Graphoceras marginatum Fossil Ammonite Aalenian Jurassic Dorset UK Genuine Louse Hill Quarry Sherborne Ammonite with COA

Description

Authentic Graphoceras marginatum Fossil Ammonite

This specimen is a beautifully preserved Graphoceras marginatum ammonite fossil from the Aalenian stage of the Middle Jurassic, collected at Louse Hill Quarry, Sherborne, Dorset, United Kingdom. This ammonite is an excellent example of a zone-defining species, highly valued for both its scientific importance and display quality. The photographs show the exact fossil you will receive, with a 1 cm scale cube and rule squares included for precise size reference. Every specimen is 100% genuine and supplied with a Certificate of Authenticity.

Geological Context – Aalenian of Dorset

The Aalenian stage, spanning approximately 174.1 to 170.3 million years ago, marks the beginning of the Middle Jurassic period. Fossils from this stage are especially significant, as they represent a time of diversification in ammonites and other marine organisms. The Louse Hill Quarry in Sherborne, Dorset, is a classic British locality known for its well-preserved Aalenian ammonite faunas. These fossils were deposited in shallow marine environments dominated by limestone and marl sediments, preserving fine details of shell morphology. Dorset, as part of the wider Jurassic Coast region, is globally recognised for its exceptional fossil heritage, making this specimen part of a broader scientific legacy.

Species Overview – Graphoceras marginatum

The genus Graphoceras belongs to the family Graphoceratidae within the order Ammonitida, superfamily Hildoceratoidea. The species Graphoceras marginatum is one of the most important ammonites of the Aalenian, serving as an index fossil for the Marginatum Zone. Its presence allows precise correlation of rock strata across Europe, making it vital for Jurassic stratigraphy. Fossils of this ammonite are relatively rare compared to later Jurassic genera, adding to their desirability among collectors.

Morphological Features

Graphoceras marginatum is characterised by its compressed shell, involute coiling, and strongly ribbed whorls. The ribs extend radially across the flanks, creating a striking ornamentation that helps to distinguish it from related genera. The venter (outer margin) is relatively narrow, and the shell profile gives an elegant appearance, with ribs sometimes bifurcating as they approach the outer edge. This fossil preserves these defining traits with clarity, showcasing the intricate ribbing that made Graphoceras such an effective stratigraphic marker.

Scientific and Collectible Value

The importance of Graphoceras marginatum lies not only in its aesthetic form but also in its role as a zone fossil of the Aalenian Marginatum Biozone. Its discovery in well-documented localities such as Louse Hill Quarry provides geologists and palaeontologists with a reliable tool for dating Jurassic deposits. Collectors value this ammonite for its rarity, historical significance, and the fact that it represents a transitional stage in ammonite evolution during the Middle Jurassic. For educators and students, it offers a tangible link to the methods used in geological dating and correlation.

Provenance and Guarantee

This specimen comes from Louse Hill Quarry, Sherborne, Dorset, a site long recognised for its ammonite faunas. It has been carefully chosen for its preservation and clarity of diagnostic features. As with all of our fossils, it is accompanied by a Certificate of Authenticity, guaranteeing that it is a genuine specimen. The exact fossil in the photographs is the one you will receive.

A Rare Ammonite from the Aalenian of Dorset

This Graphoceras marginatum ammonite fossil from Louse Hill Quarry, Sherborne is an exceptional specimen, representing both scientific value and display quality. With its finely ribbed shell and its importance as an index fossil of the Aalenian stage, it is a rare opportunity to own a piece of Jurassic history from one of Britain’s most important fossil localities.