CASTING, REPLICATION, AND ANAGLYPH STEREO IMAGING OF MICROSCOPIC DETAIL IN FOSSILS, WITH EXAMPLES FROM CONODONTS AND OTHER JAWLESS VERTEBRATES

ABSTRACT

Sophisticated techniques, such as computed tomography and scanning light microscopy, allow palaeontologists to image the microscopic details of fossils even when scanning electron microscopy cannot be used. Occasionally these techniques are not always applicable, and where this is the case, methods involving fossil replication offer an alternative. I describe here a series of techniques for moulding, casting, imaging, and three-dimensional illustration of microfossils (or microscopic details of larger fossils). For moulding fossils (or casting mouldic specimens), room temperature vulcanizing silicon rubber provides a strong and flexible medium with low levels of shrinkage. RTV rubbers are also capable of replicating microscopic details of only a few micrometres. Similarly, epoxy resins are rigid, durable, and long lasting. In combination with RTV silicon rubber moulds, epoxy casts offer higher levels of resolution than any other medium. Details of specific RTV rubbers and epoxy resins that are widely available and work well with small fossils are provided.

For imaging, the advantages of stereophotography to illustrate fossils have long been appreciated, but the use of stereo-pairs is limited by their maximum size (generally only 5 or 6 centimetres). With the widespread availability of powerful image editing software, it is now a straightforward matter to produce anaglyph stereo images of any size. I provide step-by-step instructions and a set of actions to automate the process in Adobe Photoshop®. Anaglyph stereo images can be extremely useful research tools in their own right, but combined with electronic communication and publication they offer a simple and inexpensive means for illustrating fossils, and their microscopic details, in three-dimensions.

Mark A. Purnell. Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, UK.

KEY WORDS: casting, molding, microfossils, silicon rubber, epoxy