Description
Rare Kosmoceras guliellm Ammonite Fossil from Ryazan, Russia
This is a genuine Kosmoceras guliellm ammonite fossil from the Callovian stage of the Middle Jurassic, discovered in the Ryazan region of Russia. Estimated at approximately 166–163 million years old, this striking fossil comes from one of the most famous ammonite-bearing deposits in Europe. The specimen shown in the photos is the exact one you will receive, displayed with a 1 cm scale cube for accurate sizing. Every fossil we sell comes with a Certificate of Authenticity, providing full assurance of its genuineness and provenance.
Geological Context – Callovian Stage of the Jurassic
The Callovian stage marks a pivotal interval in the Middle Jurassic, spanning from about 166 to 163 million years ago. During this period, the seas covering present-day Russia were part of an expansive epicontinental shelf, rich in marine life and sediments that preserved organisms in exquisite detail.
The Ryazan area is particularly well-known for its richly fossiliferous clays and marls, which yield an abundance of ammonites belonging to the genus Kosmoceras. These deposits provide important insight into Jurassic paleoenvironments, documenting warm, shallow seas filled with ammonites, belemnites, bivalves, and marine reptiles. Fossils from this region continue to play a crucial role in stratigraphic correlations across Europe and beyond.
Scientific Classification
- Genus: Kosmoceras
- Species: Kosmoceras guliellm
- Family: Kosmoceratidae
- Superfamily: Stephanoceratoidea
- Order: Ammonitida
- Geological Stage: Callovian, Middle Jurassic (c. 166–163 million years ago)
- Locality: Ryazan, Russia
Morphological Features of Kosmoceras guliellm
Kosmoceras ammonites are among the most distinctive and ornate ammonites of the Jurassic. The Kosmoceras guliellm displays several key features that make it particularly collectible:
- Strong ribbing across the shell, producing a bold sculptural appearance.
- Pronounced tubercles (nodes) along the whorl, adding to its robust texture.
- Relatively involute coiling, with inner whorls partly covered by the outer whorl.
- A shell that often exhibits beautiful three-dimensional preservation, making these specimens ideal both for display and study.
- The sutures, highly complex and deeply folded, reflect the evolutionary advancement of Jurassic ammonites.
These aesthetic and scientific qualities make Kosmoceras fossils highly prized by collectors worldwide.
Paleontological Importance
Kosmoceras species, including Kosmoceras guliellm, are significant as index fossils, enabling geologists to subdivide the Callovian stage into finer biostratigraphic zones. Their restricted temporal distribution and broad geographic presence allow for precise correlation of Jurassic rocks across large areas of Europe and Russia.
The genus Kosmoceras is also notable for its extraordinary diversity and variation, illustrating the adaptive radiation of ammonites in the Middle Jurassic seas. This fossil represents not just a beautiful object, but also a key to unlocking Earth’s deep geological history.
Paleoecology and Ancient Environment
Ammonites like Kosmoceras guliellm were active predators and swimmers in the Jurassic oceans, part of the cephalopod lineage that includes modern squid, octopus, and nautilus. They likely fed on small crustaceans, molluscs, and planktonic organisms, using their tentacles to seize prey.
The depositional environment in which this fossil was preserved would have been a shallow, warm marine basin, with fine muds and silts settling to the seafloor. These sediments provided the perfect conditions to encapsulate and preserve ammonite shells in remarkable detail, ensuring that specimens survive today as windows into the ancient past.
Collector and Display Value
A Kosmoceras guliellm ammonite fossil from Ryazan is more than a collector’s piece; it is a fusion of natural beauty and scientific heritage. Its striking ribbed and tubercled form makes it an eye-catching specimen for display, while its documented Callovian age links it directly to the geological timescale.
Collectors, educators, and enthusiasts alike value these fossils for their rarity, historical importance, and aesthetic appeal. This specimen represents a genuine opportunity to own a fossil that combines ornamental elegance with paleontological significance.
Key Details
- Fossil Type: Ammonite
- Species: Kosmoceras guliellm
- Age: Callovian Stage, Middle Jurassic (c. 166–163 million years old)
- Locality: Ryazan, Russia
- Supplied with a Certificate of Authenticity
- Exact specimen shown in photographs with 1 cm scale cube
This is a rare and scientifically valuable specimen of Kosmoceras guliellm ammonite fossil, offering a unique glimpse into the Jurassic seas of Russia and an extraordinary addition to any fossil collection.
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