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Holzmaden Pyrite Fossil Ammonoid Plate 544mm


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A substantially large sized Harpoceras pyritised ammonoid naturally encapsulated in Jurassic grey shale, which has helped conserve wonderfully the attributes of the ribbed shell. The large and prehistorically interesting Holzmaden plate exhibiting excellent preservation, the fossil having absorbed mineral inclusions of the bedding layers during the period of fossilisation which has taken over 150,000,000 years. Read more about the Nautiloid story below...

Genus: Harpoceras falcifer Class: Cephalopoda, Order Ammonitida, Family Hildoceratidae
Origin: Holzmaden region, Posidonia formation, Lagerstätten shales, South West Germany.
Age: Palaeozoic era, Lower Jurassic period, Toarcian stage, approximately 180 million years.

Holzmaden plate measurements.
Height: 54.4 cm
Width: 57.0 cm
Depth: 2.5 cm

Weight: TBC approximately 15 Kg


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Holzmaden ammonoidea plate, beautifully curated for interiors around the world. The Harpoceras ammonite exhibiting exquisitely detailed preservation with conservation of the fossilised Jurassic phragmacone (shell), once the home of a marine mollusc a cephalopod member related to modern-day cuttlefish and octopi of the cephalopoda group. The Harpoceras ammonite being part of the subclass Ammonoidea and a family Hildoceratidae. The extinct prehistoric molluscs shell has absorbed, through a process of an anoxic environment (lack of oxygen) in conjunction of a lack of organic bacterial growth, Iron pyrite has formed from the production of sulphur from simple algae. This caused an iron pyrite metamorphism to the decaying animal and shell during the fossilisation process, which has taken place over 180,000,000 years, the minerals of iron pyrite have developed in the form of the more commonly known fools gold. Fools gold is often found in the occurrence of gold ore and is used as an indication of a possible gold seam.

The surrounding shale has been carefully and precisely cut and fashioned from the fossil bed, prepared and finally conserved providing a fine naturalistic and aesthetically pleasing statement wall piece. The fossil inclusion within the plate is the natural fossil from the fossilisation of marine cephalopoda. Each fossil phragmacone exoskeleton (shell) demonstrates excellent detail; all the specimens feature fine ribbed and sizeable sized phragmacone's of type.

The Ammonites eventually becoming extinct in the Maastrichtian age, just before the mass KT extinction event. The Nautiloids survived probably due to their benthic ecology. Laying small batch eggs often, at depth or on the sea floor with more frequency, throughout their life, thus protecting the eggs from most significant climatic changes. Whereas the Ammonites laid one batch of numerous eggs at the end of life and attached these to marine planktonic environments, close to the surface which made them more susceptible to any significant planetary climatic change.