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 Ammonite in Fossil Wood and Calcite Block Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen
Arnioceras Ammonite in Fossil Wood and Calcite Block Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen - Image 2
Arnioceras Ammonite in Fossil Wood and Calcite Block Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen - Image 3
Arnioceras Ammonite in Fossil Wood and Calcite Block Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen - Image 4

Arnioceras Ammonite in Fossil Wood and Calcite Block Jurassic Coast Lyme Regis Dorset UK – Genuine Black Ven Marls Lower Lias Specimen

£48.00

Authentic Arnioceras Ammonite in Fossil Wood and Calcite Block from the Jurassic Coast, Dorset

This remarkable Arnioceras Ammonite in Fossil Wood and Calcite Block originates from the world-famous Black Ven Marls of the Lower Lias Formation, part of the Jurassic Coast at Black Ven, Lyme Regis, Dorset, UK. Discovered by our own field collectors Alister and Alison on 05 November 2025, this unique specimen was carefully cleaned, prepped, and treated by Alison to bring out every natural detail. Dating from the Early Jurassic (Sinemurian) Stage, around 195–200 million years ago, this piece combines the elegance of an Arnioceras ammonite with the rare occurrence of fossil wood and calcite mineralisation—making it a highly distinctive and scientifically valuable specimen from one of the most famous fossil localities in the world.

Geological and Scientific Context

The genus Arnioceras belongs to the family Arietitidae, within the superfamily Psiloceratoidea and the order Ammonitida. It represents an important early ammonite lineage from the Sinemurian Stage of the Lower Jurassic, a period when new marine ecosystems flourished following the end-Triassic extinction. Arnioceras is significant for defining the Arnioceras semicostatum Biozone, which serves as a key biostratigraphic marker used by geologists to date early Jurassic sediments globally.

The Black Ven Marls, part of the Charmouth Mudstone Formation, were deposited in a low-energy, shallow marine environment where fine-grained muds and calcareous sediments settled on the sea floor. These calm, oxygen-depleted conditions provided ideal circumstances for exceptional fossil preservation. In this specimen, mineral-rich waters later permeated the sediment, replacing shell and organic material with calcite and preserving fragments of fossilised wood alongside the ammonite—an occurrence that captures a vivid snapshot of life and deposition during the Early Jurassic seas.

Morphology and Distinctive Features

The Arnioceras ammonite is renowned for its strongly ribbed, evolute shell, with all whorls visible from above. Its ribs are sharp, radiating from the inner coil to the venter (outer edge), giving the shell a bold, sculpted appearance. The shell shape is generally compressed with a rounded whorl section and pronounced keel, adaptations that likely enhanced hydrodynamics for swimming in open water.

This specimen displays exquisite preservation, with the ammonite beautifully embedded in a calcite-rich matrix that sparkles under light. The surrounding fossilised wood fragments provide a rare contextual association between marine and drifted terrestrial material—possibly remnants of ancient trees washed out to sea and buried in marine sediments. Such occurrences are uncommon, making this combination of Arnioceras, fossil wood, and calcite crystallisation particularly prized among collectors and researchers alike.

The contrast between the warm calcite tones and the dark fossil wood creates a visually striking composition, while the ammonite’s detailed ribbing and suture patterns stand out sharply against the polished matrix.

Geological Age and Formation

This specimen dates from the Sinemurian Stage of the Lower Lias, approximately 197 million years ago. The Black Ven Marls represent one of the richest fossil-bearing units in the British Isles and form a key part of the UNESCO World Heritage-listed Jurassic Coast. These marls consist of alternating layers of clay and limestone, deposited in a slowly subsiding sea basin during the early Jurassic period. The result was a unique environment that preserved a diverse array of marine life, including ammonites, bivalves, belemnites, and marine reptiles.

The combination of Arnioceras and fossilised wood within this block highlights the interplay between land and sea during this geological age—when rivers transported organic material from Jurassic forests into shallow marine basins, where it mingled with the shells of sea-dwelling organisms before fossilisation.

Preparation and Provenance

This fossil was discovered and prepared entirely by our in-house team, ensuring full traceability and expert craftsmanship. Alison’s precision cleaning and stabilisation techniques ensure the fossil remains in excellent condition while maintaining its natural authenticity. Every specimen we sell is 100% genuine and comes with a Certificate of Authenticity, confirming its species, age, and origin.

The careful preparation of this specimen enhances both its scientific and aesthetic value, revealing the ammonite’s detailed features, the texture of the fossil wood, and the natural crystallisation of the calcite matrix.

Size and Presentation

Scale cube = 1 cm. Please refer to the listing photographs for full sizing. The images show the exact specimen you will receive. The block is sturdy and stable, ideal for display in a collection, museum, or educational setting. The combination of ammonite shell, fossil wood, and calcite makes this an exceptional natural display piece that bridges geology, palaeontology, and mineralogy.

A Unique Collector’s Specimen from the Jurassic Coast

This Arnioceras Ammonite in Fossil Wood and Calcite Block is a rare and captivating specimen that embodies the beauty and scientific intrigue of Dorset’s Black Ven Marls. With its perfect balance of fossil preservation, mineralisation, and natural composition, it represents one of the finest examples of the Jurassic Coast’s heritage—a true collector’s piece from Britain’s most iconic fossil locality.

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Description

Authentic Arnioceras Ammonite in Fossil Wood and Calcite Block from the Jurassic Coast, Dorset

This remarkable Arnioceras Ammonite in Fossil Wood and Calcite Block originates from the world-famous Black Ven Marls of the Lower Lias Formation, part of the Jurassic Coast at Black Ven, Lyme Regis, Dorset, UK. Discovered by our own field collectors Alister and Alison on 05 November 2025, this unique specimen was carefully cleaned, prepped, and treated by Alison to bring out every natural detail. Dating from the Early Jurassic (Sinemurian) Stage, around 195–200 million years ago, this piece combines the elegance of an Arnioceras ammonite with the rare occurrence of fossil wood and calcite mineralisation—making it a highly distinctive and scientifically valuable specimen from one of the most famous fossil localities in the world.

Geological and Scientific Context

The genus Arnioceras belongs to the family Arietitidae, within the superfamily Psiloceratoidea and the order Ammonitida. It represents an important early ammonite lineage from the Sinemurian Stage of the Lower Jurassic, a period when new marine ecosystems flourished following the end-Triassic extinction. Arnioceras is significant for defining the Arnioceras semicostatum Biozone, which serves as a key biostratigraphic marker used by geologists to date early Jurassic sediments globally.

The Black Ven Marls, part of the Charmouth Mudstone Formation, were deposited in a low-energy, shallow marine environment where fine-grained muds and calcareous sediments settled on the sea floor. These calm, oxygen-depleted conditions provided ideal circumstances for exceptional fossil preservation. In this specimen, mineral-rich waters later permeated the sediment, replacing shell and organic material with calcite and preserving fragments of fossilised wood alongside the ammonite—an occurrence that captures a vivid snapshot of life and deposition during the Early Jurassic seas.

Morphology and Distinctive Features

The Arnioceras ammonite is renowned for its strongly ribbed, evolute shell, with all whorls visible from above. Its ribs are sharp, radiating from the inner coil to the venter (outer edge), giving the shell a bold, sculpted appearance. The shell shape is generally compressed with a rounded whorl section and pronounced keel, adaptations that likely enhanced hydrodynamics for swimming in open water.

This specimen displays exquisite preservation, with the ammonite beautifully embedded in a calcite-rich matrix that sparkles under light. The surrounding fossilised wood fragments provide a rare contextual association between marine and drifted terrestrial material—possibly remnants of ancient trees washed out to sea and buried in marine sediments. Such occurrences are uncommon, making this combination of Arnioceras, fossil wood, and calcite crystallisation particularly prized among collectors and researchers alike.

The contrast between the warm calcite tones and the dark fossil wood creates a visually striking composition, while the ammonite’s detailed ribbing and suture patterns stand out sharply against the polished matrix.

Geological Age and Formation

This specimen dates from the Sinemurian Stage of the Lower Lias, approximately 197 million years ago. The Black Ven Marls represent one of the richest fossil-bearing units in the British Isles and form a key part of the UNESCO World Heritage-listed Jurassic Coast. These marls consist of alternating layers of clay and limestone, deposited in a slowly subsiding sea basin during the early Jurassic period. The result was a unique environment that preserved a diverse array of marine life, including ammonites, bivalves, belemnites, and marine reptiles.

The combination of Arnioceras and fossilised wood within this block highlights the interplay between land and sea during this geological age—when rivers transported organic material from Jurassic forests into shallow marine basins, where it mingled with the shells of sea-dwelling organisms before fossilisation.

Preparation and Provenance

This fossil was discovered and prepared entirely by our in-house team, ensuring full traceability and expert craftsmanship. Alison’s precision cleaning and stabilisation techniques ensure the fossil remains in excellent condition while maintaining its natural authenticity. Every specimen we sell is 100% genuine and comes with a Certificate of Authenticity, confirming its species, age, and origin.

The careful preparation of this specimen enhances both its scientific and aesthetic value, revealing the ammonite’s detailed features, the texture of the fossil wood, and the natural crystallisation of the calcite matrix.

Size and Presentation

Scale cube = 1 cm. Please refer to the listing photographs for full sizing. The images show the exact specimen you will receive. The block is sturdy and stable, ideal for display in a collection, museum, or educational setting. The combination of ammonite shell, fossil wood, and calcite makes this an exceptional natural display piece that bridges geology, palaeontology, and mineralogy.

A Unique Collector’s Specimen from the Jurassic Coast

This Arnioceras Ammonite in Fossil Wood and Calcite Block is a rare and captivating specimen that embodies the beauty and scientific intrigue of Dorset’s Black Ven Marls. With its perfect balance of fossil preservation, mineralisation, and natural composition, it represents one of the finest examples of the Jurassic Coast’s heritage—a true collector’s piece from Britain’s most iconic fossil locality.

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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