Description
Pentacrinites Crinoid Fossil Nodule – Jurassic Coast, Lyme Regis, Dorset
This genuine Pentacrinites crinoid fossil nodule is a beautifully preserved specimen from the famous Black Ven Marls of Charmouth, Lyme Regis, located along the UNESCO World Heritage Jurassic Coast in Dorset, UK. Dating to the Lower Lias of the Early Jurassic period, approximately 199–190 million years ago, this fossil offers a remarkable glimpse into ancient marine ecosystems.
Carefully selected for its natural preservation and display quality, this nodule contains fossilised crinoid remains protected within a calcareous concretion. The fossil shown in the photographs is the exact specimen you will receive and 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 England. These deposits are world-renowned for their exceptional fossil preservation, particularly of marine reptiles, ammonites, and echinoderms such as crinoids.
The sediments were laid down during the Sinemurian stage of the Early Jurassic. Fine-grained muds accumulated in a relatively low-energy environment, allowing delicate skeletal material to settle and be preserved. Periodic anoxic conditions on the seabed reduced decay and disturbance, enhancing fossil preservation.
The formation of nodules within these marls played a critical role in protecting fossils. Early mineral cementation around organic remains created concretions that shielded the fossils from compression and weathering over millions of years.
Fossil Identification – Pentacrinites (Class: Crinoidea, Order: Isocrinida)
Pentacrinites is a genus of crinoid, a group of marine echinoderms related to starfish and sea urchins. These organisms are commonly referred to as “sea lilies” due to their plant-like appearance, although they are fully marine animals.
Pentacrinites is characterised by its long, segmented stem composed of pentagonal columnals. These stems supported a crown of feathery arms used for filter feeding. The genus is typically placed within the family Pentacrinitidae and is a well-known component of Early Jurassic marine faunas.
Morphology and Notable Features
This fossil nodule preserves key features of Pentacrinites, often protected in three-dimensional form within the concretion:
- Distinct pentagonal stem segments (columnals)
- Articulated sections of crinoid stem preserved within the nodule
- Natural concretion matrix protecting fossil detail
- Subtle contrast between fossil material and surrounding sediment
- Potential clustering of elements indicating accumulation or colony structure
The pentagonal geometry of the columnals is a defining characteristic, giving Pentacrinites its name and making it easily recognisable among fossil crinoids.
Depositional Environment and Fossil Formation
During the Early Jurassic, the Lyme Regis region was submerged beneath a warm, shallow sea rich in marine life. Crinoids such as Pentacrinites either anchored themselves to the seabed or attached to floating debris, forming dense communities.
Following death or disarticulation, the skeletal elements settled onto the seabed. In certain conditions, early cementation of surrounding sediments formed nodules around the remains. These nodules provided a protective environment, preserving the fossil in greater detail than surrounding sediments alone.
Over time, mineralisation replaced the original calcite skeleton, preserving the structure within the nodule while maintaining its three-dimensional integrity.
Scientific and Collecting Significance
Pentacrinites fossils are highly valued for their distinctive morphology and their role in understanding Jurassic marine ecosystems. Specimens from the Jurassic Coast are particularly significant due to their well-documented geological context and historical importance.
Lyme Regis is one of the most important fossil localities in the world, with discoveries from this area contributing significantly to the development of palaeontology. Crinoid nodules are especially sought after by collectors, as they often preserve fossils in exceptional detail.
Authenticity and Presentation
This fossil is a 100% genuine Pentacrinites crinoid 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 images, allowing you to clearly assess the scale and detail of the specimen.
Ideal for Collectors, Display, or Educational Use
This Pentacrinites fossil nodule is an outstanding addition to any fossil collection, offering both scientific value and natural beauty. Ideal for collectors, educators, or as a unique display piece, it represents a genuine fragment of Jurassic marine life preserved within one of the most famous fossil-bearing formations in the world.
Reviews
There are no reviews yet.