Researchers working in the shale beds of Arctic Canada have made a discovery that seems to change drastically how old multicellular life on land is. The team has discovered a fossil of an ancient fungus that pushes the earliest evidence of life back more than half a billion years. The microscopic fossils are newly dated and date to between 900 million and 1 billion years ago.
If the analysis holds up to scrutiny, the discovery means that the first multicellular life on land was alive much earlier than previously thought. Before the discovery, the oldest uncontested fungus fossil was a 407 million-year-old specimen found in Scotland.
The new fungus fossil was found in the Grassy Bay Formation and is named Ourasphaira giraldae and is said to be surprisingly well preserved and intricate. During the study of the new fossil, the team was able to make out multicellular, branching, separate filaments that have bulbous spheres on the ends. These structures make up the mycelium of a fungus.
Using a tool called Fourier-transform infrared spectroscopy the team confirmed the presence of chitin, which is a compound found in the cell walls of fungi. Additional study using transmission electron microscopy revealed a bilayered cell wall structure. Scientists know that fungus was around when the first plants began to emerge 500-600 million years ago.
However, the fungus molecular clock suggested the life forms should have been around sooner. The molecular clock is the mutation rate of biomolecules in DNA that are used to determine the history of an organism. The DNA of fungus indicated that it had made its first appearance a billion years ago. The discovery of the new fossil helps to confirm that timeline. Further study into the fungus is ongoing.