Rare 5.5″ Parkinsonia acris Fossil Ammonite Inferior Oolite Jurassic Coast Burton Bradstock Dorset UK Genuine Specimen with COA

Stunning 5.5″ Parkinsonia acris Ammonite from the Inferior Oolite, Jurassic Coast, Dorset, UK

This magnificent 5.5-inch Parkinsonia acris fossil ammonite was discovered by our own team members, Alister and Alison, on 2 October 2025, at Burton Bradstock, Dorset, United Kingdom, along the renowned Jurassic Coast UNESCO World Heritage Site. Expertly cleaned, prepared, and treated by Alison, the specimen displays exceptional preservation and intricate ribbing. Originating from the Inferior Oolite Formation, it dates to the Middle Jurassic Period (Bajocian Stage, approximately 170–168 million years ago). This ammonite is both scientifically valuable and visually striking — a perfect example of the marine life that flourished in the ancient seas of Jurassic Britain.

Geological and Depositional Context

The Inferior Oolite Formation is one of southern England’s most famous fossil-bearing rock units. Composed of oolitic limestones, marls, and fine bioclastic sediments, it was deposited in a warm, shallow sea during the Bajocian Stage of the Middle Jurassic. The Burton Bradstock section, part of the Jurassic Coast, represents an important outcrop where these richly fossiliferous strata are beautifully exposed.
During the Jurassic, the Dorset coastline was located near the equator, submerged beneath clear, sunlit waters teeming with ammonites, belemnites, brachiopods, and early marine reptiles. Sedimentation was slow and stable, allowing the fine preservation of delicate shells such as those of Parkinsonia acris. The oxygen-rich, carbonate-dominated seabed helped encapsulate organisms rapidly, protecting their structure from decay and producing the stunning fossil record we see today.

Species Overview – Parkinsonia acris

Parkinsonia acris belongs to the family Parkinsoniidae, superfamily Perisphinctoidea, order Ammonitida. This species is one of the most recognisable ammonites of the Bajocian Stage and serves as a biostratigraphic index fossil for its age. It is characterised by a moderately involute, compressed shell with fine, dense ribbing that bifurcates toward the outer whorl. The ribs sweep gracefully across the flanks, producing a delicate and balanced symmetry. The name Parkinsonia commemorates James Parkinson, the pioneering English geologist and paleontologist whose studies of fossils helped establish modern stratigraphy.
P. acris typically occurs in the Parkinsonia Biozone, a key subdivision of the Inferior Oolite that helps define the middle Bajocian sequence across Europe. Its refined morphology reflects a free-swimming lifestyle in mid-water marine environments, using its coiled shell as a buoyancy aid while hunting for small crustaceans and plankton.

Scientific and Historical Importance

Ammonites of the genus Parkinsonia are of particular interest to paleontologists due to their short stratigraphic range and wide distribution, making them ideal for correlating Jurassic sediments globally. The species P. acris is especially important in establishing the Parkinsonia acris Zone, a well-documented stage marker in European Jurassic geology. Fossils of this species from the Inferior Oolite of Dorset are prized for their clarity and beauty, with preservation often revealing fine surface ornamentation and original shell structure.
Historically, Parkinsonia acris was one of the ammonites that helped geologists in the 19th century divide the Jurassic strata into distinct biostratigraphic zones — a revolutionary concept that remains central to geological science today.

Condition, Provenance, and Authenticity

This specimen is 100% genuine and has been professionally cleaned and stabilised to reveal its finest details. The coiling, ribbing, and whorl structure are crisp and natural, exhibiting the diagnostic features of Parkinsonia acris. No artificial restoration has been applied. The fossil was collected by our own field team and prepared by Alison with expert care.
The photograph shows the exact specimen you will receive, ensuring full transparency and authenticity. Included with your purchase is a Certificate of Authenticity, verifying the fossil’s species, provenance, age, and formation.

Details at a Glance

• Species: Parkinsonia acris

• Family: Parkinsoniidae

• Superfamily: Perisphinctoidea

• Order: Ammonitida

• Age: Bajocian Stage, Middle Jurassic (~170–168 million years ago)

• Biozone: Parkinsonia acris Zone

• Formation: Inferior Oolite

• Locality: Burton Bradstock, Dorset, United Kingdom

• Discovered by: Alister and Alison on 02 October 2025

• Prepared by: Alison

• Condition: Professionally cleaned and stabilised; excellent preservation

• Scale: Cube = 1 cm (see photo for full sizing)

• Included: Certificate of Authenticity

A Prestigious Collector’s Fossil from Britain’s Jurassic Heritage

This Parkinsonia acris ammonite represents the finest quality from Dorset’s Inferior Oolite. Its well-preserved form, scientific importance, and provenance from the Jurassic Coast make it a standout piece for collectors, educators, or anyone inspired by the natural history of our planet’s ancient seas.