450 million years later, he is back!

When a researcher discovers “ fool's gold », he is generally disappointed. This nickname is the one given to pyrite, a mineral composed of shiny iron sulfide and a golden yellow color which often causes it to be confused with real gold. But for the team of Professor Luke Parry from the University of Oxford, this pyrite was found to be more valuable than gold itself : it made it possible to preserve a unique specimen called Lomankus edgecombeian ancestral arthropod close to modern-day spiders and scorpions. The results of their research were published October 29 in the journal Current Biology.

A miraculous preservation

This discovery is exceptional because ancient arthropods, made primarily of soft tissue, usually decompose within a few days of death. However, the specimen discovered by Parry's team benefited from a unique chemical combination.

The simultaneous presence organic matter, iron and the absence of oxygen allowed its fossilization in pyrite. The iron atoms were able to replace the atoms of the body, thus creating a mineralized, and therefore more solid, replica of the soft tissues. The absence of oxygen slowed or even stopped the bacterial decay process, giving minerals time to properly penetrate and replace the tissues. Finally, the presence of organic matter, such as complex carbon-based molecules, could promote the formation of organometallic compounds, thus reinforcing the conservation of the Lomankus edgecombei.

« We obtain an almost complete vision of their anatomy », enthuses Parry, highlighting the rarity of such preservation. Why such excitement about such an ancient animal? Parry explains: “ Fossils like this tell us a lot about what life looked like on Earth hundreds of millions of years ago ».

A 450-million-year-old “organic Swiss army knife”

The Lomankus presents a fascinating feature : its frontal appendages, equipped with small pincers and three long flexible flagella, probably served it to explore its environment. They suggest that this arthropod had a unique strategy for exploring its environment, different from what can be observed in other species.

This adaptation, coupled with the absence of eyes, certainly proves that Lomankus lived in the dark depths of the primitive oceans. Indeed, the ocean depths are completely deprived of sunlight. It therefore did not need this organ to detect its food or its predators.

These multifunctional appendages perhaps foreshadow the remarkable diversity of today's arthropods, a group which today includes the largest number of species on Earth. The latter brings together more than a million identified species. Some scientists even put forward much higher figures, up to several million ! You have all already encountered them at least once: butterflies, bees, ladybugs or dragonflies or even eaten them. Shrimp and crabs are also in this group.

A fossil site which has not revealed all its secrets

The discovery site, located in New York State, fis one of the rare deposits in the world where fossilization by pyrite is observedalongside the German Hunsrück Slate and the Chinese Chengjiang Biota. It is already famous for its trilobites, but the discovery of Lomankus suggests other discoveries, also exceptional. In addition, this type of deposit often surprises scientists by revealing organisms with strange and unexpected morphologies. “ This fossil suggests that many other discoveries await us at this site “, says Parry.

These deposits therefore act as real time capsulescapable of preserving specimens in excellent conditions, which allows researchers to have valuable information on paleobiodiversity and past ecosystems. The data obtained from these deposits also make it possible to test the most recent evolutionary theories and to better understand the mechanisms that led to the diversification of life on our planet. A certain Charles Darwin would certainly have been delighted to know of their existence; unfortunately, he will never have seen the color.

• Researchers have discovered a rare arthropod fossil, the Lomankus edgecombeipreserved in pyrite, 450 million years old.
• The specimen has unique appendages and lived in the lightless depths of the sea, suggesting an exploration strategy distinct from today's arthropods.
• This fossil deposit in New York, where the pyrite allows exceptional preservation, could still reveal many similar discoveries.

???? To not miss any news from Presse-citron, follow us on Google News and WhatsApp.