More than half-a-billion years ago, ancient terrestrial fungus may have helped Earth recover from a catastrophic ice age.
The oldest evidence of land fungus may be a wee microfossil that’s 635 million years old, found in a cave in southern China. Too small to be seen with the naked eye, this remarkable find pushes back the appearance of terrestrial fungus by about 240 million years to a period known as « snowball Earth » when the planet was locked in ice from 750 million to 580 million years ago. The presence of land fungus at this critical point may have helped Earth to transition from a frozen ice ball to a planet with a variety of ecosystems that could host diverse life-forms, scientists wrote in a new study. By breaking down minerals and organic matter and recycling nutrients into the atmosphere and ocean, ancient fungus could have played an important part in reshaping Earth’s geochemistry, creating more hospitable conditions that paved the way for terrestrial plants and animals to eventually emerge and thrive. Related: Images: The oldest fossils on Earth Scientists discovered the fossilized threadlike filaments — a trademark of fungus structures — in sedimentary rocks from China’s Doushantuo Formation in Guizhou Province, dating to the Ediacaran period (about 635 million to 541 million years ago). Identifying rocks that might contain microscopic fossils takes luck as well as skill, said study co-author Shuhai Xiao, a professor of geosciences with the Virginia Tech College of Science (VT) in Blacksburgh, Virginia. « There’s an element of serendipity, but there’s also an element of experience and expectation. Having worked with microfossils, one knows what kind of rocks to look at, » Xiao told Live Science. For example, rocks must be fine-grained, because the fossils are so small. Color can also provide clues; organic carbon in microfossils can make fossil-bearing rocks look darker than rocks that don’t contain fossils.
