Rare Harpoceras exartum Ammonite Fossil, Lower Toarcian Stage Jurassic, Authentic Hurcott Lane Somerset UK Collectors Specimen with COA

Description

Authentic Jurassic Ammonite Fossil

This listing presents a genuine Harpoceras exartum Ammonite Fossil from the Lower Toarcian Stage of the Early Jurassic period, discovered at Hurcott Lane, Somerset, United Kingdom. Ammonites were extinct marine molluscs within the subclass Ammonoidea, closely related to squid and cuttlefish. Their spiral, chambered shells are among the most iconic fossils known, prized by collectors and scientists alike. The specimen offered here has been carefully chosen for its preservation, with photos provided showing the exact ammonite you will receive. A 1 cm scale cube is included for precise sizing.

Geological Context – Lower Toarcian, Jurassic

The Lower Toarcian, dating to approximately 182 million years ago, is one of the most important intervals of the Early Jurassic. It is associated with the Early Toarcian Oceanic Anoxic Event, a significant global environmental shift that impacted marine ecosystems worldwide. Somerset’s Hurcott Lane exposure is part of the world-renowned Jurassic Coast fossil record, offering finely preserved ammonites in marine mudstone deposits.

These rocks represent ancient shallow seas where ammonites thrived in abundance. Fossils from this locality are highly valued in both paleontological research and private collections due to their excellent preservation and precise stratigraphic placement. Ammonites such as Harpoceras exartum serve as index fossils, used by geologists to define distinct biozones within the Toarcian Stage.

Species Profile – Harpoceras exartum

The species Harpoceras exartum belongs to the family Hildoceratidae, within the superfamily Hildoceratoidea, order Ammonitida. Members of this group are easily recognised by their compressed shells, sharp ribbing, and distinct keel along the venter.

Key identifying features of Harpoceras exartum include:

• Strong, well-defined ribbing extending across the flanks to the keel.
• A compressed, planispiral shell with moderately involute coiling.
• A sharp, pronounced keel running along the venter, enhancing hydrodynamic efficiency.
• Suture lines that display the intricate internal chamber structure of ammonites.

These traits not only make Harpoceras exartum a valuable species for stratigraphic studies but also a visually striking fossil specimen for collectors.

Paleoenvironment and Scientific Importance

During the Early Jurassic, Hurcott Lane and the wider Somerset region were submerged beneath warm, shallow epicontinental seas. Ammonites like Harpoceras exartum were nektonic predators, swimming actively in the water column and feeding on small marine animals. After death, their shells settled into the muddy seabed, where fine-grained sediments preserved them in detail.

Because Harpoceras species evolved rapidly and had wide geographic distribution, they are crucial in defining ammonite biozones. Their presence allows paleontologists to precisely date the strata in which they are found, making them indispensable tools for understanding Jurassic geology.

100% Genuine with Certificate of Authenticity

All of our fossils are guaranteed 100% genuine specimens and come with a Certificate of Authenticity. This ammonite is not a replica or cast but an authentic relic of the Lower Toarcian seas, preserved in stone for nearly 182 million years.

A Collector’s and Display Fossil

This Harpoceras exartum ammonite fossil from Hurcott Lane, Somerset, United Kingdom is a rare and important specimen that combines scientific value with natural beauty. Its sharp ribbing, compressed shell, and stratigraphic importance make it a standout addition to any fossil collection, educational display, or natural history showcase.

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