Cross-polarized light as an imaging technique for graptolites

Abstract

Photography using cross-polarized light is a standard technique for certain types of fossils such as Burgess Shale material; however, the technique has not been used for photography of graptolites. Here we demonstrate that cross-polarized illumination is useful for obtaining high-quality images of graptolites. The technique can also facilitate visualization of fusellar banding, allowing fossils of uncertain affinity to be identified as graptolites.

Lucy A. Muir [[email protected]], Department of Natural Sciences, Amgueddfa Cymru – National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK; Lucy M.E. McCobb [[email protected]], Department of Natural Sciences, Amgueddfa Cymru – National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK; Yuandong Zhang* [[email protected]], CAS Key Laboratory of Economic Geology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road, Nanjing 210008, PR China; *also affiliated with University of Chinese Academy of Sciences, Beijing 100049, PR China.

Keywords:

• Graptolithina
• Graptoloidea
• photography

Acknowledgements

The Leica microscope and ringlight and the GX camera were purchased by means of crowdfunding, including a Holloway grant from the Warwickshire Geological Conservation Group. We are grateful to all who contributed. LMEM acknowledges the support of Amgueddfa Cymru-National Museum Wales. Finally, we also thank two anonymous reviewers for their helpful comments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by a Chinese Academy of Sciences President’s International Fellowship Initiative [grant number 2018VCB0014] to LAM.