Description Available for purchase is a Rare 7″ Fossil Ammonite of Coroniceras rotiforme from the Lower Sinemurian Stage of the Lower Jurassic, found in Keynsham, Bristol, Somerset, United Kingdom — a classic and historically significant fossil location in the UK. Scale Rule Squares / Cube = 1cm — please refer to the photograph for full sizing. The fossil shown is the actual specimen you will receive, professionally selected for its scientific integrity and aesthetic quality. Key Geological and Scientific Details: Species: Coroniceras rotiforme Fossil Type: Ammonite (extinct marine cephalopod) Geological Period: Jurassic Stage: Lower Sinemurian (Early Jurassic) Biozone: Arietes Ammonite Zone, specifically within the Bucklandi Subzone Location: Keynsham, Bristol, Somerset, England, UK Approximate Age: ~199 million years Stratigraphy: Lower Lias Formation (Blue Lias Group) Order: Ammonitida Superfamily: Psiloceratoidea Family: Arietitidae Described By: Originally described under various synonyms; final taxonomy attributed to 19th-century palaeontologists refining the genus Coroniceras Morphology Features: Coroniceras rotiforme is known for its planispiral, evolute shell with compressed whorls and a strongly ridged and ribbed ornamentation that often terminates in tubercles or spines along the venter. The suture lines are moderately complex, and the shell surface typically shows robust primary ribs and fine secondary ones. This specimen displays remarkable preservation, making it ideal for both collectors and educational display. Depositional Environment: This ammonite comes from the Lower Lias Formation, a classic marine sedimentary unit comprising limestone and shale layers. The environment of deposition was a shallow epicontinental sea, low in energy, conducive to the exceptional fossilisation of marine fauna — especially ammonites, bivalves, and marine reptiles. Notable Context: The Coroniceras genus is well-represented in Lower Jurassic ammonite faunas, with rotiforme being one of the larger and more visually impressive species. Its occurrence in the Bucklandi Zone helps refine the stratigraphic framework used across Britain and Europe, especially for correlating marine deposits. Authenticity Guarantee: All of our fossils are 100% genuine specimens, responsibly sourced and professionally handled. Every fossil comes with a Certificate of Authenticity, ensuring scientific integrity and buyer confidence. This Coroniceras rotiforme fossil is a highly desirable collector’s item — scientifically valuable, visually impressive, and steeped in palaeontological significance. Perfect for fossil enthusiasts, educational settings, or as a standout natural history display.
