Rare Stephanoceras umbilicum Fossil Ammonite Bajocian Jurassic Oborne Wood Sherborne Dorset UK Genuine Specimen with COA

Description

Magnificent Stephanoceras umbilicum Ammonite from the Bajocian, Dorset, UK

This exceptional Stephanoceras umbilicum fossil ammonite was discovered in the Bajocian Stage of the Middle Jurassic, approximately 170–168 million years old, from Oborne Wood, near Sherborne, Dorset, United Kingdom. It represents one of the most iconic and scientifically significant ammonites of the Middle Jurassic, prized for its intricate ribbing and characteristic shell morphology. Specimens of this quality from Dorset are rare, making this fossil an outstanding addition for collectors and researchers alike.

Geological and Depositional Context

During the Bajocian, southern England was submerged beneath a warm, shallow epicontinental sea teeming with marine life. Sediments from this period, forming part of the Inferior Oolite and associated formations, accumulated in low-energy offshore environments where fine limestones and calcareous muds preserved marine organisms in remarkable detail.

The fossil-bearing strata at Oborne Wood, Sherborne, belong to the Middle Jurassic succession of Dorset, an internationally recognised fossil region known for its ammonite diversity and stratigraphic precision. The Bajocian Stage was a pivotal interval in ammonite evolution, with the family Stephanoceratidae flourishing across Europe’s marine basins and serving as a key biostratigraphic indicator.

Species Overview – Stephanoceras umbilicum

Stephanoceras umbilicum is a distinguished species within the family Stephanoceratidae, superfamily Stephanoceratoidea, order Ammonitida. It is easily recognised by its large, evolute shell with a wide umbilicus, strong ribbing, and well-developed tubercles along the ventrolateral margins. The ribs typically bifurcate or trifurcate towards the outer whorl, creating a visually striking, ornate pattern characteristic of the genus Stephanoceras.

This species is a hallmark fossil of the Garantiana Biozone of the Lower Bajocian, making it a valuable index species for correlating Jurassic sequences throughout the northwest European province. The specimen’s intricate sculpture reflects an adaptive balance between hydrodynamic efficiency and shell strength, suited to life as an agile, free-swimming cephalopod in open marine waters.

Scientific and Historical Significance

Ammonites of the genus Stephanoceras hold immense paleontological value, marking a critical evolutionary lineage within Middle Jurassic cephalopods. They provide insight into Jurassic marine ecosystems and evolutionary radiation patterns following earlier extinction events. The wide geographic range of S. umbilicum and its stratigraphic importance make it one of the most studied ammonite taxa in British Jurassic geology.

The Oborne Wood locality near Sherborne has long been associated with well-preserved Bajocian fossils, contributing significantly to biostratigraphic frameworks established by 19th- and 20th-century British geologists. Specimens like this one exemplify the exceptional fossil record of Dorset’s inland Jurassic sites, complementing the globally renowned coastal exposures of the Jurassic Coast.

Condition, Authenticity, and Display

This 100% genuine fossil specimen has been carefully selected for its superb definition and natural form. The whorls exhibit crisp ribbing and finely preserved tubercles typical of Stephanoceras umbilicum. It has undergone gentle preparation to reveal detail while preserving the integrity of the original shell structure.

The photograph shows the exact specimen you will receive, not a representative example, ensuring complete transparency. A Certificate of Authenticity is included, confirming the fossil’s identity, geological provenance, and genuine origin.

Details at a Glance

• Species: Stephanoceras umbilicum
• Family: Stephanoceratidae
• Superfamily: Stephanoceratoidea
• Order: Ammonitida
• Age: Bajocian Stage, Middle Jurassic (~170–168 million years ago)
• Formation: Inferior Oolite Group
• Locality: Oborne Wood, Sherborne, Dorset, United Kingdom
• Condition: Genuine, well-preserved fossil ammonite; gently cleaned and prepared
• Scale: Cube = 1 cm (see photos for exact sizing)
• Included: Certificate of Authenticity

A Collector’s Piece of Jurassic Elegance

This Stephanoceras umbilicum ammonite embodies the beauty and complexity of Jurassic marine life. Its ornate ribbing, scientific importance, and provenance from a classic British fossil locality make it a highly desirable specimen for any serious collector or lover of natural history. A true testament to Earth’s deep past, preserved in stone for over 170 million years.