Description
This authentic fossil specimen is a beautifully preserved example of Dactylioceras (Orthodactylites) tenuicostatum, an iconic ammonite species from the Upper Lias deposits of the Lower Jurassic period (~183–189 million years ago). This fossil was found at the famous Runswick Bay, near Whitby, North Yorkshire—one of the UK’s most prolific Jurassic fossil sites.
Dactylioceras ammonites, especially those of the tenuicostatum variety, are known for their thin, regular ribbing and relatively flat, tightly coiled shells. Belonging to the subgenus Orthodactylites, this species is highly valued by collectors due to its excellent preservation, stratigraphic significance, and aesthetic appeal.
Geologically, this specimen comes from the Whitby Mudstone Formation, a deep marine shale deposit within the Upper Lias. These dark grey to black rocks were formed in an oxygen-depleted seabed, which contributed to the exceptional fossil preservation found throughout the area, especially for ammonites, belemnites, marine reptiles, and other invertebrates.
This particular specimen was part of the Alice Purnell Collection, a distinguished archive of carefully documented and professionally curated British fossils. It has been meticulously cleaned and prepared to reveal fine details of the shell structure, showcasing both scientific and natural beauty.
Item Details:
- Species: Dactylioceras (Orthodactylites) tenuicostatum
- Type: Fossil Ammonite
- Age: Lower Jurassic (Toarcian Stage)
- Stratigraphy: Upper Lias – Whitby Mudstone Formation
- Location: Runswick Bay, Whitby, North Yorkshire, UK
- Collection: Alice Purnell Collection
- Condition: Professionally cleaned and prepped
- Scale Reference: See image with 1cm scale cube
- Certificate of Authenticity: Included with every specimen
ACTUAL AS SEEN:
The image provided shows the exact fossil you will receive. This specimen has been individually selected and photographed to ensure accuracy. Please note that slight colour variations may occur due to lighting conditions and monitor settings. Once this specific item is sold, the listing will be updated with a new specimen and accompanying images.
100% Genuine British Fossil – Professionally Prepared – Certificate of Authenticity Included – Sourced from the Historic Jurassic Coast of Yorkshire
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