Paleontologists around the world have a new method at their disposal to identify areas to dig for fossils: look for lichens, especially orange ones.
This is according to a study by the University of Reading published in Current Biologywhich quantified for the first time a phenomenon known anecdotally to paleontologists but never addressed systematically: the preference of certain lichen species for substrates containing fossils.
Scientific foundation. Once considered “only” a symbiosis between algae (or cyanobacteria) and fungi, today lichens are rightly considered real micro-ecosystems, “built” around a fungus and its collaboration with an autotrophic organism but which also see the involvement of other fungi and bacteria. Accustomed to surviving even in extreme conditions, lichens are pioneer organisms, among the first to colonize a new environment; this does not mean that they do not have preferences: they tend to favor basic, calcareous and porous soils, where they are able to take root better.
The spectral signature of lichens. It has long been known, on an anecdotal level, that where lichens grow it is easier to find fossils, to the point that it is often their presence that first indicates that an area could be rich in animal remains. The Reading team that conducted the study put this notion to the test by analyzing large areas of Alberta’s Dinosaur Provincial Park with the use of drones capable of identifying the so-called “spectral signature” of lichens.
I prefer bones. The analysis made it possible to identify two species of lichens in particular, Rusavskia elegans And Xanthomendoza trachyphyllaboth orange in colour: when they are found in an area rich in exposed fossil bones, they tend to colonize up to 50% of them, while the surrounding rocks, those without fossilized remains, are almost completely ignored (only 1% of them are colonised). According to the authors of the study, the reason is to be found in the composition of the fossils themselves, which are, in fact, basic, porous and calcareous.
It doesn’t work everywhere. The discovery promises to revolutionize paleontology, and in particular the methods used to search for new fossiliferous beds to excavate: where the rock is orange, and lichens are therefore present, it is more likely to find fossils. This will be especially helpful for the exploration of remote and difficult to reach areas: the presence of lichens, which can also be confirmed by a simple drone, indicates that it is worth investing in exploration.
However, it should be noted that, at least for now, the method is valid in areas such as Dinosaur Provincial Park, where it often happens that fossil bones remain exposed long enough to be colonized; as regards lichens in other fossiliferous areas, new studies will be needed to investigate further.
