440-Million-Year-Old Fossilized Fungi May Be The Oldest Land Dwellers Yet Discovered

Though not the oldest living creatures, these fungi may have paved the way for living creatures to take hold of the land

Martin R. Smith

Before the first fishy creatures stepped onto Earth’s shores, the land had to become a hospitable place for life to thrive. It took billions of years for Earth’s surface to morph from that barren wasteland. But the details of that transition recorded in the fossil record are sketchy at best. Now, researchers believe they might have found ancient tiny fungi fossil remains—creatures that could have paved the way for future life.

According to a new study published in the Botanical Journal of the Linnean Society, the fossilized fungi, called Tortotubus, lived about 440 million years ago. While it is difficult to precisely date the ancient creatures due to their tiny size and age, says Martin Smith, study author and paleontologist at Durham University, it is unlikely that the fungi are younger than the previous oldest fossil, which is roughly 5 million years younger.

These aren't necessarily the first organism to live on land, but researchers believe the fungi could be the oldest fossils of a land-living organisms yet discovered, Rachel Feltman writes for the Washington Post

Scientists believe that the first organisms to colonize the land probably began creeping out of the oceans between 500 and 450 million years ago during the Paleozoic era. Meaning that the fungi may have been among the earliest organisms to thrive on land, Brooks Hays writes for United Press International.

"During the period when this organism existed, life was almost entirely restricted to the oceans: nothing more complex than simple mossy and lichen-like plants had yet evolved on the land," Smith said in a statement. "But before there could be flowering plants or trees, or the animals that depend on them, the processes of rot and soil formation needed to be established."

By examining hundreds of the tiny fossils, Smith found that Tortotubus may have helped set the stage for future land life. The fungi's branching mycelium networks it used to feed held the soil together, allowing plants to take hold. The creature also munched on decomposing organic matter, which recycled nutrients back into the soil, Feltman reports.

At the time though, organic matter organic was likely scarce. So Smith says Tortotubus probably also fed on algae and bacteria. Even so, it's unlikely that researchers will find surviving specimens of its food.

This isn’t the first time Tortotubus specimens have been found. In fact, scientists have been examining their traces since the species was discovered in the 1980s. However, Tortotubus fossils are incredibly tiny, even smaller than a human hair. So it took scientists decades to scrounge up enough evidence to begin to understand the ancient fungi’s appearance and behavior, Becky Ferreira reports for Motherboard.

“It’s like having the individual stills from a movie,” Smith tells Ferreira. “Suddenly, there are enough of the stills that you can play the movie and you can see the developmental trajectory.”

This find shows that with just the right conditions, some amazing creatures can be preserved and just goes to show that many more may still be out there waiting to be found. "I’ll certainly be keeping my eyes peeled, looking at older rocks, now that we’ve pushed the fossil record back further," Smith tells Feltman. 

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