The latest study led by geologist Gregory Retallack of University of Oregon has presented the evidence for life on the earth, which dates back to 2.2 billion years, back. The team of Retallack in their study has mentioned about the 2.2 billion year old fossils of size of about the match stick head, which were connected in bunches by threads. The fossil was discovered from the ancient soil of South Africa and has been named Diskagma Buttonii, which means disc-shaped fragments of Andy Button.
To verify and document and verify that the Diskagma buttonii was a fossil, X-ray imaging was performed. As a result of the X-ray imaging the researchers described the fossils as the strange, little hollow urn-shaped structures with a terminal cup and basal attachment tube.
Diskagma Buttonii fossils bear resemblance with three living organisms of present time. The organisms are:
• Leocarpus fragilis found in Oregon's Three Sisters Wilderness
• Lichen Cladonia Ecmocyna gathered near Fishtrap Lake in Montana
• Fungus Geosiphon pyriformis from near Darmstadt, Germany
It is also similar to the 2.8 billion year old Thucomyces lichenoides fossil in morphology and size. The Thucomyces lichenoides were also discovered in South Africa. The two fossils can be differentiated just with the chemical composition of each-other, which is completely different.
The discovered fossil is four times as old as the previous fossilized evidence of land life, and nearly half as old as Earth itself. At present, it is unclear that what exactly the discovered fossils are as the ancient fossil resembles with the modern soil organism called Geosiphan. Geosiphan is a fungus with a central cavity filled with symbiotic Cyanobacteria. At present, a 0.3 to 1.8 mm long fossil represents the benchmark for the age of the land dwelling known fossil.
Fossil soils that act as the host of the fossils are considered as evidence that marks for the rise of the amount of oxygen in the atmosphere at about 2.4 billion to 2.2 billion years ago. This is widely referred as the Great Oxidation Event. And at the time, when the latest discovered fossil, Diskagma Buttonii existed the air on earth rose about 5 percent oxygen, which is comparatively lower than the 21 percent oxygen content of present time. But, before the Great Oxidation Event, there hardly existed any oxygen on earth.
The researchers believe that the fossils are the only promising candidate that supports the existence of the oldest known eukaryote. These were the organisms with cells that contained complex structures, and had a nucleus, within membranes.
The research was published in a journal Precambrian Research.