RARE Alocolytoceras robustum Fossil Ammonite Jurassic Upper Toarcian France Genuine Specimen

Description

Rare Alocolytoceras robustum Fossil Ammonite from France

This listing offers a rare and genuine Alocolytoceras robustum Fossil Ammonite, dating from the Upper Toarcian stage of the Jurassic period, discovered in the historic fossil-bearing deposits of T de Balduce, France. Known for its strong shell structure and strikingly preserved morphology, this ammonite represents an extraordinary example of an important Jurassic genus. With its rarity, provenance, and exceptional preservation, it is a highly collectible specimen with both scientific and aesthetic significance.

Every fossil we sell is a carefully chosen piece, and the photographs provided show the exact specimen you will receive. The 1 cm scale cube included in the images ensures accurate size reference. All fossils are 100% genuine specimens and are supplied with a Certificate of Authenticity.

Geological Context and Provenance

This specimen comes from the Upper Toarcian stage of the Lower Jurassic, dating to approximately 178 – 175 million years ago. The Toarcian is a crucial interval in Earth’s history, marked by significant evolutionary diversification of ammonites, as well as important paleoenvironmental changes.

The fossil deposits of T de Balduce in France are internationally renowned for producing exceptionally preserved ammonites. These sediments formed in shallow epicontinental seas, where fine-grained muds and silts created excellent conditions for fossil preservation. Ammonites from this locality provide invaluable insights into Jurassic marine life and biostratigraphy.

Scientific Classification and Identification

This fossil has been identified as Alocolytoceras robustum, a species within the family Lytoceratidae, superfamily Lytoceratoidea, and order Ammonitida. The Lytoceratidae are a highly distinctive group of ammonites, easily recognised by their evolute shells, thin whorls, and elaborately complex sutures.

Alocolytoceras robustum is notable for its sturdier and more robust shell form compared to related species. This adaptation may have provided greater resilience in the open marine environments of the Toarcian seas. Its identification within the Upper Toarcian succession makes it an important marker fossil, useful for correlating strata across different regions of Europe.

Morphology and Distinctive Features

The shell morphology of Alocolytoceras robustum is characterised by:

• Evolute coiling, with all whorls exposed and visible.
• Strong, robust shell structure, giving the species its name.
• Intricate suture patterns, forming deeply indented lobes and saddles across the shell.
• Sleek whorl proportions, reflecting adaptations for buoyancy and efficient swimming.

These features not only make the ammonite scientifically valuable but also highly attractive to collectors, as the robust design combined with ornate sutures creates a visually stunning fossil.

Depositional Environment

The marine sediments of T de Balduce represent shallow sea conditions during the Jurassic. These environments supported rich ammonite faunas, along with other marine invertebrates and reptiles. Periodic low-oxygen conditions contributed to the preservation of ammonite shells, resulting in fossils that retain fine structural detail after nearly 180 million years.

Ammonites such as Alocolytoceras robustum were active swimmers, and their presence in these deposits reflects thriving cephalopod populations in early Mesozoic oceans.

Collectible and Scientific Significance

Specimens of Alocolytoceras robustum are rare, making them highly prized by both private collectors and academic institutions. Their robust morphology and fine preservation make them excellent examples of Jurassic ammonites. Scientifically, they contribute to studies of cephalopod evolution, paleoecology, and Toarcian stratigraphy.

For collectors, this ammonite offers not only an authentic fossil with geological importance but also a natural work of art, its elegant coiling and intricate sutures preserved from deep time.

Key Features of This Fossil

• Rare Alocolytoceras robustum ammonite from T de Balduce, France
• Jurassic (Upper Toarcian stage), approx. 178 – 175 million years old
• Member of the Lytoceratidae family, with robust shell and ornate sutures
• From a classic French fossil locality of scientific importance
• Supplied with a Certificate of Authenticity
• The exact specimen pictured is the one you will receive

This Alocolytoceras robustum Fossil Ammonite is an exceptional specimen, uniting rarity, provenance, and natural beauty in a fossil that truly reflects the richness of Jurassic marine life.