Iridescent Pterolytoceras Ammonite Fossil Valanginian Cretaceous Madagascar Genuine Certified

Description

Authentic Iridescent Pterolytoceras Ammonite Fossil from Madagascar

This striking Pterolytoceras ammonite fossil originates from Madagascar and dates to the Valanginian stage of the Early Cretaceous period (approximately 139–133 million years ago). The specimen exhibits stunning natural iridescence, a feature highly prized by collectors and enthusiasts. This shimmering nacre, often referred to as ammolite when used in jewellery, formed as the aragonite shell layers of the ammonite fossilised under specific conditions. The result is a fossil that is both scientifically significant and visually captivating. The piece comes with a Certificate of Authenticity and is photographed with a 1 cm scale cube to give accurate size reference. The exact fossil shown in the photo is the specimen you will receive.

Geological Background – Valanginian Stage of the Cretaceous

The Valanginian stage represents the second age of the Early Cretaceous, a time when shallow epicontinental seas covered much of what is now Madagascar. This environment fostered an abundance of marine life, including ammonites, belemnites, and early marine reptiles. Fossils from this period are vital for reconstructing the evolutionary pathways of cephalopods and their adaptations to dynamic ecosystems. The preservation of iridescent ammonites in Madagascar reflects unique mineralogical conditions, where low-oxygen depositional settings prevented decay and preserved delicate shell structures in extraordinary detail.

Scientific Classification

• Class: Cephalopoda
• Subclass: Ammonoidea
• Order: Ammonitida
• Superfamily: Lytoceratoidea
• Family: Lytoceratidae
• Genus: Pterolytoceras

This genus belongs to the Lytoceratidae, known for their distinctive coiling, smooth to gently ribbed shells, and often elaborate suture lines. Members of this group are considered important for biostratigraphy, helping geologists to precisely date rock layers within the Early Cretaceous.

Morphological Features and Iridescence

The shell of Pterolytoceras is characterised by its evolute coiling, with whorls that are not tightly overlapped, giving the ammonite a wide and open appearance. The sutures are often complex, providing further detail for scientific study. What makes this specimen particularly remarkable is its natural iridescence, produced by microscopic layering of aragonite crystals within the shell. When light strikes the fossil, it refracts through these layers, creating a rainbow-like display of reds, greens, blues, and golds. This optical effect is entirely natural and unique to each specimen.

Depositional Environment

During the Valanginian, Madagascar was part of the southern hemisphere’s warm tropical seas. These ammonites lived as active swimmers, using jet propulsion to pursue prey such as small crustaceans and plankton. The sediments that entombed them were laid down under relatively calm marine conditions, allowing shells to be preserved intact. The combination of rapid burial, mineral-rich waters, and low oxygen created the conditions necessary for the exceptional preservation of iridescence, making specimens like this both rare and scientifically invaluable.

Collector and Display Value

An iridescent Pterolytoceras ammonite fossil is more than just a fossil—it is a natural work of art formed over 130 million years ago. Its play of colour makes it an exceptional display piece, whether showcased in a private collection, a natural history display, or as an educational resource. Collectors prize Madagascar ammonites for their vibrant iridescence, which sets them apart from most other fossil localities worldwide.

This fossil is guaranteed 100% genuine, carefully selected for its quality, rarity, and aesthetic appeal. With its scientific significance, stunning iridescence, and geological history rooted in the Valanginian seas of Madagascar, it is a truly extraordinary specimen to own.