Description
Genuine Parkinsonia ferrisi Ammonite Fossil
This carefully chosen specimen is a genuine Parkinsonia ferrisi ammonite fossil from Calvados in Normandy, France. It originates from the Poitou Formation and dates to the Upper Bajocian interval of the Middle Jurassic, representing an extinct marine cephalopod that lived approximately 168–170 million years ago.
The combination of an identified species, recognised geological formation, precise Jurassic interval and recorded French locality gives this fossil excellent scientific, educational and collectable interest. It would make an attractive addition to a collection of ammonites, French fossils, Middle Jurassic specimens or natural-history objects.
The photograph shows the exact fossil specimen you will receive. Full sizing and scale information can be seen in the accompanying photograph.
Upper Bajocian Middle Jurassic Geology
The Bajocian is a stage of the Middle Jurassic Period and takes its name from the historic Normandy town of Bayeux. During the Upper Bajocian, the area now forming north-western France was influenced by warm, shallow marine environments connected to the wider Jurassic seas of western Europe.
Carbonate-rich mud, shell fragments and other marine sediments accumulated across the seabed. Over immense spans of geological time, these deposits were compacted and cemented into fossil-bearing limestone and related sedimentary rocks. The resulting formations preserve evidence of a diverse marine ecosystem containing ammonites, belemnites, nautiloids, brachiopods, bivalves, gastropods, echinoids and other invertebrates.
After death, an ammonite shell could sink to the seabed and become buried by sediment. The original shell material might subsequently be preserved, mineralised or dissolved, leaving an impression or internal mould of the chambered shell. Mineral-rich groundwater, burial pressure, sediment chemistry and later weathering all contributed to the appearance of the fossil seen today.
Natural differences in colour, texture, completeness, mineral staining and surrounding matrix are authentic results of fossilisation. These characteristics make every genuine Jurassic ammonite a unique geological specimen.
Parkinsonia ferrisi Shell Characteristics
Parkinsonia is a distinctive genus of Middle Jurassic ammonites belonging to the family Parkinsoniidae within the order Ammonitida. Members of the genus are particularly associated with the later part of the Bajocian and are well known for their evolute, strongly ornamented shells.
An evolute ammonite has relatively exposed inner whorls and a broad, clearly visible umbilical region. Typical Parkinsonia ornamentation consists of pronounced radial ribs that extend across the shell flanks. These ribs may divide as they approach the outer part of the whorl, creating the characteristic sculptured appearance associated with the genus.
The ventral region around the shell’s outer circumference may show an interruption or weakening of the ribs along the midline. Shell proportions, rib spacing, rib division, whorl section and changes in ornamentation during growth are all important features used when distinguishing Parkinsonia species.
Depending on its individual preservation, this Parkinsonia ferrisi specimen may display portions of the coiled whorls, ribbed flanks, open umbilical region, ventral margin, internal chambers or surrounding Jurassic matrix. Its preserved form records both the biological growth of the ammonite and the geological events that affected the shell after death.
An Extinct Marine Cephalopod
Ammonites were marine molluscs related to modern squid, cuttlefish, octopuses and nautiluses. Unlike most living cephalopods, they possessed a coiled external shell divided internally into a series of chambers.
The living animal occupied the final and largest section, known as the body chamber. The earlier chambers formed the phragmocone, a buoyancy structure connected by a narrow tube called the siphuncle. By regulating the balance of liquid and gas within the chambers, the ammonite could control its position in the water.
As the animal grew, it constructed progressively larger chambers around the outside of the shell. The partitions between these chambers met the shell wall along intricate patterns called suture lines. These sutures, together with the shell’s ribbing, coiling, whorl proportions and ventral structure, help palaeontologists classify ammonite fossils.
Ammonites evolved rapidly and became widely distributed through ancient marine environments. Their fossils are therefore valuable for biostratigraphy, allowing geologists to identify, compare and correlate Jurassic rock layers across different regions.
Calvados Fossil from Normandy, France
Calvados is internationally important in the history of Jurassic geology and palaeontology. The fossil-bearing rocks of Normandy have been studied for generations and preserve a detailed record of changing marine environments during the Jurassic Period.
The Bajocian Stage itself was established from the geology around Bayeux, making ammonites from Calvados particularly relevant to the scientific history of this interval. Fossils from the region provide evidence of ammonite evolution, ancient marine biodiversity, sedimentation and the geographical connections between Jurassic seas.
A specimen retaining its species identification, formation, geological age and locality has greater scientific and collectable significance than an ammonite without accompanying geological information. This Parkinsonia ferrisi is suitable for a specialist ammonite collection, educational display, geological study cabinet or distinctive natural-history gift.
Actual Specimen with Certificate of Authenticity
This is a genuine fossil and not a cast, replica or reproduction. It has been individually selected for its natural appearance, geological character and collectable appeal.
The photograph shows the actual Parkinsonia ferrisi ammonite fossil you will receive. Full sizing is shown in the photograph.
A generic Certificate of Authenticity card is included with a lifetime guarantee of authenticity, providing lasting confidence that this is a genuine Middle Jurassic fossil specimen.
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