Rare Pachystropheus Fossil Bone Aust Cliff Triassic UK Specimen – Lissodus Associated Fossil Westbury Formation Rhaetian Gloucestershire

Description

Rare Pachystropheus or Lissodus Fossil Bone from Aust Cliff

This genuine Pachystropheus / Lissodus fossil bone originates from the renowned Westbury Formation exposures at Aust Cliff, Gloucestershire, United Kingdom. The fossil dates to the Late Triassic Period, Rhaetian Stage, approximately 208–201 million years ago, representing one of the final marine ecosystems that existed just before the mass extinction event marking the end of the Triassic

Aust Cliff is one of the most famous fossil localities in Britain for Late Triassic vertebrate remains. The site has produced a diverse assemblage of marine fossils including fish, sharks, marine reptiles, and early crocodile relatives. Fossils attributed to Pachystropheus, an unusual marine reptile, as well as Lissodus, a genus of hybodont shark, are among the notable discoveries from this formation.

This specimen represents a rare fragment of fossilised vertebrate bone from this important geological horizon and offers a direct connection to the prehistoric marine fauna inhabiting the ancient seas of the Late Triassic.

Geological Formation and Stratigraphic Context

The fossil was recovered from the Westbury Formation, a sedimentary unit within the Penarth Group that is widely exposed at Aust Cliff along the banks of the River Severn. These sediments were deposited during the Rhaetian Stage of the Late Triassic, a period immediately preceding the transition into the Jurassic Period.

The Westbury Formation consists primarily of dark grey to black shales and thin limestone layers, representing sediment accumulation within a shallow marine basin. These sediments contain concentrations of vertebrate remains often referred to as bone beds, where currents and storm activity concentrated skeletal material from marine organisms.

The famous Rhaetian Bone Bed at Aust Cliff is one of the most productive fossil horizons in Britain for Late Triassic vertebrate fossils. It contains abundant remains of sharks, bony fish, marine reptiles, and other marine animals.

Pachystropheus Marine Reptile

Pachystropheus is an unusual marine reptile known primarily from vertebrae and skeletal fragments found in Rhaetian deposits across Europe. It is generally considered a member of the order Thalattosauria, a group of marine reptiles adapted to coastal marine environments during the Triassic.

These reptiles were likely elongated aquatic predators, possessing streamlined bodies and strong tails suited to swimming in shallow marine environments. Fossil remains of Pachystropheus were first formally described by Sir Richard Owen, the British paleontologist famous for coining the term Dinosauria.

Lissodus Hybodont Shark

Lissodus represents a genus of hybodont sharks, belonging to the order Hybodontiformes, an extinct lineage of sharks that thrived throughout much of the Mesozoic Era. Hybodont sharks were highly adaptable predators inhabiting both marine and freshwater environments.

These sharks possessed distinctive teeth adapted for crushing and grinding prey such as shellfish and small marine organisms. Fossil remains from Aust Cliff include teeth, fin spines, and skeletal fragments associated with these ancient sharks.

The coexistence of Pachystropheus reptiles and Lissodus sharks within the same fossil deposits reflects the diversity of predators present in Late Triassic marine ecosystems.

Fossil Bone Preservation and Features

Fossil bones from the Aust Cliff bone beds are often preserved within phosphatic or mineralised sediments, giving them a distinctive dark coloration and dense fossilised texture.

Typical features of these fossils may include:

• Dense mineralised bone structure
• Dark coloration from phosphatic preservation
• Surface texture reflecting original bone structure
• Fragmentary form typical of bone bed deposits

These characteristics result from the fossilisation process within marine sediments where skeletal remains became mineralised over millions of years.

Late Triassic Marine Environment

During the Rhaetian Stage, much of Britain lay beneath shallow coastal seas connected to the Tethys Ocean. These waters supported a rich marine ecosystem populated by sharks, bony fish, marine reptiles, and invertebrates.

Periodic storms and currents concentrated skeletal remains into the bone beds now preserved within the Westbury Formation. These deposits provide an important window into marine life during the final stage of the Triassic, just before the extinction event that reshaped global ecosystems at the start of the Jurassic.

The fossil record from Aust Cliff is particularly significant because it preserves organisms living during this crucial transitional period in Earth’s history.

Authentic Fossil Specimen

This fossil is a genuine Pachystropheus or Lissodus bone fragment from the Westbury Formation at Aust Cliff, Gloucestershire, UK. The specimen has been carefully selected for quality and display appeal.

The photographs show the actual fossil specimen you will receive, ensuring authenticity and transparency for collectors.

Full sizing please see photo.

Certificate of Authenticity

This fossil includes a Certificate of Authenticity lifetime guarantee generic card, confirming that the specimen is a genuine natural fossil.

Fossils from the Aust Cliff Rhaetian bone beds are highly prized by collectors due to their rarity, geological importance, and connection to one of the final marine ecosystems of the Triassic Period. This specimen represents a fascinating piece of prehistoric marine history and a distinctive addition to any fossil collection or geological display.