Description
Genuine Pseudopolyplectus appenninicus Ammonite Fossil
This carefully selected specimen is a genuine Pseudopolyplectus appenninicus ammonite fossil from the Toarcian rocks of Aveyron, Occitanie, southern France. It represents an extinct marine cephalopod that inhabited the warm seas covering this region during the latter part of the Early Jurassic, approximately 174–184 million years ago.
With its naturally coiled shell and fine Jurassic character, this fossil offers an attractive combination of visual appeal, geological history and palaeontological interest. It would make an excellent addition to an ammonite collection, French fossil display, geological teaching collection or natural-history cabinet.
The listing photograph shows the actual specimen you will receive. Full sizing and scale information can be seen in the accompanying photograph.
Fossil Classification and Geological Information
Scientific name: Pseudopolyplectus appenninicus
Fossil type: Ammonite
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Hildoceratoidea
Family: Hildoceratidae
Geological period: Jurassic
Epoch: Early Jurassic
Stage: Toarcian
Locality: Aveyron, Occitanie, France
This species is also encountered in palaeontological literature under the combination Polyplectus appenninicus. Such differences can result from changing interpretations of relationships between closely related ammonite genera. It belongs to the Hildoceratidae, an important family of Early Jurassic ammonites that includes numerous forms used to identify and correlate Toarcian marine deposits.
Distinctive Ammonite Morphology
Pseudopolyplectus ammonites are recognised for their compressed, planispirally coiled shells and generally streamlined appearance. The shell consists of a series of progressively larger whorls wound around a central umbilicus. Depending on preservation, the specimen may retain visible ribbing, growth lines, whorl margins or portions of its original ventral profile.
The flanks are typically flattened or gently convex, while the outer edge of the shell may be narrow and defined. Fine ribs or growth lines can curve across the flanks towards the venter, contributing to the elegant form associated with this group. The exact strength and spacing of the ornament can change as an individual grows, making each fossil naturally distinctive.
During life, the ammonite occupied the final and largest part of the shell, known as the body chamber. The older internal portion was divided into a sequence of chambers by walls called septa. These chambers were connected by a slender tube known as the siphuncle, which helped regulate the balance of liquid and gas within the shell and enabled the animal to control its buoyancy.
Complex suture lines formed where the septa met the outer shell wall. When visible, these intricate patterns are among the most characteristic anatomical features of ammonites and help distinguish them from superficially similar coiled cephalopods.
Toarcian Stage of the Early Jurassic
The Toarcian is the final stage of the Early Jurassic Epoch. It followed the Pliensbachian and preceded the Aalenian Stage of the Middle Jurassic. This interval witnessed important environmental changes, fluctuations in sea level and the continued evolution of diverse ammonite lineages throughout European marine basins.
Ammonites are especially valuable as index fossils because they evolved rapidly, were abundant and occupied extensive marine areas. Their changing shell forms allow palaeontologists to divide Jurassic sedimentary successions into zones, subzones and individual faunal horizons. Fossils from different locations can therefore be compared to establish the relative ages of the rocks in which they occur.
A correctly identified Pseudopolyplectus appenninicus provides a direct connection to the Toarcian marine world and the detailed fossil succession used to interpret Early Jurassic geological history.
Jurassic Marine Environment of Aveyron
During the Toarcian, the region now known as Aveyron lay beneath a broad sea connected to the western Tethys Ocean. The modern limestone plateaux and valleys of southern France developed from sediments originally deposited across this ancient marine basin.
Fine carbonate mud, clay and organic material accumulated on the seabed. These deposits supported and preserved a varied ecosystem containing ammonites, belemnites, bivalves, brachiopods, gastropods, crinoids, fish and other marine organisms. Larger vertebrates, including marine reptiles, occupied the surrounding waters.
After death, the ammonite’s shell descended to the seabed or drifted before settling. Rapid burial helped protect it from complete destruction. As additional sediment accumulated, compaction and mineral-rich groundwater gradually transformed the surrounding material into rock. The shell could be mineralised, preserved as a mould or retained as a combination of original and replacement material.
The Toarcian strata of Aveyron are widely appreciated for their diverse ammonite assemblages. Fossils from this region document changing marine communities and provide important evidence for reconstructing Jurassic environments across southern France.
Actual Specimen and Certificate of Authenticity
This is a genuine fossil specimen and not a replica, cast or modern reproduction. It has been individually chosen for its natural appearance, collectable quality and geological interest. Variations in colour, mineralisation, matrix, texture, completeness and surface preservation are authentic features created during fossilisation and subsequent natural weathering.
The photographs form an important part of the listing and show the exact Pseudopolyplectus appenninicus ammonite fossil that will be supplied. Full sizing is provided in the photograph so that the specimen’s dimensions can be assessed before purchase.
The fossil includes a generic Certificate of Authenticity card carrying a lifetime guarantee of authenticity. It is well suited to a Jurassic fossil collection, ammonite display, educational collection or natural-history cabinet and would make a distinctive gift for a fossil collector, geology enthusiast or admirer of prehistoric marine life.
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