Description
Pleydellia mactra Ammonite Fossil from Bavaria
Genuine Upper Toarcian Specimen
This carefully chosen Pleydellia mactra ammonite is a genuine fossil specimen from Mistelgau near Bayreuth in Bavaria, Germany. The photographs show the exact fossil you will receive, allowing its individual preservation, colour, matrix and natural shell features to be viewed before purchase. Please use the sizing photograph for full dimensions and proportions.
Upper Toarcian Geological Age
The fossil dates from the Upper Toarcian, the final part of the Toarcian Stage of the Lower Jurassic, approximately 175 to 174 million years ago. During this interval, much of central Europe was covered by a marine basin connected to the wider Tethys Ocean. Fine mud and carbonate sediment accumulated on the seabed, preserving ammonites and other organisms that inhabited or drifted through these ancient waters.
Mistelgau is a well-known German Jurassic fossil locality. Its sedimentary sequence has yielded ammonites, belemnites, bivalves and remains of other marine animals. Specimens from a recognised locality provide valuable geological context because their age and depositional environment can be related to studied rock layers. This fossil therefore represents both an extinct animal and a physical record of Bavaria’s Jurassic marine history.
Species and Ammonite Morphology
Pleydellia mactra belongs to the Ammonoidea, an extinct group of shelled marine cephalopods related to modern squid, cuttlefish, octopus and nautilus. The shell contained internal chambers separated by septa. The animal lived in the final body chamber, while the remaining chambers and a connecting siphuncle helped manage buoyancy.
Pleydellia is generally placed within the family Hammatoceratidae and the order Ammonitida. Species of Pleydellia commonly display a compressed, discoidal shell with evolute to moderately involute coiling and fine to stronger ribbing. The whorl profile, umbilical width, rib pattern and ventral form are important identification features. Preservation may reveal original shell, mineral replacement or an internal mould formed after the shell dissolved.
Biostratigraphic Importance
Ammonites evolved rapidly and spread across large marine areas, making them excellent index fossils. Pleydellia is especially important in Upper Toarcian biostratigraphy. Characteristic species help palaeontologists identify ammonite zones and correlate marine rock sequences across Europe. A localised Pleydellia specimen therefore offers meaningful scientific interest alongside its decorative appeal.
Fossilisation and Natural Features
After death, the shell settled onto the sea floor and was buried by sediment. Continued burial led to compaction and mineralisation, while later uplift and erosion exposed fossil-bearing layers. Natural fissures, incomplete edges, matrix attachment, mineral staining, weathering and variations in colour are normal features of authentic fossils. Each specimen records a unique path through burial and preservation.
Collecting and Display
This German ammonite is ideal for a Jurassic fossil collection, geological teaching set, natural history display or cabinet of curiosities. It also makes an engaging gift for an ammonite collector, geology student or enthusiast of prehistoric marine life. The specimen pictured is the actual fossil supplied.
Certificate and Care
This is a genuine fossil and includes a generic Certificate of Authenticity card with a lifetime guarantee. Handle it over a soft surface, supporting both fossil and matrix. Avoid pressure on delicate edges, strong chemicals, washing and rapid changes in humidity or temperature. Display it in a dry, stable location and use gentle dry dusting when required.
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