Laser-stimulated fluorescence reveals unseen details in fossils from the Upper Jurassic Solnhofen Limestones

Abstract

Laser-stimulated fluorescence (LSF) has seen increased use in palaeontological investigations in recent years. The method uses the high flux of laser light of visible wavelengths to reveal details sometimes missed by traditional long-wave ultraviolet (UV) methods using a lamp. In this study, we compare the results of LSF with UV-A-generated fluorescence on a range of fossils from the Upper Jurassic Solnhofen Limestone Konservat-Lagerstätte of Bavaria, Germany. The methodology follows previous protocols of LSF with modifications made to enhance laser beam intensity, namely keeping the laser at a constant distance from the specimen, using a camera track. Our experiments show that along with making surface details more vivid than UV-A or revealing them for the first time, LSF has the additional value of revealing shallow subsurface specimen detail. Fossil decapods from the Solnhofen Limestone reveal full body outlines, even under the matrix, along with details of segmentation within the appendages such as limbs and antennae. The results indicate that LSF can be used on invertebrate fossils along with vertebrates and may often surpass the information provided by traditional UV methods.

Discovery of Ammonoid Jaw Apparatus and Associated Features Using Reflectance Transformation Imaging (Rti)

“…Specifically for extinct cephalopods like the ammonoids, this kind of technical innovations have been key to the description of structures which would have been rarely found in this group otherwise. Examples include the employment of a wide variety of tomographic techniques such as grinding tomography, X-ray microtomography, synchrotron tomography, and neutron tomography (e.g., Hoffmann et al, 2013;Tajika et al, 2015;Takeda et al, 2016;Kruta et al, 2020;Cherns et al, 2021;Smith et al, 2021;Tanabe et al, 2021), laser-induced fluorescence (Barlow et al, 2021), and digitization techniques such as surface or 3D scanning and photogrammetry (Peterman et al, 2019(Peterman et al, , 2020. Ammonoids are extinct cephalopods that appeared during the Early Devonian and went extinct at the Cretaceous/Paleogene boundary, with a few members eventually surviving into the earliest Paleogene (Landman et al, 2015).…”