Several microscopic fungi fossils dating back 900 to 1000 million years have been discovered by an international team of scientists in the Northwest Territories of Canada.
This discovery push back, according to the researchers, the appearance of fungi on Earth half a billion years since the oldest known to date were 400 to 450 million years during the Ordovician period.
The discovered specimens are organic-walled microfossils Ourasphaira giraldae. They were trapped in solidified mud from the estuarine shales of the Grassy Bay Formation, south of Victoria Island, which prevented oxygen from infiltrating and decomposing the fossils.
Because of their exceptional state of preservation, the organisms still possessed the characteristic morphology of the fungi and still bore traces of chitin, a substance that makes up their cell wall.
“Fungi are essential components of today’s ecosystems and are among the first forms of life to colonize the continents,” says Corentin Loron, University of Liège.
The fact that Urasphaira giraldae has been preserved in shallow estuarine shale suggests that this fungus may have lived in an estuarine environment. It could have been transported in this environment from terrestrial or marine niches.
Nowadays, fungi are mostly terrestrial, although some marine forms exist.
The subsequent colonization of terrestrial environments by fungi may have preceded and favored the colonization of land by plants by symbiosis and soil treatment, which would have provided ecological niches, say the authors of these works published in the journal Nature.
Moreover, the existence of these organisms at this time of the geological evolution of our planet also removes the origins of opisthocontes, this eukaryotic crown group which also includes animals.
This discovery, which was led by Elizabeth C. Turner, a paleobiologist from Laurentian University in Ontario, suggests that other fungi and eukaryotes will be unearthed in the coming years and will provide insights into the evolution of ancient terrestrial biosphere