Description
Rare Orbitremites derbiensis Crinoid Fossil from the Jurassic of Oxfordshire
This rare and highly collectible fossil specimen of Orbitremites derbiensis is a beautifully preserved crinoid from the famous Ardley Quarry in Ardley, Oxfordshire, United Kingdom. The fossil originates from the Ardley Member of the White Limestone Formation, dating to the Middle Jurassic period during the Bathonian stage, approximately 166–168 million years ago.
Crinoids are among the most elegant and recognisable marine fossils, belonging to the echinoderm group that also includes starfish and sea urchins. Often referred to as “sea lilies”, these organisms lived attached to the seabed and filtered nutrients from the surrounding seawater using delicate feather-like arms.
The fossil shown in the photographs is the exact specimen you will receive. Each piece is carefully selected for quality and authenticity and includes a Certificate of Authenticity lifetime guarantee card, confirming that the fossil is a genuine natural specimen.
Please refer to the photographs for the exact dimensions and scale of the fossil.
Geological Origin – Ardley Member, White Limestone Formation
This crinoid fossil originates from the Ardley Member of the White Limestone Formation, a well-known fossil-bearing geological unit in southern England. Ardley Quarry has produced an exceptional range of Middle Jurassic fossils and is widely studied by palaeontologists.
During the Bathonian stage of the Middle Jurassic, much of what is now the United Kingdom was covered by warm, shallow seas located in subtropical latitudes. These marine environments supported diverse communities of organisms including ammonites, bivalves, brachiopods, echinoderms, crustaceans, fish, and marine reptiles.
The White Limestone Formation consists primarily of pale micritic limestones deposited in shallow marine lagoonal and shelf environments. Calm water conditions and fine carbonate sediment allowed delicate marine organisms to be buried rapidly and preserved within the limestone.
These depositional conditions are responsible for the remarkable preservation of many fossils from Ardley Quarry, including rare echinoderms such as Orbitremites derbiensis.
About the Crinoid Species Orbitremites derbiensis
Orbitremites derbiensis is a species of crinoid belonging to the Class Crinoidea, within the Order Cyrtocrinida. Members of this group are characterised by their compact bodies and specialised attachment structures that allowed them to anchor to hard substrates on the sea floor.
Crinoids such as Orbitremites possessed a cup-shaped body known as the calyx, composed of interlocking calcite plates. From this central structure extended numerous feather-like arms used to capture microscopic food particles suspended in seawater.
Key morphological characteristics of Orbitremites derbiensis include:
- A distinctive circular to slightly domed calyx formed from articulated skeletal plates
- Radial plate arrangements typical of Jurassic crinoids
- Attachment structures that anchored the organism to the seabed or hard surfaces
- Adaptations for efficient suspension feeding within calm marine environments
The calcitic skeleton of crinoids fossilises well, and specimens such as this provide important insight into Jurassic echinoderm diversity.
Life in the Jurassic Marine Ecosystem
During the Middle Jurassic, crinoids formed an important component of marine benthic ecosystems. They lived attached to the seabed or other hard surfaces, extending their arms into the water column to filter plankton and organic particles from passing currents.
The shallow seas represented by the White Limestone Formation supported complex marine communities that included reef-like habitats, shell beds, and carbonate platforms. Crinoids occupied elevated positions above the seafloor, allowing them to maximise feeding efficiency in gentle marine currents.
Fossils such as Orbitremites derbiensis provide valuable evidence of the ecological structure of Jurassic marine environments and help scientists reconstruct ancient ecosystems that existed nearly 170 million years ago.
Collector and Display Information
- Species: Orbitremites derbiensis
- Fossil Type: Crinoid (Echinoderm)
- Geological Age: Middle Jurassic, Bathonian Stage
- Formation: White Limestone Formation
- Member: Ardley Member
- Locality: Ardley Quarry, Ardley, Oxfordshire, United Kingdom
- Preservation: Natural fossil preserved in limestone matrix
- Authenticity: 100% genuine fossil specimen
- Documentation: Includes Certificate of Authenticity lifetime guarantee card
This rare crinoid fossil from a classic Jurassic locality represents an outstanding collector’s specimen. Fossils from Ardley Quarry are highly sought after due to their scientific significance and the quality of preservation.
A superb addition to any fossil collection, natural history display, geological collection, or educational set, this specimen provides a direct connection to the rich marine life that flourished in the Jurassic seas of ancient Britain.
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