Two years ago a group of scientists led by Allen Nutman claimed to have found supposed 3.7 billion-year-old fossils in Greenland. But recent studies and analysis of a new team of scientists have seemed to prove that this may just be a pile of rocks.
This was a very important discovery because it drove the origins of the oldest evidence of life on Earth even further. The fossils found in Greenland hinted the presence of microbial life in rock samples. And it pushes the age of the oldest stromatolite from around 3.45 billion years to 3.7 billion years.
The new team discovery
Stromatolites are layered mounds built by communities of microbes in shallow water. The rocks found in Greenland were cone-shaped distortions of rock layers, and based on different characteristics Nutman’s team concluded they were stromatolites. This kind of formations were common billion of years ago when microbes ruled the Earth, so the discovery seemed to belong to that time.
The new team of scientists doing the tests on the Greenland find is led by NASA’s astrobiologist Abigail Allwood. It’s important to know that she was part of the group that discovered the Australian stromatolites accepted as the oldest evidence of life right now. She studied the shape of Greenland’s rocks with a three-dimensional examination. This allowed her to be able to analyze the shape of the rock features and not just the surface of it.
This new point of view of the research seemed to be hinting that the features of the ‘stromatolites’ were created by intense pressure between rocks. This pressure squeezed and twisted the stone into bizarre forms. Nutman’s team worked with the face of the rock outcrop, while Allwood’s team sawed out a block to do the three-dimensional study.
Stromatolites are expected to form round cones, domes, or pillars. But when the block from the rock was sawed, what looked like a cone to Nutman turned out to be more ridge-shaped. The asymmetric bumps that stretch out in one direction are common when a tectonic force squeezes a rock layer horizontally, wrinkling it up. And stromatolites definitely don’t have that kind of shape.
Conclusions
The test ran by Allwood’s team showed that the rocks found in Greenland don’t have the distinctive lamination layer pattern expected from microorganism fossils. The explanation stating that the stones Nutman’s team found have been through a great amount of tectonic abuse since they were fresh-faced sediments, seems to be the one fitting all the new data.
“This is a classic comparing apples and oranges scenario, leading to the inevitable outcome that ours and their observations do not exactly match” stated Nutman according to the Associated Press.
Basically, there are a number of geological explanations for the structures that don’t involve living organisms. Nutman’s team is objecting these conclusions, stating that Allwood’s team analyzed the wrong samples of the fossils. But this being science, sooner or later someone is going to prove which statement is right. We just have to wait and see what further analysis may conclude.
Source: ARSTECHNICA