberculation, would have helped it move efficiently through the water while offering some protection from predators.

When the animal died, its shell sank to the sea floor and became quickly buried in fine carbonate sediment, preventing scavenging and preserving fine details. Over millions of years, the original shell material was replaced or infilled by minerals, creating the robust fossil you see today.

Collector Value and Authenticity

This large and exceptionally well-preserved Acanthoceras rhotomagense fossil is a rare find from Sussex, representing an important piece of the UK’s Cretaceous fossil heritage. Its combination of size, preservation quality, and scientific importance ensures it will be a prized addition to any serious fossil collection.

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity, guaranteeing both the accuracy of identification and the integrity of sourcing. This specimen offers not only a fascinating glimpse into Earth’s ancient past but also a striking display piece for collectors, educators, and enthusiasts alike.