4in Asteroceras Calcite Ammonite Fossil Positive and Negative Jurassic Coast Dorset UK Premium COA Included

Description

Genuine 4″ Asteroceras Calcite Ammonite – Positive and Negative Pair from Dorset

Offered here is an outstanding 4 inch Asteroceras calcite ammonite fossil, preserved as both a positive and negative split pair, from the famous Black Ven Marls of the Lower Lias Formation along the world-renowned Jurassic Coast of Dorset, England. This exceptional specimen comes from Stonebarrow Cliff, Charmouth, Lyme Regis, one of Europe’s most celebrated ammonite fossil localities.

A complete positive and negative ammonite pair is especially desirable, as it preserves both halves of the fossil split naturally through the rock, revealing the ammonite in complementary detail. At 4 inches, this is a large and impressive display piece with strong presence, excellent preservation, and outstanding visual appeal.

This is a carefully chosen specimen, selected for its bold ribbing, beautiful calcite mineralisation, and premium collector quality. The photographs show the exact fossil you will receive, with full sizing clearly visible in the provided images.

Every fossil we offer is a genuine specimen, and this ammonite includes a fully hand-signed Premium Certificate of Authenticity, providing lifetime assurance, provenance, and exceptional buyer confidence.

Geological Setting – Black Ven Marls, Lower Lias

This fossil originates from the famous Black Ven Marls, part of the Lower Lias Group, dating to the Early Jurassic approximately 190–200 million years ago. During this period, Dorset lay beneath a warm, shallow marine sea rich in ammonites, belemnites, fish, and large marine reptiles such as ichthyosaurs and plesiosaurs.

The Black Ven Marls were deposited in a quiet offshore environment where fine muds settled gently onto the seabed. Low oxygen conditions limited scavenging, allowing shells to be buried rapidly and fossilised in remarkable detail.

Stonebarrow Cliff and the Charmouth coastline are internationally famous for producing some of the finest Jurassic ammonites in the world, making fossils from this locality highly sought after.

Fossil Species – Asteroceras Ammonite

Asteroceras is a classic Lower Jurassic ammonite genus belonging to the extinct subclass Ammonoidea, within the class Cephalopoda. Ammonites were marine molluscs related to modern squid and cuttlefish and were among the most abundant predators of Jurassic seas.

Asteroceras is prized for its robust shell, strong ribbing, and powerful spiral form. These ammonites are also scientifically important, serving as index fossils that help geologists date and correlate Early Jurassic strata across Europe.

Specimens from Lyme Regis and Charmouth are especially collectible due to the worldwide reputation of the Dorset Jurassic Coast.

Positive and Negative Split Pair – Rare Display Feature

This specimen is preserved as a positive and negative split, meaning the ammonite is represented both as the raised fossil shell impression (positive) and as the matching mould impression (negative) in the counterpart rock.

These pairs are highly valued because they:

• Provide a complete fossil representation
• Reveal different aspects of shell detail
• Make a striking and educational display set
• Are rarer than single ammonite finds

This feature makes the fossil ideal for collectors and teaching displays, showing how ammonites are preserved within sedimentary rock.

Calcite Preservation and Visual Appeal

This ammonite displays beautiful calcite mineralisation, formed when mineral-rich fluids replaced or infilled the shell during fossilisation. Calcite preservation gives the fossil a bright, crystalline appearance that stands out strongly against the Jurassic matrix.

At 4 inches, this specimen offers excellent ribbing definition and a commanding presence, making it a standout centrepiece fossil.

Premium Authenticity and Collector Confidence

This is a 100% genuine Asteroceras calcite ammonite fossil split pair, responsibly sourced from Stonebarrow Cliff on the Dorset Jurassic Coast.

It includes a fully hand-signed Premium Certificate of Authenticity, ensuring lifetime confidence in provenance and genuineness.

Ideal For Collectors, Gifts and Museum Displays

This fossil is perfect for:

• Serious ammonite and Jurassic fossil collectors
• Split pair positive/negative fossil enthusiasts
• Lyme Regis and Charmouth Jurassic Coast fans
• Museum-quality natural history displays
• Unique prehistoric gifts with premium certification

A rare opportunity to own an authentic 4″ Asteroceras calcite ammonite positive and negative pair from the legendary Black Ven Marls of Dorset, preserved from an ancient sea nearly 200 million years ago and accompanied by a premium lifetime certificate.