Description
Genuine Sonninia corrugata Ammonite Fossil – Bajocian, Dorset
This genuine fossil ammonite is identified as Sonninia corrugata, a collectable Middle Jurassic ammonite from the Inferior Oolite Group at Penhard Lane, Sherborne, Dorset, UK. Dating to the Bajocian Stage of the Middle Jurassic, specifically the Sauzei Zone, this specimen represents ancient marine life from approximately 170 million years ago, when the area now known as Dorset lay beneath warm, shallow Jurassic seas.
This fossil is a carefully chosen specimen, with the photograph showing the actual fossil you will receive. Full sizing can be seen in the photo. It is supplied as a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card, making it an excellent piece for fossil collectors, educational collections, natural history displays, and anyone interested in British Jurassic ammonites.
Fossil Type and Species
Ammonites were extinct marine cephalopods related to modern squid, cuttlefish, octopus, and nautilus. They lived inside coiled, chambered shells, with the animal occupying the final body chamber while earlier chambers helped regulate buoyancy in the water column. Their rapid evolution and wide distribution make ammonites some of the most useful fossils for dating and correlating Jurassic rock layers.
Sonninia corrugata belongs to the ammonite genus Sonninia, a well-known Bajocian ammonite group associated with early Middle Jurassic marine deposits. Sonninia ammonites are commonly placed within the family Sonniniidae, superfamily Hammatoceratoidea, and order Ammonitida. They are highly regarded by collectors because of their distinctive ribbed shell forms, scientific importance, and strong connection with the Inferior Oolite successions of Dorset and Somerset.
The species name corrugata reflects the strongly textured, ribbed character associated with the shell ornamentation. Sonninia ammonites often display moderately evolute coiling, meaning the inner whorls can remain visible rather than being completely covered by later shell growth. Many examples show bold ribs across the flanks, sometimes with a slightly irregular or corrugated appearance, giving the shell a striking Jurassic look. Depending on preservation and growth stage, the whorl section may appear compressed to moderately inflated, with ornamentation that changes as the animal matured.
Sauzei Zone and Geological Importance
This specimen is from the Sauzei Zone, an important ammonite biozone within the Bajocian Stage of the Middle Jurassic. Ammonite biozones are widely used in geology because ammonites evolved rapidly and spread across broad marine areas. Their changing shell forms allow geologists to compare and date rock layers from different localities with considerable precision.
A fossil associated with the Sauzei Zone has added scientific and collecting value because it places the specimen within a more specific part of the Jurassic timescale. The Sauzei Zone is particularly important in early Bajocian ammonite studies and includes faunas that help document the development of Middle Jurassic ammonite lineages. Sonninia species are characteristic fossils in these successions, making this specimen a strong representative of its geological interval.
Inferior Oolite Group, Sherborne, Dorset
The Inferior Oolite Group is one of Britain’s best-known Middle Jurassic fossil-bearing rock units. Despite the name “Inferior”, the word refers to its position below the Great Oolite in the geological sequence, not to the quality of the fossils. These rocks are famous for producing ammonites, brachiopods, bivalves, gastropods, echinoids, corals, and other marine fossils.
At Penhard Lane, Sherborne, the Inferior Oolite succession records a shallow marine carbonate environment from the Bajocian. During this period, Dorset formed part of a warm Jurassic shelf sea. Lime-rich sediments, shell debris, oolitic grains, and marine muds accumulated on the sea floor, later compacting into limestone and related sedimentary rocks. These conditions created an excellent setting for the preservation of ammonites and other marine invertebrates.
The ancient sea would have supported a diverse ecosystem of swimming cephalopods, seabed-dwelling invertebrates, and other marine organisms. Ammonites such as Sonninia moved through this marine environment as active animals, eventually becoming part of the fossil record after burial in Jurassic sediment.
Collectable British Jurassic Ammonite
This Sonninia corrugata ammonite fossil is a desirable specimen for collectors because it combines a named ammonite species, a classic British locality, a precise Bajocian biozone, and genuine Jurassic age. Fossils from Sherborne and the wider Dorset region are especially valued because of their long association with British palaeontology and their place within the famous Jurassic successions of southern England.
The combination of Sonninia corrugata, Sauzei Zone, Inferior Oolite Group, and Penhard Lane, Sherborne gives this fossil strong display and labelling appeal. It is suitable for a fossil cabinet, educational geology collection, natural history display, or specialist ammonite collection focused on British Jurassic material.
Authenticity and Presentation
This fossil is a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. The specimen has been carefully selected, and the photograph shows the actual fossil you will receive. Full sizing can be seen in the photo.
As a genuine Sonninia corrugata ammonite from Penhard Lane, Sherborne, Dorset, this fossil offers an attractive and scientifically interesting example of Middle Jurassic marine life from the Inferior Oolite Group, with strong collecting appeal for anyone interested in British fossils, ammonites, and natural history specimens.
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