Holzmaden ammonoidea plate, beautifully curated for interiors around the world. The ammonites 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 Lytoceras ammonite being part of the subclass Ammonoidea and a family Lytoceratidae. 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 fashioned from the shale fossil layer, prepared and finally conserved, finished with Italian waxes, providing a beautiful, naturalistic and aesthetically pleasing statement plate. The fossil inclusion and plate are completely naturally formed from the fossilisation of shells and of the mineral inclusions within the earth. Each Lytoceras siemensi demonstrates excellent detail of the phragmacone exoskeleton (shell), all three large specimens feature fine ribbed sizeable phragmacone's.
The ammonoids are an enigmatic group of extant cephalopods, along with modern-day cephalopods like nautiloids, such as the Nautilus pompilius and Nautilus umbilicalis which survive today in the S.W.Pacific ocean. With ancestral lineage reaching back to the late Permian to Ordovician periods. Since evolving Nautiloids have suffered extinctions in the Devonian, Carboniferous and Cretaceous periods. In fact, the Nautiloids seem to be in a state of contraction for much of this varied history. Seemingly in decline as the Ammonites were increasing successfully and in variety, a direct reflection of the ecology of the prehistoric marine environment in relation to both of these cephalopod family branches.
The Ammonites eventually becoming extinct in the Maastrichtian age, just before the mass KT extinction event. It is theorised 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 planetary climatic change.
Nautili are nektobenthic carnivores and pelagic in habit. The umbilicus of this shell of the genus is involute and globose. Cenoceras described by Hyatt C.1884,, Pseudocenoceras by Sparth C.1927.