Fossils for Sale - High-quality BRITISH and WORLDWIDE Fossils. An impressive selection of fossils, including Ammonites, Trilobites, Belemnites, Fossil Fish, Fossil Shark Teeth, Fossilised Insects in Amber, Dinosaurs, and Reptiles. UK Fossils was formed in 1988 and collects and preps our own fossils in the heart of the Jurassic Coast, collecting fossils from Lyme Regis, Charmouth and Somerset. Our passion for fossils is reflected in our carefully curated collection, which includes some of the rarest and most unique specimens available.

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Arnioceras Fossil Ammonite Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen with COA
Arnioceras Fossil Ammonite Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen with COA - Image 2

Arnioceras Fossil Ammonite Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen with COA

£42.00

Authentic Arnioceras Fossil Ammonite from the Jurassic Coast, Dorset

This superb Arnioceras Fossil Ammonite originates from the Black Ven Marls of the Lower Lias Formation, part of the Jurassic Coast at Black Ven, Lyme Regis, Dorset, UK. Discovered by our own fossil collectors Alister and Alison on 05 November 2025, this genuine specimen has been expertly cleaned, prepped, and treated by Alison to reveal its intricate structure and natural beauty. Dating to approximately 195–200 million years ago, during the Early Jurassic (Sinemurian) Stage, this ammonite captures a fascinating moment in geological history when life was diversifying rapidly in the warm, shallow seas that once covered southern England.

Geological and Scientific Context

Arnioceras belongs to the family Arietitidae, within the superfamily Psiloceratoidea, and forms part of the order Ammonitida—an extinct group of cephalopods closely related to modern-day squid and cuttlefish. This genus is especially important in Jurassic stratigraphy, defining the Arnioceras semicostatum Biozone, a key interval used by geologists to correlate Sinemurian deposits across Europe. The presence of Arnioceras in the fossil record marks one of the earliest stages in the radiation of true ammonites following the end-Triassic extinction, making specimens like this both scientifically and historically significant.

The Black Ven Marls, part of the Charmouth Mudstone Formation, are world-renowned for producing exceptionally preserved fossils. These deposits were formed in a low-energy, shallow marine environment, where fine-grained clays and muds accumulated under oxygen-poor conditions. Such settings limited decomposition and scavenging, allowing delicate shells and skeletal remains to be buried intact. Over millions of years, mineral-rich waters permeated the sediment, turning these ancient sea beds into the fossil-rich marls that make Lyme Regis one of the most famous palaeontological sites in the world.

Morphology and Distinctive Features

The Arnioceras ammonite is characterised by its strongly ribbed, evolute shell, where all whorls are clearly visible. The ribs are sharp, radiating across the shell’s surface and terminating at a prominent keel along the venter (outer margin). This distinct morphology gave the ammonite a hydrodynamic shape, allowing it to glide efficiently through the Jurassic seas. The species’ broad whorls and open coiling pattern distinguish it from its contemporaries, making it a key fossil for identifying Sinemurian strata.

This specimen displays exceptional preservation, with the ribbing and suture lines clearly visible across the surface. The intricate shell patterns reveal how the ammonite’s internal chambers were structured, each one once filled with gas or liquid to help the animal maintain buoyancy. Its overall form suggests a free-swimming, predatory lifestyle, feeding on small crustaceans and other marine organisms. The robust shell and evenly spaced ribs also helped reinforce the structure against the pressure of deep-water environments.

Geological Age and Depositional Environment

This fossil dates to the Sinemurian Stage of the Lower Jurassic, approximately 197 million years ago, a period defined by stable marine ecosystems and the continued recovery of marine fauna after the end-Triassic extinction. During this era, southern England lay beneath a warm epicontinental sea that extended across much of Europe. The Black Ven Marls formed as fine mud and organic material settled slowly on the seafloor. The limited oxygen and calm conditions meant that fossils like this Arnioceras were preserved in remarkable three-dimensional detail.

The Jurassic Coast, now a UNESCO World Heritage Site, offers one of the world’s most continuous and complete geological records. The cliffs at Lyme Regis and Charmouth reveal nearly 185 million years of Earth’s history, and fossils from the Lower Lias—such as this Arnioceras—are among the most iconic from the region. These ammonites are not only valuable to science but also to collectors seeking authentic pieces of Britain’s prehistoric heritage.

Preparation and Provenance

This specimen was discovered and prepared entirely by our in-house team, ensuring authenticity, traceability, and expert craftsmanship. Alison’s careful preparation preserves every detail of the ammonite’s natural form, using gentle mechanical cleaning and consolidation techniques that maintain its integrity while enhancing its aesthetic appeal. Every fossil we sell is 100% genuine and comes with a Certificate of Authenticity, confirming its identification, provenance, and geological formation.

Our team’s hands-on approach—from discovery to final preparation—guarantees that each fossil is ethically sourced and professionally conserved. This Arnioceras specimen embodies the quality, scientific importance, and craftsmanship that define our collection.

Size and Presentation

Scale cube = 1 cm. Please refer to the photographs for complete sizing. The images show the exact specimen you will receive—not a stock image. The ammonite is beautifully displayed within its natural marl matrix, creating a striking contrast that enhances its ribbed detail and natural symmetry. Its robust form and fine preservation make it perfect for collectors, educational use, or as a decorative piece representing Dorset’s rich Jurassic heritage.

A Collector’s Fossil from the Heart of the Jurassic Coast

This Arnioceras Fossil Ammonite from Black Ven, Lyme Regis, represents a scientifically significant and visually impressive specimen from Britain’s most famous fossil site. Expertly prepared and authenticated, it offers a tangible connection to the Early Jurassic seas and stands as a timeless piece of natural history—an authentic fossil from the legendary Jurassic Coast of Dorset.

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Description

Authentic Arnioceras Fossil Ammonite from the Jurassic Coast, Dorset

This superb Arnioceras Fossil Ammonite originates from the Black Ven Marls of the Lower Lias Formation, part of the Jurassic Coast at Black Ven, Lyme Regis, Dorset, UK. Discovered by our own fossil collectors Alister and Alison on 05 November 2025, this genuine specimen has been expertly cleaned, prepped, and treated by Alison to reveal its intricate structure and natural beauty. Dating to approximately 195–200 million years ago, during the Early Jurassic (Sinemurian) Stage, this ammonite captures a fascinating moment in geological history when life was diversifying rapidly in the warm, shallow seas that once covered southern England.

Geological and Scientific Context

Arnioceras belongs to the family Arietitidae, within the superfamily Psiloceratoidea, and forms part of the order Ammonitida—an extinct group of cephalopods closely related to modern-day squid and cuttlefish. This genus is especially important in Jurassic stratigraphy, defining the Arnioceras semicostatum Biozone, a key interval used by geologists to correlate Sinemurian deposits across Europe. The presence of Arnioceras in the fossil record marks one of the earliest stages in the radiation of true ammonites following the end-Triassic extinction, making specimens like this both scientifically and historically significant.

The Black Ven Marls, part of the Charmouth Mudstone Formation, are world-renowned for producing exceptionally preserved fossils. These deposits were formed in a low-energy, shallow marine environment, where fine-grained clays and muds accumulated under oxygen-poor conditions. Such settings limited decomposition and scavenging, allowing delicate shells and skeletal remains to be buried intact. Over millions of years, mineral-rich waters permeated the sediment, turning these ancient sea beds into the fossil-rich marls that make Lyme Regis one of the most famous palaeontological sites in the world.

Morphology and Distinctive Features

The Arnioceras ammonite is characterised by its strongly ribbed, evolute shell, where all whorls are clearly visible. The ribs are sharp, radiating across the shell’s surface and terminating at a prominent keel along the venter (outer margin). This distinct morphology gave the ammonite a hydrodynamic shape, allowing it to glide efficiently through the Jurassic seas. The species’ broad whorls and open coiling pattern distinguish it from its contemporaries, making it a key fossil for identifying Sinemurian strata.

This specimen displays exceptional preservation, with the ribbing and suture lines clearly visible across the surface. The intricate shell patterns reveal how the ammonite’s internal chambers were structured, each one once filled with gas or liquid to help the animal maintain buoyancy. Its overall form suggests a free-swimming, predatory lifestyle, feeding on small crustaceans and other marine organisms. The robust shell and evenly spaced ribs also helped reinforce the structure against the pressure of deep-water environments.

Geological Age and Depositional Environment

This fossil dates to the Sinemurian Stage of the Lower Jurassic, approximately 197 million years ago, a period defined by stable marine ecosystems and the continued recovery of marine fauna after the end-Triassic extinction. During this era, southern England lay beneath a warm epicontinental sea that extended across much of Europe. The Black Ven Marls formed as fine mud and organic material settled slowly on the seafloor. The limited oxygen and calm conditions meant that fossils like this Arnioceras were preserved in remarkable three-dimensional detail.

The Jurassic Coast, now a UNESCO World Heritage Site, offers one of the world’s most continuous and complete geological records. The cliffs at Lyme Regis and Charmouth reveal nearly 185 million years of Earth’s history, and fossils from the Lower Lias—such as this Arnioceras—are among the most iconic from the region. These ammonites are not only valuable to science but also to collectors seeking authentic pieces of Britain’s prehistoric heritage.

Preparation and Provenance

This specimen was discovered and prepared entirely by our in-house team, ensuring authenticity, traceability, and expert craftsmanship. Alison’s careful preparation preserves every detail of the ammonite’s natural form, using gentle mechanical cleaning and consolidation techniques that maintain its integrity while enhancing its aesthetic appeal. Every fossil we sell is 100% genuine and comes with a Certificate of Authenticity, confirming its identification, provenance, and geological formation.

Our team’s hands-on approach—from discovery to final preparation—guarantees that each fossil is ethically sourced and professionally conserved. This Arnioceras specimen embodies the quality, scientific importance, and craftsmanship that define our collection.

Size and Presentation

Scale cube = 1 cm. Please refer to the photographs for complete sizing. The images show the exact specimen you will receive—not a stock image. The ammonite is beautifully displayed within its natural marl matrix, creating a striking contrast that enhances its ribbed detail and natural symmetry. Its robust form and fine preservation make it perfect for collectors, educational use, or as a decorative piece representing Dorset’s rich Jurassic heritage.

A Collector’s Fossil from the Heart of the Jurassic Coast

This Arnioceras Fossil Ammonite from Black Ven, Lyme Regis, represents a scientifically significant and visually impressive specimen from Britain’s most famous fossil site. Expertly prepared and authenticated, it offers a tangible connection to the Early Jurassic seas and stands as a timeless piece of natural history—an authentic fossil from the legendary Jurassic Coast of Dorset.

Additional information

Era

Jurassic
Origin

United Kingdom

Jurassic Information

The Jurassic Period (201–145 million years ago) was the golden age of dinosaurs, with iconic species like Brachiosaurus, Stegosaurus, and Allosaurus dominating the land. It was a time of warm, humid climates, with high sea levels that created vast shallow seas, supporting abundant marine reptiles, ammonites, and early coral reefs. The first birds, such as Archaeopteryx, evolved from small theropod dinosaurs, while early mammals remained small and nocturnal. Lush forests of cycads, conifers, and ferns covered the land, providing food for giant herbivores. The breakup of the supercontinent Pangaea accelerated, shaping Earth's geography and setting the stage for the diverse ecosystems of the Cretaceous.

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