Ammonites sternalis Fossil Ammonite Middle Toarcian Jurassic Colnus Aveyron France

Description

Authentic Ammonites sternalis Fossil

This listing offers a genuine Ammonites sternalis fossil ammonite, originating from Colnus, Aveyron, France, and dating to the Middle Toarcian stage of the Jurassic Period, approximately 182–174 million years ago. The fossil has been carefully selected for its preservation and scientific interest. The photos provided show the exact specimen you will receive, with a 1 cm scale cube included for accurate sizing reference. Every fossil we sell is 100% authentic and accompanied by a Certificate of Authenticity.

Geological Setting

The Middle Toarcian is a subdivision of the Early Jurassic, a time marked by widespread marine transgressions and a dynamic evolution of ammonite faunas. The Colnus area in southern France is part of an important Toarcian sequence where fine-grained marine sediments accumulated in shallow seas. These environments produced excellent fossil preservation, allowing the distinctive features of Ammonites sternalis to be captured in detail.

Scientific Classification

• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Ammonitida
• Superfamily: Hildoceratoidea
• Family: Hildoceratidae
• Genus: Ammonites
• Species: Ammonites sternalis

Morphological Features

Ammonites sternalis is notable for its robust, involute shell structure, where the inner whorls are tightly embraced by the outer coils. Its ribbing pattern is a defining trait, with strong, radial ribs extending across the flanks and occasionally bifurcating as they approach the ventral region. The venter is rounded to gently keeled, providing stability in movement. These features not only serve as identification markers for paleontologists but also make this ammonite particularly attractive to collectors due to its symmetrical and aesthetically pleasing form.

Paleoenvironment and Ecology

This ammonite lived in the warm, shallow seas of the Toarcian, an interval marked by fluctuating oxygen levels and evolving marine ecosystems. As a nektonic predator, Ammonites sternalis would have been an active swimmer, preying upon smaller invertebrates such as crustaceans, mollusks, and planktonic organisms. The Colnus region’s depositional environment provided the right conditions to preserve these ammonites, often within fine sediments that protected their shells from extensive damage.

Stratigraphic Importance

Ammonites such as Ammonites sternalis are crucial for biostratigraphy, the science of dating and correlating rock layers using fossil evidence. This species belongs to ammonite zones that help paleontologists precisely define the Middle Toarcian interval. Such precision is vital for reconstructing Jurassic paleoenvironments, sea-level changes, and global events like the Toarcian Oceanic Anoxic Event, which significantly impacted marine life during this time.

Provenance and Authenticity

Collected from Colnus, Aveyron in France, this specimen represents a fine example of a Middle Toarcian ammonite. The locality is well known among paleontologists for yielding high-quality fossils that contribute both to research and to private collections. Every purchase is supported by a Certificate of Authenticity, ensuring peace of mind and guaranteeing the fossil’s provenance.

A Unique Collector’s Specimen

This Ammonites sternalis fossil ammonite offers a chance to own a scientifically important and visually appealing piece of Earth’s history. Its detailed ribbing, excellent preservation, and origin from a classic French locality make it a superb addition to any fossil collection, natural history display, or educational exhibit. It is a genuine relic from the Jurassic seas, representing both natural beauty and scientific value.