Hildoceras Ammonite Fossil Jurassic Yorkshire UK Genuine Specimen with Certificate of Authenticity

Hildoceras Ammonite Fossil – Jurassic, Yorkshire, UK

This genuine Hildoceras ammonite fossil originates from the celebrated Jurassic deposits of Yorkshire, United Kingdom. Carefully selected for quality and visual appeal, the photograph provided shows an example of the actual specimen you will receive. Full sizing please see photo for precise measurements and scale. Each fossil includes a Certificate of Authenticity lifetime guarantee generic card, confirming its authenticity and natural geological origin.

Yorkshire’s coastline, particularly around Whitby and the Cleveland Basin, is internationally renowned for producing exceptionally preserved Jurassic ammonites. Hildoceras is one of the most distinctive and scientifically important genera from these strata, prized by collectors and widely referenced in geological research.

Geological Age and Stratigraphic Context

Hildoceras is characteristic of the Lower Jurassic, specifically the Toarcian Stage, approximately 183–174 million years ago. It is especially associated with the Hildoceras bifrons Biozone, an important subdivision of the Toarcian used for precise stratigraphic correlation across Europe.

In Yorkshire, these fossils are typically found within dark marine shales formed in offshore environments. During the Toarcian, northern England lay beneath a warm, shallow sea. Fine mud sediments accumulated slowly on the seabed, creating ideal conditions for preserving marine life. Periodic low-oxygen events in the deeper parts of the basin reduced scavenging and decay, contributing to the excellent fossil record for which the region is famous.

Fossil Type and Preservation

This specimen represents the mineralised shell of an extinct marine cephalopod. Hildoceras possessed a tightly coiled, planispiral shell composed originally of aragonite. Over millions of years, burial and mineral replacement preserved the shell form within the surrounding rock matrix.

Typical morphological features of Hildoceras include:

• A moderately involute, compressed shell form

• Fine, evenly spaced ribbing across the whorls

• A smooth or slightly keeled venter

• Complex suture patterns marking internal chamber divisions

The internal chambers were separated by septa and connected by a siphuncle, allowing the living animal to regulate buoyancy. These structural adaptations enabled ammonites to occupy a range of ecological niches within the Jurassic seas.

Taxonomy and Scientific Importance

Hildoceras belongs to:

• Class: Cephalopoda

• Subclass: Ammonoidea

• Order: Ammonitida

• Superfamily: Hildoceratoidea

• Family: Hildoceratidae

The genus Hildoceras was formally described in the 19th century and has since become one of the most important index fossils for the Lower Jurassic. The Hildoceras bifrons Zone is widely recognised in European stratigraphy and plays a crucial role in correlating Toarcian rock layers across different regions.

Ammonites such as Hildoceras were active nektonic predators or opportunistic feeders, related to modern squid and cuttlefish but protected by an external chambered shell. Their rapid evolutionary rates and broad geographic distribution make them invaluable for geological dating and paleoenvironmental reconstruction.

Depositional Environment of Jurassic Yorkshire

During the Toarcian Stage, Yorkshire was submerged beneath a broad epicontinental sea connected to the Tethys Ocean. Fine-grained sediments settled in relatively calm waters, forming the laminated shales seen today. These environments were rich in marine biodiversity, including ammonites, belemnites, bivalves, and marine reptiles.

The preservation of Hildoceras within these sediments provides a direct connection to this ancient marine ecosystem, offering insight into ocean chemistry, climate fluctuations, and evolutionary change during the Early Jurassic.

Authenticity and Presentation

This Hildoceras ammonite fossil is a genuine Jurassic specimen from Yorkshire, UK. It has been carefully chosen to provide a clear and attractive example of this classic British ammonite. The image supplied shows an example of the actual fossil you will receive. Full sizing please refer to the photo.

Each fossil includes a Certificate of Authenticity lifetime guarantee generic card, ensuring long-term confidence in its authenticity and provenance.

A superb addition to any fossil collection, geological display, or educational setting, this Hildoceras ammonite represents an iconic species from the Jurassic seas of Yorkshire.