Rare Cliestosphinctes paucicosta Ammonite Fossil, Upper Bajocian Stage Jurassic, Authentic Evrecy Calvados France Collectors Piece with COA

Description

Authentic Jurassic Ammonite Fossil

This listing offers a genuine Cliestosphinctes paucicosta Ammonite Fossil from the Upper Bajocian Stage of the Jurassic, discovered in Evrecy, Calvados, France. Ammonites were extinct cephalopods of the subclass Ammonoidea, closely related to squid and cuttlefish. Their spiral shells, divided into chambers, make them among the most recognisable and desirable fossils worldwide. This specimen has been carefully chosen for both its scientific value and collector appeal. The photographs show the exact ammonite you will receive, with a 1 cm scale cube included for accurate size reference.

Geological Context – Upper Bajocian, Jurassic

The Bajocian Stage of the Middle Jurassic, dated to approximately 170–168 million years ago, was a time of dynamic marine environments and rapid ammonite diversification. The Upper Bajocian in particular is renowned for its rich ammonite faunas, which serve as precise stratigraphic markers.

The Calvados region of Normandy, France, is celebrated for its fossil-rich exposures, especially ammonites that preserve exquisite details of Jurassic marine ecosystems. Ammonites such as Cliestosphinctes paucicosta are invaluable index fossils, helping geologists date and correlate Jurassic strata across Europe and beyond.

Species Profile – Cliestosphinctes paucicosta

The species Cliestosphinctes paucicosta belongs to the family Perisphinctidae, within the superfamily Perisphinctoidea and order Ammonitida. Members of this genus are characterised by their distinctive shell morphology and ribbing patterns, making them diagnostic fossils for Bajocian-aged rocks.

Key identifying features of Cliestosphinctes paucicosta include:

• A moderately evolute shell, with visible inner whorls.
• Relatively few ribs (“paucicosta” literally meaning “few-ribbed”), giving the shell a smoother appearance compared to heavily ribbed ammonites.
• Ribs that are simple and strong, extending across the flanks and over the venter.
• A rounded to slightly flattened venter, often without a keel.
• Wide umbilicus, exposing earlier coils clearly.

These morphological traits distinguish C. paucicosta from other Bajocian ammonites and make it an important fossil for both scientific study and display collections.

Paleoenvironment and Scientific Importance

During the Bajocian, the area around Evrecy in Normandy was covered by shallow, warm seas connected to the Tethys Ocean. This environment supported abundant marine life, including ammonites, belemnites, bivalves, and marine reptiles. Ammonites like Cliestosphinctes paucicosta thrived as nektonic predators, actively swimming and preying on smaller marine invertebrates.

When these animals died, their shells settled to the seabed and were buried in sediment. Over millions of years, mineralisation preserved their forms, leaving behind the fossils we find today. The presence of C. paucicosta in Upper Bajocian deposits provides paleontologists with crucial information about ammonite evolution, paleoecology, and the biostratigraphy of the Jurassic seas of Europe.

100% Genuine with Certificate of Authenticity

All of our fossils are guaranteed 100% genuine specimens and include a Certificate of Authenticity. This ensures that your ammonite fossil is an authentic piece of natural history and not a cast or replica.

A Collector’s and Display Fossil

This Cliestosphinctes paucicosta ammonite fossil from the Upper Bajocian of Evrecy, Calvados, France is a remarkable piece for collectors, educators, and enthusiasts of paleontology. Its distinctive morphology, clear provenance, and historical significance make it an excellent specimen for any fossil collection or natural history display.

Scale Rule Squares / Cube = 1 cm. Please see listing photos for the full sizing of this exact specimen.