Description
Hemicidaris Regular Echinoid Fossil – Cretaceous Period, Swanage, Dorset, England
This beautifully preserved echinoid fossil belongs to the genus Hemicidaris, a type of regular sea urchin that lived during the Cretaceous Period, over 100 million years ago. Discovered in the well-known fossil beds of Swanage, Dorset, on England’s Jurassic Coast, this specimen offers classic morphology and a glimpse into the ancient marine ecosystems of southern Britain.
Fossil Type & Species:
- Type: Invertebrate Fossil (Regular Echinoid / Sea Urchin)
- Genus: Hemicidaris
- Phylum: Echinodermata
- Class: Echinoidea
- Order: Cidaroida
- Superfamily: Cidaritoidea
- Family: Hemicidaridae
- Described by: Agassiz, mid-19th century (genus authority)
Geological & Stratigraphic Details:
- Location: Swanage, Dorset, England
- Formation: Cretaceous marine limestones and marls
- Geological Stage: Likely Early Cretaceous (exact substage unconfirmed)
- Age: ~145–100 million years ago
- Depositional Environment: Shallow warm seas with calcareous sedimentation ideal for echinoderm fossilisation
- Biozone: Cretaceous echinoid-bearing zones of southern England (specific zone unassigned)
Morphology & Features: This Hemicidaris fossil exhibits:
- Spherical to low domed test with distinct radial symmetry
- Primary tubercles arranged in orderly rows for spine attachment
- Visible ambulacral zones and interambulacral plates with granulation
- Robust test preservation, occasionally with partial spines or root bases intact
- Subtle colour variations from pale grey to chalky white or light brown
Notable: Hemicidaris is among the best-known genera of Cretaceous echinoids and is commonly used in palaeobiological studies and museum exhibits. Fossils from Swanage are particularly sought after due to their completeness and provenance from the iconic Jurassic Coast.
Specimen Details:
- Origin: Swanage, Dorset, England
- Genus: Hemicidaris (species undetermined)
- Fossil Type: Regular Echinoid / Sea Urchin Test
- Geological Stage: Early Cretaceous
- Size Reference: Scale rule square = 1cm (please see listing photo for sizing)
- Note: The specimen shown is the exact item you will receive
Authenticity & Quality: This is a 100% genuine fossil selected for its preservation quality. It comes with a Certificate of Authenticity. No reconstructions or enhancements have been applied.
Why Choose This Fossil? Ideal for:
- Echinoid and invertebrate fossil collectors
- British fossil enthusiasts
- Educational and museum displays
- Decorative geological specimens with scientific value
Shipping & Packaging: Shipped securely with eco-conscious packaging and full tracking. Every fossil is packed with care to ensure safe delivery.
Add a classic British sea urchin fossil to your collection with this authentic Hemicidaris echinoid from Swanage, Dorset.
All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.
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