NEW METHODS TO DOCUMENT FOSSILS FROM LITHOGRAPHIC LIMESTONES OF SOUTHERN GERMANY AND LEBANON
We present different documentation methods tested on fossil specimens from Solnhofen-type lithographic limestones (Upper Jurassic, southern Germany) and from the related deposits from the Upper Cretaceous of Lebanon. One of the principles is composite imaging. This combines image fusion, i.e., coalescing several images of the same area but at different focal planes, resulting in a single image of high depth of field, and image stitching, i.e., combining fused images of several areas to a high resolution image of the complete specimen. The basis for the composite images can be normal light images, but most fossils from Solnhofen-type lithographic limestones are autofluorescent under UV light such that UV-fluorescence images can be equally well applied. In this context, we report a new fluorescence type for specimens not showing good UV fluorescence, i.e., those from the Zandt lagerstätte or some from Lebanon. These specimens fluoresce orange when exposed to green light. Specimens from Lebanon exhibiting green-orange fluorescence have been documented under a confocal laser scanning microscope (cLSM). Fossils showing a relatively high relief can be documented with stereo images; based on these surfaces, 3D models can be produced. A large specimen preserved uncompressed has been documented using a medical X-ray computer tomography scanner. All these methods facilitate the high-resolution documentation of complete specimens (= "virtual specimens"). Specimens from both Solnhofen-type lithographic limestones and Lebanon have further been examined for their elemental composition using energy dispersive X-ray spectroscopy (EDX). The fossils differ significantly from the surrounding matrix by containing 6–14% phosphorus.
Keywords: composite imaging; computed tomography; 3D visualisation; UV fluorescence; green-orange fluorescence; Solnhofen
PE Article Number: 12.3.6T
Copyright: Palaeontological Association December 2009
Submission: 16 March 2009. Acceptance: 15 October 2009