RARE Gulielmiceras castor Fossil Ammonite Iridescent Callovian Jurassic Russia

Description

Rare Gulielmiceras castor Fossil Ammonite

This listing offers a rare Gulielmiceras castor fossil ammonite, preserved in striking detail from the Callovian stage of the Jurassic period. Originating from the fossil-rich deposits of Ryazan, Russia, this ammonite is approximately 166 – 163 million years old and displays remarkable natural iridescence. The shimmering nacre highlights the exquisite preservation of this specimen, making it both a scientifically significant fossil and a highly desirable collector’s piece.

The specimen pictured is the exact ammonite you will receive, ensuring complete transparency and confidence in your purchase. A 1 cm scale cube is shown in the images for accurate size reference. Every fossil comes with a Certificate of Authenticity, confirming it is a genuine specimen.

Geological Context and Provenance

This fossil originates from the Callovian stage of the Middle Jurassic, a time when ammonites flourished in the shallow seas that once covered much of Europe and Russia. The Ryazan region is particularly renowned for producing exceptionally preserved ammonites with fine morphological details and often with a nacreous, iridescent surface.

The Callovian seas were nutrient-rich environments, supporting a wide array of marine life including ammonites, belemnites, bivalves, and marine reptiles such as pliosaurs and ichthyosaurs. Ammonites like Gulielmiceras castor serve as important index fossils, helping geologists correlate rock layers across vast regions.

Scientific Classification

• Genus: Gulielmiceras
• Species: Gulielmiceras castor
• Order: Ammonitida
• Superfamily: Stephanoceratoidea
• Family: Kosmoceratidae

This genus belongs to the Kosmoceratidae, a family of ammonites known for their ornate shell morphology, distinctive ribbing, and well-developed ornamentation. These features make them easily recognisable and highly valuable for both collectors and paleontologists.

Morphological Features

The Gulielmiceras castor ammonite exhibits several distinct traits characteristic of its genus and family:

• Evolute shell structure, with outer whorls exposing earlier ones.
• Strong ribbing and ornamentation, giving the shell a striking texture.
• Complex suture lines, intricately folded and highly diagnostic of the Kosmoceratidae.
• Iridescent nacre, a natural feature of the fossilised shell, producing shimmering hues of green, blue, and red when viewed under light.

These features not only provide insight into the evolutionary development of ammonites but also enhance the fossil’s aesthetic appeal.

Ecological and Evolutionary Significance

Ammonites like Gulielmiceras castor were marine cephalopods, closely related to modern squid, cuttlefish, and octopuses. Their coiled shells served as buoyancy chambers, enabling them to move through the water with precision. They were active predators, feeding on small crustaceans, mollusks, and other marine organisms.

As important components of the Middle Jurassic ecosystem, ammonites occupied a crucial role in the food chain. Their widespread distribution and rapid evolution make them key fossils for dating Jurassic sediments, helping researchers to reconstruct ancient marine environments and evolutionary pathways.

Collector’s Value and Display

This Gulielmiceras castor fossil ammonite is not only a valuable scientific specimen but also a beautiful natural display piece. Its iridescent surface enhances its uniqueness, transforming it into a striking addition to any collection. Collectors appreciate these fossils for their rarity, geological importance, and visual appeal, while educators and enthusiasts value them as tangible evidence of Earth’s prehistoric past.

With its combination of rarity, preservation, and aesthetic qualities, this ammonite represents an excellent opportunity to own a genuine piece of Jurassic history.

Key Details

• Species: Gulielmiceras castor
• Age: Jurassic, Callovian (166 – 163 million years old)
• Origin: Ryazan, Russia
• Family: Kosmoceratidae
• Features: Iridescent nacre, evolute shell, strong ribbing, complex sutures
• Certificate of Authenticity included
• Exact specimen pictured with 1 cm scale cube for reference

This is a rare and highly collectible ammonite fossil, offering both scientific value and natural beauty. A timeless addition to any fossil or natural history collection.