Description
Genuine Passendorfia anguiliculus Ammonite Fossil
This carefully selected fossil specimen is an authentic Passendorfia anguiliculus ammonite from France, dating to the Middle Oxfordian interval of the Upper Jurassic. It represents an extinct marine cephalopod that lived in the warm seas covering parts of Europe approximately 160 million years ago.
The photograph shows the actual fossil you will receive, allowing you to examine its individual preservation, natural colouration, shell form and remaining surface detail before purchase. This is not a stock photograph or a generic example. Full sizing and proportions are shown in the accompanying photographs.
Species and Shell Morphology
Passendorfia anguiliculus possessed the distinctive planispirally coiled shell associated with ammonites. Species of Passendorfia are generally recognised by their evolute shell form, in which the inner whorls remain visible around a comparatively open central umbilicus. The whorls commonly display radial ribbing that changes as the animal grows.
Ribs may begin near the umbilical region before extending across the flanks and dividing into finer secondary ribs towards the outer margin. These patterns of rib spacing, rib division, whorl shape and umbilical width are among the morphological characteristics used by palaeontologists when studying Oxfordian ammonites.
Natural constrictions may also occur on some examples of Passendorfia. These transverse grooves are associated with pauses or changes in shell growth and can provide valuable information about the development of the living ammonite. French representatives of the genus are particularly associated with Oxfordian marine deposits, including strata from the fossil-rich regions of western France.
Life in the Jurassic Sea
Ammonites were marine molluscs related to living squid, octopuses, cuttlefish and nautiluses. Unlike the soft-bodied squid and octopus, ammonites possessed a strong external shell divided internally into a series of chambers.
The living animal occupied the final and largest section, known as the body chamber. Earlier chambers were separated by walls called septa and connected by a narrow tube called the siphuncle. By regulating the fluids and gases within these chambers, the ammonite could control its buoyancy and move through different levels of the water column.
The shell provided protection while its streamlined spiral shape assisted movement through the sea. Ammonites probably fed on small marine animals, crustaceans and other available organic material, while also forming part of the food chain for larger Jurassic predators.
Middle Oxfordian Upper Jurassic Geology
The Oxfordian is the earliest stage of the Upper Jurassic Series. The Middle Oxfordian represents an interval within this stage when extensive shallow marine environments covered large parts of present-day France and neighbouring areas of Europe.
Sediments accumulated on the seabed as layers of carbonate-rich mud, marl and limestone. These deposits preserved an abundant marine fauna that included ammonites, belemnites, bivalves, brachiopods, echinoids and other invertebrates. Oxfordian ammonites are particularly important to geological research because their rapidly changing shell forms allow individual rock sequences to be compared and divided into relatively precise intervals.
The genus Passendorfia is documented from Middle Oxfordian ammonite assemblages and has been used in the interpretation and correlation of Jurassic marine strata. Some French Passendorfia occurrences have been recorded within the Transversarium ammonite zone, although this listing retains the broader Middle Oxfordian age supplied with this individual specimen.
Fossilisation and Natural Preservation
After the ammonite died, its shell descended to the Jurassic seabed and was gradually covered by sediment. Burial reduced exposure to scavengers, currents and physical erosion. As additional sediment accumulated, pressure and mineral-rich groundwater transformed the surrounding material into sedimentary rock.
During fossilisation, the original shell may have been preserved, replaced by minerals or dissolved to leave a mould subsequently filled with sediment or crystalline material. Many ammonites are therefore preserved as internal moulds that reproduce the shape of the shell’s chambers while retaining areas of external ribbing and ornamentation.
Minor chips, fractures, worn areas, matrix attachment and variations in surface texture are normal characteristics of genuine fossils. These natural features reflect the specimen’s burial, mineralisation and geological history rather than modern manufacture.
Collectable French Ammonite Specimen
This Passendorfia anguiliculus ammonite is an appealing addition to a collection of Jurassic fossils, French ammonites, prehistoric marine life or natural-history specimens. Its named identification, Middle Oxfordian age and French provenance give it both decorative and educational interest.
It would make a distinctive display fossil for a cabinet, study collection, office, classroom or home, as well as a memorable gift for an ammonite collector, geology enthusiast or anyone fascinated by prehistoric oceans.
The fossil has been individually chosen for its collectable qualities. The photographs show the exact specimen that will be supplied, and full sizing can be seen in the images.
This is a 100% genuine fossil specimen and includes a generic Certificate of Authenticity card with a lifetime guarantee.
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