Pseudogrammoceras Ammonite Fossil from Upper Toarcian Jurassic Calvados France with Certificate of Authenticity
£ 24.00
GEOLOGICAL CONTEXTThis authentic Pseudogrammoceras ammonite fossil originates from the Upper
Toarcian Stage of the Jurassic Period, approximately 182–174 million years old. It was discovered in Calvados, France, a region of Normandy that is particularly well known for its beautifully preserved Jurassic ammonites. During the Toarcian, this area formed part of a shallow seaway connected to the Tethys Ocean. Sedimentation in this environment produced fine-grained shales and limestones, which created the perfect conditions for the fossilisation of ammonites. TAXONOMIC CLASSIFICATION
• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Ammonitida
• Superfamily: Hildoceratoidea
• Family: Hildoceratidae
• Genus: PseudogrammocerasAmmonites of this genus are regarded as highly important index fossils for the Upper Toarcian, aiding geologists in dating and correlating rock layers across Europe. Their distinctive morphology makes them easy to recognise and desirable to both researchers and collectors. MORPHOLOGICAL FEATURESThe fossil shows the characteristic planispiral, compressed shell typical of Pseudogrammoceras. Key features include:
• Discoidal shape with relatively flat sides and a narrow whorl section.
• Fine, closely spaced ribbing radiating across the shell flanks.
• Strongly defined ventral keel, which provided hydrodynamic stability when the animal was alive.
• Complex suture lines visible on the shell, marking the boundaries of the internal chamber walls.These traits highlight the ammonite’s evolutionary adaptations for efficient swimming and buoyancy control within the open marine environment. DEPOSITIONAL ENVIRONMENTThe Upper Toarcian was a time of fluctuating sea levels and widespread deposition of dark marine shales. In Calvados, the ammonites were preserved in low-energy, oxygen-poor seabeds, which reduced the decay of organic material and allowed remarkable detail to be retained in the fossil record. The fossil-bearing strata are part of the classic Normandy Jurassic sequences, which have been studied for more than a century and continue to yield scientifically valuable material. SCIENTIFIC AND COLLECTOR IMPORTANCE
• Biostratigraphy: Pseudogrammoceras is a key ammonite for identifying Toarcian subzones and dating marine deposits.
• Evolutionary Value: Represents an important lineage in the family Hildoceratidae.
• Collector’s Appeal: The fine ribbing, compressed profile, and elegant form make this a visually striking display piece.
• Educational Utility: Perfect for teaching about Jurassic ammonites, palaeobiology, and fossilisation processes. AUTHENTICITY AND PRESENTATION
• This specimen comes with a Certificate of Authenticity, guaranteeing it is a 100% genuine fossil.
• The photographs show the actual fossil you will receive, ensuring accuracy and transparency.
• Scale reference is provided with a 1 cm cube for exact sizing.This Pseudogrammoceras ammonite fossil from the Upper Toarcian of Calvados, France, is a scientifically significant and visually appealing specimen. With its elegant morphology and excellent preservation, it is an outstanding addition for serious fossil collectors, educators, or anyone fascinated by the ancient marine world of the Jurassic seas.
Toarcian Stage of the Jurassic Period, approximately 182–174 million years old. It was discovered in Calvados, France, a region of Normandy that is particularly well known for its beautifully preserved Jurassic ammonites. During the Toarcian, this area formed part of a shallow seaway connected to the Tethys Ocean. Sedimentation in this environment produced fine-grained shales and limestones, which created the perfect conditions for the fossilisation of ammonites. TAXONOMIC CLASSIFICATION
• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Ammonitida
• Superfamily: Hildoceratoidea
• Family: Hildoceratidae
• Genus: PseudogrammocerasAmmonites of this genus are regarded as highly important index fossils for the Upper Toarcian, aiding geologists in dating and correlating rock layers across Europe. Their distinctive morphology makes them easy to recognise and desirable to both researchers and collectors. MORPHOLOGICAL FEATURESThe fossil shows the characteristic planispiral, compressed shell typical of Pseudogrammoceras. Key features include:
• Discoidal shape with relatively flat sides and a narrow whorl section.
• Fine, closely spaced ribbing radiating across the shell flanks.
• Strongly defined ventral keel, which provided hydrodynamic stability when the animal was alive.
• Complex suture lines visible on the shell, marking the boundaries of the internal chamber walls.These traits highlight the ammonite’s evolutionary adaptations for efficient swimming and buoyancy control within the open marine environment. DEPOSITIONAL ENVIRONMENTThe Upper Toarcian was a time of fluctuating sea levels and widespread deposition of dark marine shales. In Calvados, the ammonites were preserved in low-energy, oxygen-poor seabeds, which reduced the decay of organic material and allowed remarkable detail to be retained in the fossil record. The fossil-bearing strata are part of the classic Normandy Jurassic sequences, which have been studied for more than a century and continue to yield scientifically valuable material. SCIENTIFIC AND COLLECTOR IMPORTANCE
• Biostratigraphy: Pseudogrammoceras is a key ammonite for identifying Toarcian subzones and dating marine deposits.
• Evolutionary Value: Represents an important lineage in the family Hildoceratidae.
• Collector’s Appeal: The fine ribbing, compressed profile, and elegant form make this a visually striking display piece.
• Educational Utility: Perfect for teaching about Jurassic ammonites, palaeobiology, and fossilisation processes. AUTHENTICITY AND PRESENTATION
• This specimen comes with a Certificate of Authenticity, guaranteeing it is a 100% genuine fossil.
• The photographs show the actual fossil you will receive, ensuring accuracy and transparency.
• Scale reference is provided with a 1 cm cube for exact sizing.This Pseudogrammoceras ammonite fossil from the Upper Toarcian of Calvados, France, is a scientifically significant and visually appealing specimen. With its elegant morphology and excellent preservation, it is an outstanding addition for serious fossil collectors, educators, or anyone fascinated by the ancient marine world of the Jurassic seas.
