These tiny, strange fossils are the oldest of any land-based organism

At first glance, they do not look like much: tiny fragments of a primordial fungus shorter than a single hair’s width. But these fungal remnants possess the unique distinction of being the oldest-known fossils of any land-dwelling organism.

A study published on Wednesday described microfossils of a subterranean fungus called Tortotubus that was an early landlubber at a time when life was largely confined to the seas, including samples from Libya and Chad that were 440 to 445 million years old.

The fossils represented the root-like filaments that fungi use to extract nutrients from soil. Tortotubus possessed a cord-like structure similar to some modern fungi. It was unclear whether it produced mushrooms.

Tortotubus helped set the stage for complex land plants and later animals by triggering the process of rot and soil formation.

“By building up deeper, richer, more stable soils, Tortotubus would have paved the way for larger, more complex green plants to quite literally take root, in turn providing a food source for animals and allowing the escalation of terrestrial ecosystems,” said paleontologist Martin Smith of Britain’s Durham University, who conducted the research while at the University of Cambridge.

These fossils, also discovered in other places including Sweden, Scotland and New York state, reflect the humble beginnings of life on the land.