Description
Sonninia (Fissilobiceras) sp. Ammonite Fossil – Inferior Oolite Group, Middle Jurassic, Dorset
This genuine Sonninia (Fissilobiceras) sp. ammonite fossil is a collectable Middle Jurassic marine cephalopod specimen from the Inferior Oolite Group at Red Hole Lane, Sherborne, Dorset, UK. Dating from the Bajocian Stage of the Middle Jurassic, specifically the Laeviuscula Subzone, this fossil is approximately 170 million years old and represents an ammonite from the warm shallow seas that once covered southern Britain.
This fossil is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. It has been carefully chosen as an individual fossil specimen, with a photo that shows the actual piece you will receive. Full sizing please see photo.
Geology and Geological Age
Sonninia (Fissilobiceras) sp. comes from the Inferior Oolite Group, one of the classic Middle Jurassic fossil-bearing units of southern England. The Inferior Oolite is famous for its oolitic limestones, carbonate-rich beds, shelly sediments and important ammonite faunas. These rocks were deposited during the Bajocian Stage, when Britain lay much closer to the equator than today and was covered by warm, shallow, tropical to subtropical seas.
The term “oolite” refers to small rounded carbonate grains known as ooids. These formed in shallow, agitated marine water and later accumulated with shell fragments, carbonate mud and the remains of marine organisms. Over time, these sediments became limestone and preserved a rich fossil record including ammonites, belemnites, bivalves, brachiopods, gastropods, echinoids, corals and other marine invertebrates.
Fossil Type and Species
This specimen is identified as Sonninia (Fissilobiceras) sp., meaning it belongs to the genus Sonninia and is associated with the subgenus Fissilobiceras, but is not assigned to a single named species. The “sp.” label is commonly used in palaeontology when a fossil can be confidently placed within a genus or subgenus, while the precise species is left open due to preservation, growth stage or the diagnostic features visible on the specimen.
Sonninia is a recognised Middle Jurassic ammonite genus within the order Ammonitida and is generally placed within the family Sonniniidae. Ammonites were extinct marine cephalopods related to modern squid, octopus and cuttlefish. Unlike their living relatives, ammonites possessed an external coiled shell divided internally into chambers. The living animal occupied the outer body chamber, while the earlier chambers helped regulate buoyancy.
Laeviuscula Subzone Stratigraphic Interest
This fossil is from the Bajocian Laeviuscula Subzone, an important ammonite subzone within the Middle Jurassic succession. Ammonite zones and subzones are especially valuable in geology because ammonites evolved rapidly and developed distinctive shell forms over relatively short intervals of geological time. This makes them excellent index fossils for dating and correlating marine rock layers.
A specimen with a recorded formation, locality and subzone carries stronger geological value than a fossil labelled only as Jurassic. The Laeviuscula Subzone places this ammonite within a well-recognised part of the Bajocian succession, making it particularly appealing for collectors of British Jurassic fossils, Dorset ammonites, Inferior Oolite specimens and carefully labelled stratigraphic material.
Morphology and Collectable Features
Sonninia (Fissilobiceras) ammonites are admired for their classic Jurassic ammonite appearance and attractive natural shell form. Depending on preservation and growth stage, this specimen may show visible whorls, ribbing, shell curvature, chamber structure, natural matrix contact, mineral replacement or sutural detail. These features give the fossil both visual appeal and scientific interest.
The ribbing and ornament on ammonite shells formed part of the original shell structure and may have helped strengthen the shell. Such features are also important for identification, as ammonite specialists compare whorl shape, rib style, ornament, venter form and suture patterns when studying related forms. In well-preserved examples, suture lines may appear as intricate patterns marking where the internal chamber walls met the outer shell.
Red Hole Lane, Sherborne Fossil Locality
Red Hole Lane, Sherborne, Dorset, is associated with fossil-bearing Middle Jurassic strata and is a notable locality for collectors interested in the Inferior Oolite Group. Dorset is internationally recognised for its Jurassic geology, and specimens from named localities such as Sherborne are especially desirable because they provide clear provenance and geological context.
This Sonninia (Fissilobiceras) sp. ammonite is suitable for fossil collectors, geology enthusiasts, educational collections, natural history displays, cabinet display and study collections focused on British fossils, Middle Jurassic ammonites and classic Dorset material.
Depositional Environment
This ammonite was preserved in sediments laid down beneath a warm Bajocian sea. The environment likely included shallow carbonate waters, oolitic shoals, shell banks and areas of marine sediment accumulation. After the ammonite died, its shell settled onto the sea floor and became buried among carbonate grains, shell debris and fine marine material.
Over millions of years, burial, compaction and mineral-rich groundwater transformed the remains into a fossil. The resulting specimen is a natural record of marine life from Middle Jurassic Dorset, when ammonites were abundant, diverse and highly important members of the Jurassic seas.
Authenticity and Display
This is a genuine Sonninia (Fissilobiceras) sp. ammonite fossil from the Inferior Oolite Group, Middle Jurassic, Bajocian, Laeviuscula Subzone of Red Hole Lane, Sherborne, Dorset, UK. It includes a Certificate of Authenticity lifetime guarantee generic card and is suitable for fossil collectors, geology enthusiasts, educational displays, natural history collections or as a distinctive gift for anyone interested in prehistoric marine life.
The fossil has been carefully selected, and the photo shows the actual specimen you will receive. Full sizing please see photo.
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