PALAEONTOLOGY[online]

Tag: René Hoffmann

René Hoffmann is assistant professor at the Ruhr-Universität Bochum (Germany) with a research focus on fossil and extant cephalopods. He currently uses rare hollow Jurassic-Cretaceous ammonoid fossils in combination with high resolution scanning (micro-CT, nano-CT, and synchrotron radiation) to reconstruct ammonoid life habits, e.g. their buoyancy, swimming abilities, and shell mechanics. He finds reconstructing how organisms lived in the past one of the most fascinating topics in the field of palaeontology. Recently, he has been working together with the Konrad-Zuse-Institute (Berlin) in order to develop an improved image reconstruction algorithm which allows the use of ammonoid shells filled with sediment for similar purposes. Cephalopod shells do not only yield information about their construction, and hydrostatic stress resistance – allowing us to speculate about maximum diving depth – but also geochemical signals of their past environment are recorded in their carbonate shells. With those proxies (element ratios, stable isotope systems, or clumped isotopes) it is further possible to reconstruct the environment in which the ammonoids lived, e.g. seawater temperature, nutrient fluxes, and salinity. Analysing geochemical data through development and growth enable us to recognize changes during the life of one specimen, e.g. migrations from the north to the south or from shallow to deeper marine habits – indicated by temperature changes, which are also useful to reconstruct ancient climate

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Ruhr-Universität Bochum, Institut für Geologie, Mineralogie und Geophysik, Germany.

by Kenneth De Baets1, René Hoffmann2, Jocelyn A. Sessa3 and Christian Klug4. Introduction: Ammonoids (Ammonoidea) are an extinct group of marine invertebrates with an external shell. They were cephalopods, and hence closely related to modern cuttlefish, squid, octopuses and the pearly nautilus. In a non-scientific context, they are commonly called ammonites, but that term really includes only Jurassic and Cretaceous forms in its stricter scientific sense. The Ammonoidea as a whole lived from the Early Devonian to the earliest Palaeogene period, covering a timespan of about 350 million years. Normally, only their shells, also called conchs, or their internal moulds are found in the fossil record. Conchs from adult ammonoids range from about 5 millimetres to 2 metres in diameter. Due to...