Three dimensional photography of fossils (Part 3): Ammonites from the Northern Limestone Alps of Austria

Dr Robert Sturm As a result of their great diversity in shape and long-lasting occurrence in earth history (from the Devonian to the Cretaceous), ammonites are equally fascinating objects for the professional and amateur palaeontologist. By definition, ammonites exclusively comprise a group of extinct marine cephalopods that, according to the present store of knowledge, include about 1,500 genera and between 30,000 and 40,000 species. The shell size of adult animals ranged from a few centimetres to two metres in the case of Parapuzosia seppenradensis (Lehmann, 1981; Monks and Palmer, 2002). The introduction of ammonites into zoological systematics was carried out by Carl Alfred von Zittel in 1884, who defined the sub-class ‘Ammonoidea’. This unconventional term dates back to the first century AD, when the elder Pliny interpreted these fossils as horns of the ancient Egyptian god Amun. Since the petrified shells represent the most important relics of ammonites, information on their biology and anatomy is characterised by a number of uncertainties. For example, it is assumed that these cephalopods only possessed a small number of tentacles (eight to ten) and also an ink pouch, or bursa, for protection against natural enemies. Most species lived in a water depth of between 50m and 250m, where they mainly fed on crustaceans, foraminifers, and ostracods. Ammonites were also characterised by sexual dimorphism – the smaller individuals were males and the larger ones were females. Palaeontological determination of single species is chiefly based on the shape, size, sculpture and torsion of the shell, as … Read More

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