COURTESY NORA NOFFKE
EDITOR'S CHOICE IN EVOLUTION/GEOBIOLOGY
N. Noffke et al., “Microbially induced sedimentary structures recording an ancient ecosystem in the ca. 3.48 billion-year-old Dresser Formation, Pilbara, Western Australia,” Astrobiology, 13:1103-24, 2013.
Modern microorganisms leave traces on substrates called microbially induced sedimentary structures (MISS)—textures that arise from a biofilm or microbial mat interacting with the dynamics of the sediments upon which it forms. Until recently, the oldest fossilized MISS, located in South Africa, dated back to 3.2 billion years ago. However, evidence from microfossils and stromatolites, another rock structure shaped by bacteria, suggests that microbes existed at least 200 million years earlier.
In the Dresser Formation in Western Australia—one of the only places in the world with well-preserved 3.48-billion-year-old rocks—Nora Noffke...