Laser-Stimulated Fluorescence in Paleontology

Abstract

Fluorescence using ultraviolet (UV) light has seen increased use as a tool in paleontology over the last decade. Laser-stimulated fluorescence (LSF) is a next generation technique that is emerging as a way to fluoresce paleontological specimens that remain dark under typical UV. A laser’s ability to concentrate very high flux rates both at the macroscopic and microscopic levels results in specimens fluorescing in ways a standard UV bulb cannot induce. Presented here are five paleontological case histories that illustrate the technique across a broad range of specimens and scales. Novel uses such as back-lighting opaque specimens to reveal detail and detection of specimens completely obscured by matrix are highlighted in these examples. The recent cost reductions in medium-power short wavelength lasers and use of standard photographic filters has now made this technique widely accessible to researchers. This technology has the potential to automate multiple aspects of paleontology, including preparation and sorting of microfossils. This represents a highly cost-effective way to address paleontology's preparatory bottleneck.

Laser Fluorescence Illuminates the Soft Tissue and Life Habits of the Early Cretaceous Bird Confuciusornis

“…In this way only the fluorescence coming from the specimen is recorded. See Kay et al [19] for further details on the methodology of laser-stimulated fluorescence.…”

“…The rachises of specimen IVPP V13156 are robust (contra to [5; 8,9]), with the thickest measuring >1.5 mm (Fig 5), and are clearly visible under both white light and laser fluorescence. The rachis itself does not fluoresce; as explained by Kaye et al [19], the matrix behind the feathers fluoresces, which causes a “backlit” phenomenon, highlighting detail. This suggests that no organics are preserved in the rachis itself.…”

“…[16–18]), but has only recently been successfully applied to macrofossils [19]. LSF is a highly successful and versatile method that can be used to identify potentially modified fossils, highlight hidden structures, and, as this study shows, fluoresce soft tissues otherwise invisible under white light.…”

Multispectral and colour imaging systems for the detection of small vertebrate fossils: A preliminary study

“…An improved method might be obtained with the combination of this technique with the new advances on laser-stimulated fluorescence in fossils (Kaye et al, 2015).…”

“…However, this method cannot be universally used since fluorescence properties depend on the type of fossils analysed and limits of light exposure exist in relation to the preservation of paleontological remains. To circumvent this last aspect, Kaye and colleagues (Kaye et al, 2015) recently explored the possibilities of laser stimulation to enhance the fluorescent properties of fossils and developed the prototype of an automated micro-fossil picker (Kaye et al, 2015, figure 10). However, further research is still needed with regard to the spectral features of different types of fossils to overcome some of the limitations in fossil detection.…”