Fossil Record 18(2): 127-135, doi: 10.5194/fr-18-127-2015
Lichen preservation in amber: morphology, ultrastructure, chemofossils, and taphonomic alteration
expand article infoC. Hartl, A. R. Schmidt§, J. Heinrichs|, L. J. Seyfullah§, N. Schäfer, C. Gröhn, J. Rikkinen#, U. Kaasalainen
‡ Department of Geobiology, University of Göttingen, Goldschmidtstraße 3, 37077 Göttingen, Germany§ Courant Research Centre Geobiology, Georg-August-Universität Göttingen, Goldschmidtstraße 3, 37077 Göttingen, Germany| Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Abteilung Systematische Botanik, Georg-August-Universität Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany¶ Amber Study Group, c/o Geological-Palaeontological Institute and Museum of the University of Hamburg, Bundesstraße 55, 20146 Hamburg, Germany# Department of Biosciences, P.O. Box 65, 00014 University of Helsinki, Helsinki, Finland
Open Access
The fossil record of lichens is scarce and many putative fossil lichens donot show an actual physiological relationship between mycobionts andphotobionts or a typical habit, and are therefore disputed. Amber haspreserved a huge variety of organisms in microscopic fidelity, and so thestudy of amber fossils is promising for elucidating the fossil history oflichens. However, so far it has not been tested as to how amber inclusions oflichens are preserved regarding their internal characters, ultrastructure,and chemofossils. Here, we apply light microscopy, scanning electronmicroscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Ramanspectroscopy to an amber-preserved Eocene lichen in order to gaininformation about the preservation of the fossil. The lichen thallusdisplays lifelike tissue preservation including the upper and lower cortex,medulla, photobiont layer, apothecia, and soredia. SEM analysis revealedglobular photobiont cells in contact with the fungal hyphae, as well as impressionsof possible former crystals of lichen compounds. EDX analysis permitted thedifferentiation between halite and pyrite crystals inside the lichen whichwere likely formed during the later diagenesis of the amber piece. Ramanspectroscopy revealed the preservation of organic compounds and a differencebetween the composition of the cortex and the medulla of the fossil.