Microderoceras Cymbites Ammonite Fossil Block Lyme Regis Jurassic UK Lower Lias Black Ven Marls Multi Ammonite Specimen Authentic

Description

Microderoceras and Cymbites Ammonite Fossil Block – Jurassic Coast, UK

This superb ammonite fossil block features multiple specimens of Microderoceras and Cymbites preserved together within their original matrix, sourced from the renowned Black Ven Marls of Charmouth, Lyme Regis, on the iconic Jurassic Coast of Dorset, UK. Dating to the Lower Lias of the Early Jurassic period, approximately 199–190 million years ago, this piece captures a natural assemblage of ancient marine life in exceptional detail.

Carefully selected for its visual appeal and scientific value, this fossil block displays multiple ammonites in situ, offering a highly desirable and authentic representation of a Jurassic seabed snapshot. The exact specimen shown in the photographs is the one you will receive, and it includes a Certificate of Authenticity lifetime guarantee generic card.

Geological Context – Black Ven Marls, Lower Lias Formation

The Black Ven Marls are part of the Lower Jurassic Lias Group, a sequence of clay-rich marine sediments deposited in a shallow epicontinental sea that once covered much of southern Britain. These fine-grained sediments are famous for preserving delicate fossils with remarkable clarity.

The fossil horizon is typically associated with the Sinemurian stage of the Early Jurassic, a time of rapid ammonite evolution and diversification. The marls were deposited in a relatively low-energy environment, allowing fine sediment to settle and gently bury organic remains. Periodic low-oxygen conditions at the seabed reduced decay and scavenging, contributing to the exceptional preservation seen in ammonite-rich blocks such as this.

Fossil Identification – Microderoceras and Cymbites (Order: Ammonitida)

This fossil block contains multiple ammonites belonging to the genera Microderoceras and Cymbites, both part of the extinct Ammonitida order of marine cephalopods.

Microderoceras is recognised for its tightly coiled shell with fine ribbing and elegant whorl structure. It is typically associated with early Jurassic faunas and is often linked to the family Eoderoceratidae within the superfamily Eoderoceratoidea.

Cymbites, while less commonly referenced, represents another form of early ammonite displaying distinct shell morphology, often with smoother whorls or differing rib patterns. The presence of multiple genera within a single block highlights the biodiversity of the Early Jurassic seas.

Morphology and Notable Features

This natural fossil block showcases a clustered assemblage of ammonites preserved within their original sedimentary matrix, providing both scientific and aesthetic interest.

Key features include:

• Multiple ammonites preserved in situ within a single block
• Distinct coiling and ribbing patterns characteristic of Microderoceras
• Variation in size and morphology between specimens, indicating different growth stages or species
• Natural marine matrix from the Black Ven Marls
• Excellent preservation with clear fossil outlines and structural detail

The grouping of ammonites suggests either a natural accumulation on the seabed or rapid burial of multiple individuals, offering insight into the palaeoenvironment and potential depositional events.

Depositional Environment and Fossil Formation

During the Early Jurassic, the region around Lyme Regis was submerged beneath a warm, shallow sea rich in marine life. Ammonites were abundant and played a key role in the marine food chain.

Following death, their shells settled onto the seabed where they were gradually buried by fine sediment. In some cases, multiple shells accumulated together, either through gentle currents or mass mortality events. Rapid burial and low oxygen conditions prevented significant decomposition, allowing the shells to fossilise within the marl matrix.

Over millions of years, compaction and mineralisation preserved these fossils in remarkable detail, resulting in multi-specimen blocks such as this.

Historical and Collecting Significance

Charmouth and Lyme Regis are globally recognised as some of the most important fossil sites, with a rich history of discoveries that helped shape modern palaeontology. The area is closely associated with early fossil collectors such as Mary Anning, whose work brought marine reptiles and ammonites to scientific prominence.

Multi-ammonite blocks from this locality are especially prized by collectors, as they represent a more complete and natural snapshot of Jurassic marine life compared to single specimens.

Authenticity and Presentation

This fossil is a 100% genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. The fossil shown in the photographs is the exact piece you will receive.

Full sizing can be confirmed via the listing photographs, ensuring clarity on the scale and presence of the specimen.

Ideal for Collectors, Display, or Study

This Microderoceras and Cymbites ammonite fossil block is an outstanding addition to any fossil collection, offering both visual impact and scientific significance. Its natural composition, multiple specimens, and iconic Jurassic Coast origin make it perfect for collectors, educational use, or as a unique and meaningful display piece.