Rare Geczyceras bonarelli Ammonite Fossil from Oxfordian Jurassic Italy with Certificate of Authenticity

Description

Geological Context

This exceptional Geczyceras bonarelli ammonite fossil originates from the Oxfordian Stage of the Late Jurassic Period, dating back approximately 163 to 157 million years ago. Found in Italy, this fossil represents a time when vast shallow seas dominated Europe, creating rich marine environments that supported a wide variety of ammonites and other marine invertebrates. The Oxfordian is the earliest age of the Upper Jurassic and is a critical interval in stratigraphy, well known for abundant and diverse ammonite faunas that help define and refine biostratigraphic zones.

Taxonomic Classification

• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Ammonitida
• Superfamily: Perisphinctoidea
• Family: Oppeliidae
• Genus: Geczyceras
• Species: Geczyceras bonarelli

As a member of the Oppeliidae family, Geczyceras exemplifies ammonites with strongly ribbed shells and planispiral forms, making them both scientifically valuable and visually striking.

Morphological Features

This fossil displays several diagnostic characteristics of Geczyceras bonarelli:

• A planispiral shell with relatively compressed whorls.
• Fine ribbing across the flanks, typical of the genus, giving the fossil its distinct texture.
• The venter (outer rim of the shell) may show subtle keeling, a structural trait that provided stability in swimming.
• Well-preserved suture lines, marking chamber divisions, visible in detail on this specimen.

These morphological traits reveal the ammonite’s evolutionary adaptations for buoyancy and hydrodynamic efficiency in open marine environments.

Palaeoenvironment and Depositional Setting

During the Oxfordian, the region that is now Italy was submerged under warm, shallow epicontinental seas, part of the broader Tethys Ocean. This setting was rich in carbonate sedimentation, with limestone and marl deposits frequently preserving ammonites in exceptional detail. The fossil’s preservation indicates deposition in calm marine conditions where fine sediments covered the shells rapidly, protecting them from significant damage.

Scientific and Collector Importance

• Biostratigraphic Value: Geczyceras bonarelli is a significant index fossil of the Oxfordian, aiding in the correlation of strata across Europe.
• Educational Significance: Its distinct ribbing and form make it ideal for teaching about ammonite evolution, palaeoecology, and Jurassic marine systems.
• Collector’s Appeal: With its aesthetic form, scientific importance, and provenance from Italy, this ammonite is a rare and desirable addition to private collections, educational displays, or museum exhibitions.

Authenticity and Presentation

• This specimen is 100% genuine, accompanied by a Certificate of Authenticity.
• The photographs display the exact fossil you will receive—each piece is individually selected for quality.
• A 1 cm scale cube is included in the images for accurate sizing and reference.

This Geczyceras bonarelli ammonite fossil from the Oxfordian Stage of Italy is a striking representation of Late Jurassic marine life. Its strong ribbing, excellent preservation, and historical significance make it an outstanding fossil for serious collectors, educators, and enthusiasts of Earth’s prehistoric past.