A team of scientists from Virginia Tech, the Chinese Academy of Sciences, Guizhou University of Education and the University of Cincinnati have discovered the remains of a fungus-like microfossil that emerged at the end of an ice age about 635 million years ago. years. It is the oldest land fossil ever found. It is three times older than the dinosaurs.
What role have fungi played throughout Earth’s history? More decisive than we thought, because this new discovery of a species similar to a fungus, places the emergence of this kingdom much earlier than we believed and, according to experts, could have helped the Earth to recover from an ice age, since provide direct fossil evidence of land colonization by fungi during the Ediacaran period in China.
The earliest evidence of life on our planet
The fossil in question is made up of thread-like filaments, attached to hollow spheres in 635-million-year-old rocks that may also help explain how life recovered from “Snowball Earth” , the periods in which it was so cold that even much of the equator was covered in ice.
“It was an accidental discovery,” said Tian Gan, a co-author of the paper published in the journal Nature. “At that point, we realized that this could be the fossil that scientists have been looking for for a long time. If our interpretation is correct, it will be helpful in understanding paleoclimate change and the early evolution of life .”
These filaments bear a strong resemblance to modern mushrooms, and the authors think that is probably what they were: mushrooms. However, wherever this species fits into the tree of life, Gan thinks it can explain one of the great questions of paleontology: how did life rebound so quickly after being nearly wiped out by “Snowball Earth” or superglaciation ?.
In this event that unfolded about 717 million years ago, the average temperatures reached fifty degrees below zero and the ice from the poles extended to the equator.
The microfossils found in the Doushantuo Formation are pyritized but contain traces of organic matter . They include branched filaments of two morphological types and associated hollow spheres. Filaments are at least hundreds of microns long and can be straight, curved, or bent. Their analysis indicated that they likely represent fungal microorganisms that colonized karst environments sometime between 635 and 632 million years ago and that they played a key role in catalyzing atmospheric oxygenation and biospheric evolution after the catastrophic “Earth Ball” event. snow”.
Until now it had been a mystery
The Earth recovered and produced a larger and more complex biosphere than before, which has been a mystery to scientists, but the new fossil may finally solve this puzzle.
Along with other terrestrial microbes, this organism had the ability to accelerate the chemical climate and release phosphorus into the oceans, which would have stimulated marine bioproductivity. T he researchers believe that the microorganism helped therefore to recondition the environment using its formidable digestive system.
Fungi have digestive systems capable of recycling vital nutrients and can chemically break down rocks and other hard matter using enzymes secreted into the environment; all of this can be recycled and exported to the ocean.
“Due to their connection to land plants and important nutritional cycles, land fungi have a driving influence on biochemical weathering, the global biogeochemical cycle, and ecological interactions,” Gan clarifies.
Previous work has suggested that land plants and fungi formed a symbiotic relationship about 400 million years ago, but the new fossil rewrites the timeline to 635 million years ago. Did fungi exist before land plants? Based on this finding, the answer appears to be “yes.”
“Our study suggests that it is. Our fungus-like fossil is 240 million years older than the previous record. This is, so far, the oldest record of terrestrial fungi,” concludes the expert.
Referencia: Tian Gan, Taiyi Luo, Ke Pang, Chuanming Zhou, Guanghong Zhou, Bin Wan, Gang Li, Qiru Yi, Andrew D. Czaja, Shuhai Xiao. Cryptic terrestrial fungus-like fossils of the early Ediacaran Period. Nature Communications, 2021 ; 12 (1) DOI: 10.1038/s41467-021-20975-1
