RARE 4″ Dichotomites tardescissus Fossil Ammonite Callovian Jurassic France – Genuine Authentic Prehistoric Marine Cephalopod with COA

Description

Rare Callovian Fossil Ammonite from Normandy, France

This listing offers a rare 4-inch Dichotomites tardescissus fossil ammonite from the Callovian stage of the Jurassic period, found in the famous fossil-bearing deposits of Normandy, France. This remarkable specimen was carefully selected for its well-preserved features, sharp ribbing, and impressive form. The photographs show the actual specimen you will receive, ensuring complete accuracy and authenticity.

Geological Age & Formation

Dichotomites tardescissus lived during the Callovian stage of the Middle Jurassic, approximately 166.1 to 163.5 million years ago. During this period, the Normandy region was covered by warm, shallow epicontinental seas that supported a rich marine ecosystem. Fine sedimentation on the seafloor quickly buried ammonite shells, allowing for exceptional preservation of detail. Normandy’s Callovian deposits are world-renowned for yielding ammonites of exceptional scientific importance and display quality, making this specimen a particularly valuable find.

Species Identification & Morphology

Belonging to the family Perisphinctidae within the superfamily Perisphinctoidea and order Ammonitida, Dichotomites tardescissus is distinguished by its moderately evolute shell, with whorls that display strong, regular ribbing. A notable feature of this species is the bifurcating rib structure, where ribs split into two or more branches as they extend towards the venter (outer edge). This gives the shell a distinctive, finely detailed appearance, ideal for both collectors and educational study. The ribs often curve slightly forward, adding to the elegant yet robust character of the shell. Suture lines—complex, frilled patterns marking the boundaries between shell chambers—are also visible, reflecting the advanced evolutionary development of this genus.

Collector Highlights

• Size: Approximately 4 inches across (scale cube in photographs = 1 cm squares for precise measurement).
• Preservation: Excellent preservation with sharply defined ribbing and clear suture patterns.
• Authenticity: Guaranteed 100% genuine fossil, supplied with a Certificate of Authenticity.
• Display Quality: Well-prepared and aesthetically appealing, suitable for display in a cabinet, study, or educational exhibit.
• Rarity: Dichotomites tardescissus from Normandy is relatively scarce on the fossil market, especially in this level of preservation.

Paleoenvironment & Scientific Significance

In the Callovian seas of the Jurassic, Dichotomites tardescissus thrived as a nektonic predator, actively swimming in mid-water zones to hunt small crustaceans, mollusks, and other invertebrates. Its chambered shell (phragmocone) enabled buoyancy control, allowing it to hover or dive with ease. The finely ribbed, bifurcating shell structure likely played a role in hydrodynamics, streamlining movement and providing structural reinforcement.

As a genus, Dichotomites holds considerable importance in paleontology as an index fossil, meaning it is used to help date and correlate rock layers in the geological record. Its distinctive morphology and well-defined biozone make it a key species for identifying Callovian-aged strata across Europe.

A Prime Addition to Any Fossil Collection

With its combination of rarity, scientific value, and striking visual appeal, this Dichotomites tardescissus ammonite is an outstanding addition for serious fossil collectors, geology enthusiasts, or educators. It represents a fascinating glimpse into the rich marine ecosystems of the Jurassic seas that once covered Normandy.

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity. The fossil pictured is the exact specimen you will receive.