Description
Genuine Sonninia propinquans Ammonite Fossil – Lower Bajocian, Dorset
This genuine fossil ammonite is identified as Sonninia propinquans, a classic Middle Jurassic ammonite from the Inferior Oolite Group at Oborne Wood, Dorset, UK. Dating to the Lower Bajocian Stage of the Middle Jurassic, this specimen is approximately 170 million years old and represents a beautifully collectable example of ancient marine life from one of southern England’s important Jurassic fossil-bearing regions.
Sonninia ammonites are highly regarded by fossil collectors for their distinctive Jurassic character, strong scientific interest, and association with the richly fossiliferous Inferior Oolite deposits of Dorset and Somerset. This specimen is a carefully chosen piece, and the photo shows the actual fossil you will receive. Full sizing can be seen in the photo.
Fossil Type and Species
Ammonites were extinct marine cephalopods related to modern squid, cuttlefish, and nautiluses. They lived inside coiled, chambered shells and were among the most successful marine animals of the Jurassic seas. Their shells were divided into internal chambers, which helped the animal regulate buoyancy while swimming or drifting through the water column.
Sonninia propinquans belongs to the ammonite group known as the Sonniniidae, within the superfamily Hammatoceratoidea and order Ammonitida. Sonninia is a well-known Bajocian ammonite genus, especially associated with the early part of the Bajocian Stage. Species within this genus often display moderately evolute coiling, visible inner whorls, and ribbed ornamentation that may vary during growth. Many Sonninia specimens show strong, sweeping ribs and a compressed to moderately inflated shell profile, features that make them visually appealing and useful for palaeontological comparison.
The species propinquans was originally named by Bayle, and Sonninia ammonites are important within Lower Bajocian ammonite faunas because of their value in identifying and correlating Jurassic rock layers.
Geology and Formation
This ammonite comes from the Inferior Oolite Group, a famous Middle Jurassic rock unit found across parts of southern and western England. Despite the name “Inferior”, the term refers to its geological position beneath the Great Oolite, not to the quality of the fossils. The Inferior Oolite is well known for producing ammonites, brachiopods, bivalves, gastropods, echinoids, corals, and other marine fossils.
The rocks at and around Oborne Wood in Dorset belong to a marine Jurassic sequence deposited during the Bajocian. At this time, the region was covered by a warm, shallow sea. Sediments rich in shell debris, lime mud, and oolitic grains accumulated on the sea floor, eventually compacting and hardening into limestone and related sedimentary rocks. These conditions created an excellent environment for the preservation of ammonites and other marine invertebrates.
The Inferior Oolite environment was a dynamic shallow shelf setting, influenced by currents, changing water depths, and carbonate sedimentation. Fossils from these beds provide a direct window into the marine ecosystems that existed across what is now Dorset during the Middle Jurassic.
Lower Bajocian Age and Scientific Interest
The Lower Bajocian is the earlier part of the Bajocian Stage, within the Middle Jurassic Period. Ammonites from this interval are especially important because they evolved rapidly and are often used as index fossils. Their changing shell forms allow geologists and palaeontologists to compare and date rock layers across different localities.
Sonninia is particularly associated with Lower Bajocian ammonite zones, including faunas close to the Sonninia biohorizons recognised in the Inferior Oolite succession. This makes a named Sonninia specimen from Dorset more than just a decorative fossil; it is also a scientifically interesting example of Jurassic biostratigraphy.
Authenticity and Display
This fossil is supplied as a genuine specimen and includes a Certificate of Authenticity lifetime guarantee generic card. It is ideal for fossil collectors, Jurassic enthusiasts, educational collections, natural history displays, or anyone looking for an authentic British ammonite with strong geological provenance.
The specimen is from Oborne Wood, Dorset, UK, and is a carefully selected fossil with the photograph showing the exact piece you will receive. Its combination of named species, British locality, Middle Jurassic age, and certificate of authenticity makes it a desirable addition to any fossil collection.
Collectable British Jurassic Ammonite
A genuine Sonninia propinquans ammonite from the Inferior Oolite Group is a superb representation of Lower Bajocian marine life. With its Dorset origin, Jurassic age, and scientifically recognised ammonite genus, this fossil offers both display appeal and genuine palaeontological interest for collectors of British fossils, ammonites, and natural history specimens.
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