Paleontologists Find 635-Million-Year-Old Land Fungus-Like Fossils
The 635-million-year-old pyritized fungus-like microfossils found in the Ediacaran-period Doushantuo Formation in China provide direct fossil evidence for the colonization of land by fungi.
The Ediacaran-period fungus-like fossils were found in small cavities within well-studied sedimentary dolostone rocks of the Doushantuo Formation at Weng’an, South China.
“It was an accidental discovery. At that moment, we realized that this could be the fossil that scientists have been looking for a long time,” said Tian Gan, a Ph.D. student at the Virginia Tech.
“If our interpretation is correct, it will be helpful for understanding the paleoclimate change and early life evolution.”
The Doushantuo microfossils are pyritized but contain trace amount of organic matter.
They include branching filaments of two morphological types and associated hollow spheres.
The filaments are hundreds of microns in length at the minimum, and can be straight, curved, or bent.
The team’s analysis indicates that they likely represent fungal microorganisms that colonized karstic environments sometime between 635 and 632 million years ago.
They may have played a role in catalyzing atmospheric oxygenation and biospheric evolution in the aftermath of the catastrophic ‘snowball Earth’ event.
“About 635 million years ago, when the Ediacaran period began, our planet was recovering from the Cryogenian global glaciation,” the researchers said.
“At that time, ocean surfaces were frozen to a depth of more than a kilometer and it was an incredibly harsh environment for virtually any living organism, except for some microscopic life that managed to thrive.”
“Scientists have long wondered how life ever returned to normalcy and how the biosphere was able to grow larger and more complex than ever before.”
“With this new fossil in hand, we are certain that these microscopic, low profile cave dwellers played numerous roles in the reconditioning of the terrestrial environment in the Ediacaran time.”
Although previous evidence stated that terrestrial plants and fungi formed a symbiotic relationship around 400 million years ago, the team’s discovery recalibrates the timeline of when these two kingdoms colonized the land.
“The question used to be: ‘Were there fungi in the terrestrial realm before the rise of terrestrial plants?’,” said Professor Shuhai Xiao, also from the Virginia Tech.
“And I think our study suggests yes. Our fungus-like fossil is 240 million years older than the previous record. This is, thus far, the oldest record of terrestrial fungi.”
The discovery is reported in a paper in the journal Nature Communications.
T. Gan et al. 2021. Cryptic terrestrial fungus-like fossils of the early Ediacaran Period. Nat Commun 12, 641; doi: 10.1038/s41467-021-20975-1