科研之友
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摘要
ObjectivesHigh-resolution imaging of fossils with X-ray computed microtomography (CT) has become a very powerful tool in paleontological research. However, fossilized bone, embedding matrix, and dental tissues do not always provide a distinct structural signal with X-rays. We demonstrate the benefits of high-resolution neutron radiation in three different specimens showing problematic contrasts with X-ray CT.
Materials and methodsWe compare neutron with X-ray CT scans of fossils from two Miocene catarrhines from the Valles-Penedes Basin: the cranium (IPS58443.1, holotype) of the putative stem hominoid Pliobates cataloniae, to discriminate between bone and matrix; and two lower molars (IPS1724n,o, holotype) of Barberapithecus huerzeleri, to discriminate among dental tissues.
ResultsX-ray CT scans of these specimens fail to retrieve any contrast between matrix/bone and enamel/dentine, whereas neutron CT scans deliver high-contrast images, enabling a proper evaluation of the specimens' internal anatomy.
DiscussionLow bone/matrix intensity difference with X-ray CT scans in IPS58443.1 is due to the extreme similarity in chemical composition between the matrix and the fossilized tissues, and the presence of high-density elements. In IPS1724, it is attributable to the convergence of enamel and dentine compositions during fossilization. On the contrary, neutron radiation returns very different contrasts for different isotopes of the same element and easily penetrates most metals. Neutron-based CT scans therefore enable a correct definition of the bone/sediment and enamel/dentine interfaces, and hence a better segmentation of the images stack. We conclude that neutron radiation represents a successful alternative for high-resolution mu CT of small-sized fossils that are problematic with X-rays.
- 出版日期2018-8
