Description
Genuine Emileia (Otoites) cf. delicatus Ammonite Fossil
This carefully chosen fossil is a genuine Emileia (Otoites) cf. delicatus ammonite from the Inferior Oolite Group at Sandford Lane Quarry, Sherborne, Dorset, UK. It dates from the Bajocian Stage of the Middle Jurassic and is recorded from the Sauzei Zone, an important ammonite biozone within the Lower Bajocian succession.
The photograph shows the actual fossil specimen you will receive, allowing its natural shell form, ribbing, mineralisation, colouration, preservation and surrounding matrix to be examined before purchase. This is an individually selected fossil rather than a representative stock example.
The abbreviation “cf.” means “compare with” and indicates that the specimen displays features closely comparable with delicatus, while allowing for the natural limitations that can occur when a fossil is incomplete, partly concealed by matrix or does not preserve every feature required for an absolute species-level identification.
Lower Bajocian Sauzei Zone Fossil
The Sauzei Zone is a recognised biostratigraphic division of the Lower Bajocian. Ammonite zones are defined by characteristic fossil assemblages and allow geologists to identify and correlate marine sedimentary rocks with considerable precision.
Ammonites are especially valuable index fossils because many species evolved relatively rapidly and were distributed across extensive Jurassic seas. Changes in shell coiling, whorl proportions, ribbing, tuberculation and ventral structure allow palaeontologists to distinguish successive ammonite faunas and compare fossil-bearing beds between Britain and continental Europe.
A specimen recorded from the Sauzei Zone therefore carries clear geological context in addition to its visual and collectable appeal. It represents a specific interval within the early Middle Jurassic and preserves evidence of the diverse cephalopod communities that occupied the north-west European marine basin.
Emileia and Otoites Shell Characteristics
Emileia and Otoites are associated with strongly ornamented Bajocian ammonites characterised by robust ribbing and distinctive shell proportions. Their shells were planispirally coiled, meaning that each new whorl developed around the earlier growth stages within a single plane.
The central opening, known as the umbilicus, may expose parts of the inner whorls. Strong primary ribs typically originate near the umbilical region and extend across the flanks. These ribs can strengthen into raised nodes or tubercles before dividing into finer secondary ribs towards the outer edge of the shell.
In forms compared with delicatus, the ribbing may appear comparatively fine, regular or closely spaced. The exact appearance depends on the growth stage represented, the degree of preservation and the amount of shell exposed from the surrounding rock.
Juvenile whorls can display denser ornamentation and more pronounced tubercles, while later growth stages may develop broader whorls, changing rib spacing or a modified shell profile. These growth-related changes are important when studying and identifying Bajocian ammonites.
Inferior Oolite Group Geology
The Inferior Oolite Group is one of southern England’s most important fossil-bearing Middle Jurassic rock successions. It includes oolitic limestones, sandy limestones, marls, iron-rich deposits and condensed fossil horizons formed under changing shallow-marine conditions.
Oolitic limestone contains small rounded carbonate grains called ooids. These formed when calcium carbonate accumulated in repeated coatings around tiny sediment particles or shell fragments moving through warm, agitated seawater. The grains eventually settled onto the seabed, where compaction and natural cementation transformed the sediment into limestone.
Deposition within the Inferior Oolite sea was frequently interrupted by changing sea levels, current activity and variations in sediment supply. Shells could remain exposed on the seabed, become worn or reworked and later collect within fossil-rich horizons before final burial.
These processes helped create the diverse ammonite assemblages for which the Inferior Oolite Group is renowned. The associated marine fauna included belemnites, brachiopods, bivalves, gastropods, echinoids and numerous other invertebrates.
Sandford Lane Quarry, Sherborne
Sandford Lane Quarry near Sherborne is associated with fossil-bearing Jurassic strata in north-west Dorset. Inland quarries and former workings around Sherborne have produced scientifically important ammonites from several levels of the Inferior Oolite succession.
During the Bajocian, the Sherborne area formed part of a warm shallow sea connected to extensive marine basins across western Europe. Changing water depths, currents and sedimentary conditions created a varied sequence of fossil-bearing deposits.
A specimen with documented provenance from Sandford Lane Quarry has added scientific and collectable interest. It connects the fossil directly to a recognised Dorset locality and to the long-established history of geological research and fossil collecting around Sherborne.
Scientific Classification and Geological Details
Fossil type: Ammonite
Scientific identification: Emileia (Otoites) cf. delicatus
Family: Otoitidae
Superfamily: Stephanoceratoidea
Order: Ammonitida
Geological period: Jurassic
Geological epoch: Middle Jurassic
Geological stage: Bajocian
Biozone: Sauzei Zone
Geological unit: Inferior Oolite Group
Locality: Sandford Lane Quarry, Sherborne, Dorset, United Kingdom
Otoitid ammonites are characteristic components of Lower Bajocian marine faunas. Their strongly ribbed and tuberculate shells make them visually distinctive, while their stratigraphic distribution gives them considerable value in the study of Middle Jurassic rocks.
Chambered Shell and Marine Lifestyle
The living ammonite occupied the final and largest part of the shell, known as the body chamber. Earlier sections were divided internally by curved walls called septa, forming a sequence of chambers collectively known as the phragmocone.
A narrow tube called the siphuncle connected the chambers and allowed the animal to regulate their liquid and gas content. This helped control buoyancy and position within the Jurassic water column.
Where the septa met the inner shell wall, they formed patterned suture lines. These may become visible where the original outer shell has been naturally weathered, dissolved during fossilisation or carefully exposed during preparation.
Ammonites belonged to the cephalopods, the wider group of marine molluscs that includes modern squid, cuttlefish, octopuses and nautiluses. They were highly successful throughout much of the Mesozoic Era and developed an extraordinary range of shell forms and ornamentation.
Natural Fossilisation and Preservation
After the ammonite died, its shell settled onto the Jurassic seabed or was moved by currents before burial. Sediment gradually entered and covered the shell, helping protect portions of it from complete destruction.
Over millions of years, geological pressure and mineral-rich groundwater transformed the surrounding sediment into rock. The original shell may have been preserved, mineralised, replaced or dissolved, leaving a natural internal mould. Some specimens retain a combination of altered shell material, sediment-filled chambers and attached matrix.
Any incomplete areas, worn ribbing, minor fractures, mineral-filled sections, natural colour variations or surrounding rock are authentic geological characteristics. These features record the specimen’s burial, fossilisation, exposure and recovery and make every genuine fossil unique.
Collectable Dorset Jurassic Ammonite
This Emileia (Otoites) cf. delicatus ammonite fossil would make an excellent addition to a collection of British fossils, Dorset ammonites, Lower Bajocian fossils, Sauzei Zone specimens or Inferior Oolite fossils. Its documented identification, biozone and quarry locality also make it suitable for geological study, an educational display, fossil cabinet, office or distinctive gift for a Jurassic fossil enthusiast.
This is a 100% genuine fossil specimen and includes a Certificate of Authenticity generic card with a lifetime guarantee. The fossil has been carefully selected for its collectable qualities, and the photograph shows the exact specimen that will be supplied.
Full sizing please see photo.
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