APPLYING MICRO-CT IMAGING IN THE STUDY OF FOSSIL SEPIIDS AND NAUTILIDS (CEPHALOPODA): EXAMPLES FROM THE EOCENE OF BELGIUM

Micro-CT imaging is presented as an excellent tool for investigating the calcified remains of the skeleton of stem group sepiids, such as Belosaepia (Coleoidea), as it allows to produce an infinite number of virtual cross-sections in any possible direction through a specimen without damaging it. Growth increments can be easily identified and traced in three dimensions, enabling to inspect, visualize and quantify ontogenetic changes and episodes of resorption of previously secreted carbonate layers. As such, micro-CT imaging may enhance the precision of taxonomic assignments, and aid in estimating growth rates and longevity. The high signal to noise ratio of the obtained scanning results from specimens of various species from different stratigraphic units of the Belgian Eocene also allowed to produce high-quality surface images. The discovery of stratigraphically important microfossils (e.g. Nummulites) in sediment attached to some of the cephalopod fossils was of substantial help in the stratigraphic revision of specimens collected more than a century ago, in outcrops that are no longer accessible today. Similar high-quality outputs were obtained for several lower and upper jaws of nautilids, possibly related to the genus Cimomia, also coming from the Eocene of Belgium.