Rare Ancolioceras Fossil Ammonite Bajocian Jurassic Horn Park Dorset UK With Certificate of Authenticity

Description

Overview of This Rare Ancolioceras Fossil Ammonite from Horn Park, Dorset

This rare Ancolioceras fossil ammonite is an exceptional specimen from the world-famous Jurassic deposits of Horn Park Quarry in Dorset, United Kingdom. Dating to the Bajocian stage of the Middle Jurassic, this ammonite represents a scientifically important and highly collectible example of British Jurassic paleontology. The fossil has been carefully selected for its preservation, morphology, and display quality. The photographs show the exact specimen you will receive, and full sizing details are provided in the listing images.

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity.

Geological Background and Depositional Environment

Horn Park Quarry—designated as the Horn Park Quarry National Nature Reserve—is the most significant Bajocian ammonite site in Britain and one of the richest in the world. The locality exposes well-bedded limestones deposited during the Middle Jurassic (approximately 170–168 million years ago) in a warm, shallow epicontinental sea that covered much of what is now Dorset.

These sediments accumulated in a calm marine basin with stable conditions, allowing excellent preservation of ammonites and associated fauna. Fossils from this site provide detailed insight into Jurassic biodiversity, sea-level changes, and ammonite evolutionary development. Due to the high scientific importance of Horn Park, access to the site is extremely restricted today, making specimens from this location increasingly rare and highly sought after.

Taxonomy and Scientific Classification

Genus: Ancolioceras

Family: Hildoceratidae

Superfamily: Hildoceratoidea

Order: Ammonitida

Geological Stage: Bajocian (Middle Jurassic)

Locality: Horn Park Quarry, Dorset, United Kingdom

Members of the genus Ancolioceras are known for their distinctive shell morphology and are considered important index fossils within Bajocian biostratigraphy.

Morphological Features and Diagnostic Traits

This Ancolioceras specimen displays several characteristic features that help identify the genus:

• Compressed, finely ribbed shell typical of hildoceratid ammonites
• Strong radial ribbing, extending from the umbilicus to the venter
• Moderately involute coiling, leaving a relatively open umbilicus
• Fine suture patterns, showcasing intricate lobes and saddles
• Graceful shell curvature, reflecting the hydrodynamic shape of mid-level nektonic ammonites

These features suggest an active, free-swimming lifestyle in open marine environments. The fossil retains excellent surface detail, allowing the ribbing and suture lines to be appreciated clearly.

Biostratigraphic and Scientific Importance

Ammonites from Horn Park play a crucial role in understanding:

• Bajocian ammonite zonation
• Middle Jurassic faunal turnover
• Evolutionary relationships within Hildoceratidae
• Correlation of European Jurassic marine strata

The Bajocian is subdivided into several ammonite biozones, and Ancolioceras is an important taxon used by paleontologists for precise stratigraphic classification.

The presence of Ancolioceras in these deposits helps identify specific intervals of the Middle Jurassic, contributing to the global standard ammonite zonation scheme.

Origin and Regional Significance

Horn Park is part of the greater Jurassic Coast region, a UNESCO World Heritage Site famed for its continuous geological record spanning 185 million years. Fossils from this quarry represent some of the clearest and most abundant Bajocian ammonite assemblages known.

Since Horn Park is now protected and closed to public collecting, legally obtained specimens such as this have significant scientific and collector value. Their provenance adds an important layer of authenticity and historical context.

Collectability and Display Appeal

This rare Ancolioceras ammonite is ideal for serious collectors, museums, educators, or enthusiasts of British geology. Its classic morphology, excellent preservation, and prestigious Horn Park origin make it a standout piece for display or research. The fossil’s aesthetic appeal—marked by fine ribbing and balanced shell proportions—ensures it serves as both a scientific specimen and a visually impressive natural artifact.

Authenticity and Customer Assurance

You will receive the exact Ancolioceras ammonite shown in the photographs. Every fossil is professionally examined, legally sourced, and fully verified. Each purchase includes a Certificate of Authenticity confirming its genuine Bajocian age, Horn Park provenance, and accurate scientific identification.