Dr. Paul Tafforeau; ESRF, Grenoble, France

Since several years, non-destructive analysis of fossils are becoming more and more necessary. Among all these techniques, imaging represent the most developed aspect, mainly through X-ray tomography and microtomography. Despite the fact that most of these analysis are performed using conventional X-ray sources, it is also possible to use 3rd generation synchrotron sources.

Synchrotron based investigations enable very high quality non-destructive X-ray microtomographic imaging of fossils. The advantages of X-ray synchrotron microtomography over conventional microtomography involve several important physical properties of the X-ray beams produced by a synchrotron: Firstly, monochromatisation avoids beam hardening that is frequently severe for paleontological samples, and allows quantitative analysis of densities. Secondly, the high beam intensity available at synchrotron radiation sources allows rapid data acquisition on wide range of spatial resolutions, resulting in high quality imaging of the internal structures of the sample. Thirdly, the parallel geometry of the beams allows to use exact tomographic reconstruction algorithms leading to higher resolution for a given pixel size relatively to a conventional microtomograph. Finally, high beam coherence leads to additional imaging possibilities: phase contrast radiography, phase contrast microtomography and holotomography. These methods greatly improve the image contrast and therefore allow the study of fossils that cannot be investigated by conventional microtomography either due to a high degree of mineralization or low absorption contrast.

Thanks to these different properties and imaging techniques, a third generation synchrotron radiation source, and the ESRF in particular, appears as an almost ideal investigation tool for palaeontologists. This talk will present different imaging techniques and the palaeontological issues that can be addressed using several examples, as well as the ongoing developments of paleontological imaging at the ESRF.


Examples of fossils imaged at the ESRF with increasing sizes: a Palaeozoic charophyte, a Miocene rodent molar, a Cretaceous insect in amber, an Eocene dermopteran, an Eocene primate, and a Miocene hominoid will be shown during the presentation.