Utility of high resolution x-ray computed tomography (HRXCT) for paleobotanical studies: an example using London Clay fruits and seeds

High resolution x-ray computed tomography (HRXCT) was used to image pyritized fossil fruits from the Lower Eocene London Clay flora to test the utility of this technique for paleobotanical application. The combination of carbon-pyrite preservation and void spaces between fruit and seed layers within fossils provides differences in density and composition that enable excellent imaging. Fossil fruits of Palaeorhodomyrtus subangulata (Bowerbank) Reid & Chandler (Myrtaceae) were investigated in situ within their silicone fluid conservation medium, which protects these unstable fossils from oxygen and humidity. HRXCT recovers taxonomically informative anatomical and morphological detail and provides a means of nondestructive examination of delicate type materials and other important specimens. These results suggest that HRXCT will be applicable to a broad spectrum of pyritized fossils to record structural details in inherently unstable materials. Key words: fossil fruits and seeds; high resolution x-ray computed tomography (HRXCT); London Clay; paleobotanical techniques; pyrite permineralization.