Plesiosaur Bone Fossil Reptile Black Ven Marls Lower Lias Jurassic Coast Black Ven Lyme Regis Dorset UK

Description

Authentic Plesiosaur Fossil Bone from the Jurassic Coast

This outstanding Plesiosaur Fossil Reptile Bone is a genuine specimen from the Black Ven Marls, Lower Lias Formation, collected along the world-renowned Jurassic Coast at Black Ven, Lyme Regis, Dorset, UK. Dating from the Early Jurassic Period (approximately 195–200 million years ago), this fossil represents the remains of a marine reptile that once ruled the ancient seas of what is now southern England.

Your specimen was discovered by our team members, Alister and Alison, on 15 September 2025, and has been carefully cleaned, prepped, and treated by Alison. The photograph shows the exact fossil you will receive, selected for its strong detail, preservation, and geological significance.

Geological Context and Origin

This specimen comes from the Black Ven Marls Member of the Charmouth Mudstone Formation, part of the Lower Lias Group, which forms the cliffs between Lyme Regis and Charmouth on the UNESCO World Heritage Jurassic Coast. These deposits were laid down during the Sinemurian Stage of the Early Jurassic in a shallow marine environment composed of fine-grained muds and silts. Over millions of years, these sediments accumulated in low-oxygen (anoxic) conditions, allowing the remains of marine reptiles, ammonites, and other organisms to be preserved in remarkable detail.

The Black Ven Marls are globally renowned for producing spectacular marine reptile fossils, including Ichthyosaurs, Plesiosaurs, and Pliosaurs, along with abundant invertebrates such as ammonites and belemnites. The unique sedimentary chemistry of this environment — rich in calcium carbonate, pyrite, and organic material — promoted mineral replacement, preserving the structure of bones in stone over geological time. This specimen likely comes from the Arnioceras semicostatum Biozone, a horizon well known to palaeontologists for yielding Early Jurassic vertebrate remains.

Scientific Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Reptilia
• Order: Plesiosauria
• Superfamily: Plesiosauroidea
• Family: Plesiosauridae (representative)
• Genus: Plesiosaurus (representative)
• Age: Early Jurassic (Sinemurian Stage)
• Formation: Black Ven Marls, Lower Lias
• Locality: Black Ven, Lyme Regis, Dorset, UK

Plesiosaurus was first described in 1821 by the geologist William Conybeare from specimens discovered in the very same region by pioneering fossil collector Mary Anning. The species became one of the first fully recognised examples of a prehistoric marine reptile, cementing Lyme Regis as a cornerstone of early palaeontology.

Morphological Features and Preservation

This Plesiosaur Fossil Bone displays the robust, dense structure characteristic of marine reptile skeletal elements. Depending on its morphology, it likely represents a limb or rib fragment, showing a combination of strength and curvature adapted for powerful aquatic propulsion. The bone surface retains natural texture and subtle growth line patterns, with fine mineralisation that accentuates the internal structure.

The fossil exhibits the classic grey to brown coloration typical of material from the Black Ven Marls, with occasional traces of pyrite mineralisation, adding a faint metallic sheen under light. This mineral replacement process has preserved the microstructure of the bone, providing insight into the anatomy of the Plesiosaur and the conditions of fossilisation. The scale cube (1 cm) shown in the image provides accurate size reference, and full sizing is available in the listing photos. The fossil has been professionally stabilised and treated, ensuring long-term preservation without compromising its natural integrity.

Palaeobiological and Scientific Significance

Plesiosaurs were remarkable marine reptiles that inhabited the Jurassic oceans, with long necks, broad bodies, and four strong paddle-like limbs that enabled them to glide through the water with elegant precision. They were apex predators, preying on fish, squid, and small marine reptiles. Their unique body design and bone density allowed for stability and buoyancy control while swimming in shallow seas.

This bone fragment is a direct link to that ancient world, illustrating the robust anatomy that supported these powerful swimmers. Each Plesiosaur bone helps scientists reconstruct the evolutionary history, locomotion, and ecology of these fascinating creatures. Fossils from Black Ven are particularly significant because they come from one of the most scientifically valuable and historically important fossil sites in the world — the very cliffs that sparked the birth of palaeontology in Britain.

The preservation of this specimen within the Black Ven Marls highlights the unique depositional conditions that captured moments of Jurassic life. Such fossils are not just scientific artefacts but pieces of deep time — tangible evidence of an ecosystem that existed nearly 200 million years ago.

Authenticity and Provenance

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity. Each piece is responsibly collected, professionally prepared, and ethically sourced to ensure quality and transparency. We never sell replicas or artificially enhanced fossils — the specimen shown in the photographs is the exact fossil you will receive.

This Plesiosaur Fossil Reptile Bone from Black Ven, Lyme Regis, Dorset, UK is a truly exceptional piece from the historic Jurassic Coast. It offers not only aesthetic appeal but also significant scientific and educational value — a real piece of Britain’s prehistoric past, preserved from the ancient seas of the Early Jurassic.