Catasigaloceras planicerclus Ammonite Fossil from Lower Callovian Jurassic Gloucestershire United Kingdom

Description

Geological Context and Provenance

This specimen is a fine example of Catasigaloceras planicerclus, an ammonite from the Lower Callovian Stage of the Jurassic Period, approximately 166 – 163 million years ago. It originates from Gloucestershire, United Kingdom, a county renowned for its rich Jurassic fossil deposits that include ammonites, belemnites, marine reptiles, and other marine fauna. Fossils from this region have been central to stratigraphic studies, helping scientists establish key divisions in the Jurassic time scale.

The Callovian represents part of the Middle Jurassic and is of great importance for both biostratigraphy and palaeontology. Ammonites such as Catasigaloceras planicerclus serve as excellent index fossils, making them crucial for correlating rock layers across Europe and beyond.

Fossil Type and Species Information

Catasigaloceras planicerclus belongs to the Order Ammonitida, Superfamily Stephanoceratoidea, and Family Parkinsoniidae. Ammonites of this family are known for their ornate shells and distinctive ribbing patterns, which make them particularly appealing to collectors and scientists alike.

This species is notable for its relatively flat shell profile, regular ribbing, and evolute coiling, which leaves earlier whorls exposed. These features distinguish Catasigaloceras planicerclus from other contemporaneous ammonites and make it an important taxon within Callovian faunas.

Morphological Features

The fossil displays several defining characteristics:

• Planispiral Shell – Symmetrical coiling in a flat spiral.
• Evolute Coiling – Inner whorls remain visible due to the open nature of the coiling.
• Regular Ribbing – Distinct ribs radiate outward across the flanks and extend over the venter, adding striking ornamentation.
• Flattened Profile – The compressed shell shape is typical of the species name planicerclus.

These features not only aid in identification but also provide aesthetic appeal, as the ribbing and whorl structure create an eye-catching natural design.

Depositional Environment

During the Lower Callovian, Gloucestershire and much of southern England lay beneath shallow epicontinental seas linked to the Tethys Ocean. Warm, relatively calm marine waters supported diverse faunas, with ammonites among the most abundant and ecologically significant organisms.

The sediments in which this specimen was preserved largely consisted of marls and clays, which provided excellent conditions for fossilisation. Such environments facilitated the preservation of fine shell details, allowing ammonites like Catasigaloceras planicerclus to survive in remarkable condition for over 160 million years.

Scientific and Collector Value

Ammonites from Gloucestershire, particularly those from the Callovian, have long been of international importance to palaeontological research. The Catasigaloceras planicerclus is not only scientifically significant but also highly prized among collectors for its distinctive morphology and well-preserved ribbing.

This specimen represents both a piece of natural history and a scientifically valuable index fossil, making it an outstanding choice for display, research, or private collection.

Authenticity and Presentation

• 100% Genuine Specimen – Accompanied by a Certificate of Authenticity.
• Exact Fossil Shown – The photographs provided show the precise specimen you will receive.
• Scale Reference – Scale rule squares / cube = 1 cm. Please consult the images for accurate sizing.

This carefully chosen Catasigaloceras planicerclus ammonite fossil from the Lower Callovian of Gloucestershire offers a rare opportunity to own a genuine Jurassic specimen from a historically important locality, beautifully representing both the artistry of nature and the legacy of Earth’s geological past.