Pentacrinites Crinoid Fossil Slab Jurassic Lyme Regis Dorset UK Specimen – Pentacrinites sp Black Ven Marls Lower Lias Crinoid

Description

Pentacrinites Crinoid Fossil Slab from the Jurassic Coast

This genuine Pentacrinites sp. crinoid fossil slab originates from the famous Black Ven Marls of the Lower Lias at Black Ven near Lyme Regis, Dorset, United Kingdom, part of the internationally recognised Jurassic Coast World Heritage Site. These fossils date to the Early Jurassic Period, approximately 201–183 million years ago, when warm shallow seas covered much of southern Britain.

Pentacrinites crinoids are among the most iconic fossils found along the Jurassic Coast. These marine echinoderms, often called sea lilies, lived attached to the seafloor by long flexible stems. Fossil slabs containing multiple crinoid stem segments or partial crowns provide striking visual displays and offer a direct glimpse into ancient marine ecosystems that thrived more than 190 million years ago.

This specimen preserves multiple crinoid elements embedded within the natural rock matrix, representing a classic fossil from one of Britain’s most celebrated fossil localities.

Geological Formation of the Black Ven Marls

The fossil originates from the Black Ven Marls, part of the Lower Lias Group, a sequence of marine sediments deposited during the earliest stages of the Jurassic Period. These deposits are extensively exposed along the cliffs and beaches around Lyme Regis and Charmouth.

The Black Ven Marls consist primarily of dark clay-rich marls and mudstones, which accumulated on the seabed of a relatively calm offshore marine basin. Fine sediment settled slowly through the water column, burying marine organisms and preserving them in exceptional detail.

This formation forms part of the broader Jurassic Coast stratigraphy, which records the transition from the Triassic into the Jurassic and preserves a remarkable diversity of fossils including ammonites, belemnites, bivalves, marine reptiles, fish, and echinoderms such as crinoids.

Classification and Biological Background

Pentacrinites belongs to the phylum Echinodermata, class Crinoidea, a group of marine animals related to modern starfish and sea urchins. Crinoids first appeared during the Ordovician Period and were extremely abundant throughout the Paleozoic and Mesozoic eras.

Within the crinoids, Pentacrinites is part of the order Isocrinida, a lineage of stalked crinoids that anchored themselves to the seafloor using a root-like holdfast.

The genus Pentacrinites was formally described by the English naturalist John Miller, who conducted pioneering work on fossil crinoids in the early nineteenth century.

These animals possessed a crown of feathery arms used to filter microscopic food particles from seawater. The arms captured plankton and organic debris, which were then transported to the mouth located at the center of the crown.

Morphology and Distinctive Features

Crinoid fossils such as Pentacrinites are often recognised by the distinctive structure of their stems and skeletal plates. The name Pentacrinites refers to the five-sided star-shaped cross section visible in many of the stem segments.

Characteristic features of Pentacrinites fossils may include:

• Circular or star-shaped stem segments known as columnals
• Articulated stem structure composed of stacked ossicles
• Occasional preserved arm fragments or crown elements
• Symmetrical pentaradial skeletal arrangement typical of echinoderms

When preserved in slabs, these stem segments can appear as chains or clusters across the rock surface, creating visually striking fossil patterns.

Early Jurassic Marine Ecosystem

During the Early Jurassic, the region around Lyme Regis was submerged beneath a shallow marine basin connected to the ancient Tethys Ocean. These waters supported diverse marine communities including ammonites, belemnites, fish, crustaceans, and numerous echinoderms.

Crinoids such as Pentacrinites lived attached to the seabed or anchored to firm substrates where they extended their arms into the water column to capture suspended food particles.

Occasionally, storms or underwater currents could break apart crinoid colonies, scattering stem segments across the seafloor. These remains were then buried by fine sediment and preserved as fossil slabs within the marl deposits.

Authentic Fossil Specimen

This fossil is a genuine Pentacrinites crinoid slab from the Black Ven Marls of the Lower Lias at Lyme Regis, Dorset, UK. The specimen has been carefully selected for quality and display appeal.

The photograph shows the actual fossil specimen you will receive, allowing collectors to clearly see the preserved crinoid stems within the natural matrix.

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.

Pentacrinites fossils from the Jurassic Coast are highly prized due to their connection with the rich marine ecosystems of the Early Jurassic and their distinctive star-shaped skeletal structure. A crinoid slab from Black Ven represents a classic fossil specimen and a beautiful addition to any fossil collection, geological display, or educational exhibit.