Scientists probing a newly exposed, formerly snow-covered outcropping in Greenland claim they have discovered the oldest fossils ever seen, the remnants of microbial mats that lived 3.7 billion years ago.
[Lucy, our hominid cousin, may have died in a tragic fall from a tree] Claims about evidence for ancient life have invariably been controversial.
The multiple lines of evidence for the Greenland stromatolites "are not as clear cut as you’d ideally want for such an extraordinary claim," cautioned Abigail Allwood, a geologist at the NASA Jet Propulsion Laboratory who has studied fossil stromatolites.
William Schopf, a pioneering paleobiologist at the University of California at Los Angeles who was not involved in the discovery.
A 3.7-billion-year-old rock with signs of associated life: Analysis of ancient rocks shows evidence of conical stromatolite-like structures (outlines indicated by dotted black lines) that are possible hallmarks of bacterial activity. (Allen Nutman) [Scientists suggest a new, earth-shaking twist on the demise of the dinosaurs] Schopf, who in 1993 reported the discovery of 3.465-billion-year-old microfossils in Western Australia, said he expects scientists to find more Greenland stromatolites as the warming atmosphere continues to melt the huge ice sheet covering the world's largest island.
[Life on Earth may have started around deep-sea hydrothermal vents] “Stromatolites are really complex, so you have to have a lot of evolution from when life started to when stromatolites appeared in the fossil record.