Un petit morceau de plante fossile du Rhin avec des champignons fossiles colonisant les membres, vu au microscope. Crédit : Loron et al.
Une technologie de pointe a révélé de nouvelles informations sur un trésor de fossiles de renommée mondiale, qui pourraient fournir des indices importants sur les débuts de la vie sur Terre.
Les scientifiques qui enquêtent sur la cache de fossiles vieille de 400 millions d’années, découverte dans la région reculée du nord-est de l’Écosse, rapportent que leurs résultats montrent un niveau de préservation moléculaire plus élevé dans ces fossiles que prévu.
Un nouvel examen du trésor magnifiquement préservé de l’Aberdeenshire a permis aux scientifiques d’identifier les empreintes chimiques des divers organismes qui s’y trouvent.
Tout comme la pierre de Rosette a aidé les égyptologues à traduire les hiéroglyphes, l’équipe espère que ces symboles alchimiques aideront à mieux comprendre l’identité des formes de vie, qui sont représentées par d’autres fossiles plus obscurs.
Minéralisé et recouvert de roche dure composée de silice, l’étonnant écosystème fossile a été découvert près du village de Rhynie dans l’Aberdeenshire en 1912. Connu sous le nom de Rhynie chert, il provient du début du Dévonien – il y a environ 407 millions d’années – et joue un rôle important dans la compréhension des scientifiques de la vie sur Terre.
Les chercheurs ont combiné les dernières avancées en matière d’imagerie non destructive, d’analyse de données et[{ » attribute= » »>machine learning to analyze fossils from collections held by National Museums Scotland and the Universities of Aberdeen and Oxford. Scientists from the University of Edinburgh were able to probe deeper than has previously been possible, which they say could reveal new insights about less well-preserved samples.
Employing a technique known as FTIR spectroscopy – in which infrared light is used to collect high-resolution data – researchers found impressive preservation of molecular information within the cells, tissues, and organisms in the rock.
Since they already knew which organisms most of the fossils represented, the team was able to discover molecular fingerprints that reliably discriminate between fungi, bacteria, and other groups.
These fingerprints were then used to identify some of the more mysterious members of the Rhynie ecosystem, including two specimens of an enigmatic tubular “nematophyte”.
These strange organisms, which are found in Devonian – and later Silurian – sediments have both algal and fungal characteristics and were previously hard to place in either category. The new findings indicate that they were unlikely to have been either lichens or fungi.
Dr. Sean McMahon, Chancellor’s Fellow from the University of Edinburgh’s School of Physics and Astronomy and School of GeoSciences, said: “We have shown how a quick, non-invasive method can be used to discriminate between different lifeforms, and this opens a unique window on the diversity of early life on Earth.”
The team fed their data into a machine learning algorithm that was able to classify the different organisms, providing the potential for sorting other datasets from other fossil-bearing rocks.
The study, published in Nature Communications, was funded by The Royal Society, Wallonia–Brussels International, and the National Council of Science and Technology of Mexico.
Dr Corentin Loron, Royal Society Newton International Fellow from the University of Edinburgh’s School of Physics and Astronomy said the study shows the value of bridging paleontology with physics and chemistry to create new insights into early life.
“Our work highlights the unique scientific importance of some of Scotland’s spectacular natural heritage and provides us with a tool for studying life in trickier, more ambiguous remnants,” Dr. Loron said.
Dr. Nick Fraser, Keeper of Natural Sciences at National Museums Scotland, believes the value of museum collections for understanding our world should never be underestimated.
He said: “The continued development of analytical techniques provides new avenues to explore the past. Our new study provides one more way of peering ever deeper into the fossil record.”
Reference: “Molecular fingerprints resolve affinities of Rhynie chert organic fossils” by C. C. Loron, E. Rodriguez Dzul, P. J. Orr, A. V. Gromov, N. C. Fraser and S. McMahon, 13 March 2023, Nature Communications.
DOI: 10.1038/s41467-023-37047-1
