A fossilised internal mould of a nautilus the Jurassic period (201Ma-145Ma.) This specimen is 8m in width, 10 cm in height and has a depth of 5cm. Nautilus belong to the phylum Mollusca and class cephlapoda, they can still be found today in the Indian ocean where they are observed as living fossils. This is a calcareous specimen, remineralised to crystalline calcite as a result of burial. Nautiloids are nektonic and are predators in the pelagic zone, they use jet propulsion to move around the water column and control their buoyancy by changing gas/liquid contents in their chambers. Nautilus fossils have been found, to date back, in their straight form from to the Cambrian to the Permian, in their curved form the fossils date back to the Devonian and living fossils are still observed today. This makes them an important index fossil for dating stratigraphy. http://gwydir.demon.co.uk/jo/fossils/nautiloid.htm https://igws.indiana.edu/FossilsAndTime/nautiloids.cfm
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