The microscopic, inconspicuous cave dweller played a huge role in our planet’s recovery from a catastrophic Ice Age.
When you think of mold, you might think of those black spots in the corner of your bathroom, or the rotting fruit in your green container. But that’s not all. A new study shows that fungi have played a very important role in the history of the earth. They would even have helped our planet recover from a harsh Ice Age.
Oldest terrestrial fossil
A team of researchers has discovered the remains of a fungus-like organism that emerged about 635 million years ago towards the end of the Ice Age. It’s a special find. Which turns out to be the oldest terrestrial fossil ever found. To put that in perspective, this microscopic fossil is about three times older than the oldest dinosaur found.
The discovery
The unusual fossil was found in small hollows in the well-studied sedimentary layers of the Chinese Doushantuo Formation. Here, the researchers came across a few long, thread-like filaments – one of the most important features of fungi. “It was an accidental discovery,” says researcher Tian Gan. “It was then that we realized that this might be the fossil that scientists had been looking for for a long time.”
The 635 million year old fungus-like organism. Image: Andrew Czaja of University of Cincinnati
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The discovery of the ancient fungus-like organism may be key to understanding multiple turning points in Earth’s history, including that during the Ediacarium (the era between 635 and 541 million years ago). When the Ediacarium began, the planet was recovering from a catastrophic Ice Age, also known as Snowball Earth. At the time, the ocean surfaces were frozen to a depth of more than a kilometer. It was an incredibly harsh environment for almost any living organism, except for some microscopic life that managed to thrive. Scientists have long wondered how life ever returned to normal – and how the biosphere could get bigger and more complex than ever before.
Recovery
But now the researchers are coming to the conclusion that the newly discovered fossil may be able to answer that pressing question. The researchers are sure that this microscopic, inconspicuous cave dweller has helped to make snowball Earth habitable again. How? Partly because of its formidable digestive system.
Digestive system
Fungi have a fairly unique digestive system that plays an even greater role in the cycle of vital nutrients. With the help of enzymes excreted into the environment, terrestrial fungi can chemically break down rocks and other hard organic matter. This can then be recycled and transported to the ocean. “Fungi have a mutualistic relationship (a relationship between two organisms that is beneficial for both, ed.) With the roots of plants,” Gan explains. “Because of their relationship with land plants and important feeding cycles, terrestrial fungi influence biochemical weathering, the global ecological cycle and other ecological interactions.”
More about fungi
Fungi are among the first organisms to lay the foundation for the very first forms of life that began to colonize the land. Although only five percent of the fungi species on Earth have been discovered, we know that their function is very important. Fungi, for example, play an important ecological role in the breakdown of dead organic material. They then bring new nutrients into the ecosystem from this dead plant material.
In addition, the study also sheds a glimpse into the emergence of the first terrestrial fungi. “The question used to be: were there fungi on the land before the emergence of terrestrial plants?” researcher Shuhai Xiao wonders. “And I think our study suggests that the answer to that question should be yes. Our fungus-like fossil is 240 million years older than the previous record holder. This is the oldest terrestrial fungus ever discovered so far. ”
Fossilization
The discovery of the 635 million year old fungus-like organism is therefore very special. Sixty years ago, few people believed that microorganisms, such as bacteria and fungi, were preserved as fossils. But now that Xiao has seen them with his own eyes, he plans to learn more about how they could fossilize. “It’s always important to understand organisms in the context of the environment,” he explains. “We have a general idea that they lived in small hollows. But little is known about exactly how they lived and how they have been preserved. ”
The researchers are therefore enthusiastically continuing their research. Because although there are various indications that the discovered fossil belongs to the fungi, they cannot yet prove this completely. Further research into the microfossils is therefore in full swing. “If our interpretation is correct, this fossil could be extremely useful for understanding past climate change and the evolution of early life forms,” Gan concludes.
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