Rare Pseudomercaticeras parvilobum Fossil Ammonite, Jurassic, Upper Toarcian, Wilts UK, Genuine Specimen with COA

Description

Offered here is a Rare Fossil Ammonite of Pseudomercaticeras parvilobum from the Upper Toarcian Stage of the Jurassic Period, collected in Wiltshire, United Kingdom. This ammonite is an uncommon and scientifically significant species from a pivotal interval in Jurassic ammonite evolution.

You will receive the exact fossil shown in the photographs — selected for its quality, preservation, and diagnostic features.

Scale Rule Squares / Cube = 1cm — please see images for accurate sizing and details.

Key Geological and Scientific Information:

• Species: Pseudomercaticeras parvilobum
• Fossil Type: Ammonite (extinct marine cephalopod)
• Geological Period: Jurassic
• Geological Stage: Upper Toarcian (~182 million years ago)
• Location: Wiltshire, England, UK
• Order: Ammonitida
• Superfamily: Hildoceratoidea
• Family: Mercaticeratidae
• Described By: Buckman (early 20th century)

Morphology Features:

Pseudomercaticeras parvilobum is characterised by its moderately involute shell, with finely ribbed and gently compressed whorls. Ribs are dense, regularly spaced, and tend to fade near the venter, which is narrowly rounded. The shell often shows a smooth outer band and a well-defined umbilicus. These features contribute to its recognition and make it an excellent example of late Toarcian ammonite morphology.

This particular specimen displays all the key traits of the species and is an excellent reference fossil.

Depositional Environment:

The fossil likely originated from fine-grained marine mudstones or laminated shale deposited in low-energy offshore basins during the Toarcian Oceanic Anoxic Event — a time when organic-rich sediments accumulated in restricted marine environments across Europe.

These conditions contributed to exceptional preservation of marine organisms, particularly ammonites.

Stratigraphic Context & Biozone:

Pseudomercaticeras parvilobum is found within the Pseudomercaticeras parvilobum Subzone of the Variabilis Zone (Upper Toarcian). This makes it a key index fossil for refining stratigraphic correlation within European Jurassic sequences, particularly in southern Britain and western Europe.

Scientific Importance:

This ammonite is part of a group that emerged during major evolutionary transitions in the Hildoceratoidea lineage, following the peak of the Toarcian Oceanic Anoxic Event. As such, it provides valuable data for both biostratigraphic and paleoenvironmental studies, and is seldom found in collections with this level of preservation.

Authenticity Guarantee:

All our fossils are 100% genuine specimens, carefully sourced and expertly prepared. Each fossil comes with a Certificate of Authenticity, documenting its identification, origin, and geological age.

This Pseudomercaticeras parvilobum ammonite is a rare and scientifically meaningful specimen — ideal for collectors, researchers, educators, and anyone passionate about Jurassic marine life and the ammonite evolutionary record.