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Summary. Sulfur-cycling bacterial communities are known from the modern deep-sea off the west coast of South America. Similar fossil communities have been discovered in Paleoproterozoic sediments in Western Australia, in sediments dated at 2.3 billion years, and now, at 1.8 billion years in the Duck Creek Formation. Comparison of cellular morphology, community structure and chemical analyses in fossil and modern communities supports identification of the Duck Creek fossils as a sulfur-cycling bacterial community, and shows no evidence of evolutionary change. This is a remarkable example of stasis, and may be attributed to the physical stability of such sub-seafloor environments.
Comment. Stasis is the lack of morphological change. The authors suggest this is due to lack of environmental change, but stasis is a common feature of the fossil record. This observed fossil pattern is directly contrary to Darwin’s predictions that every geological stratum should show evidence of slow, gradual evolutionary changes. These sulfur-cycling bacteria are striking examples of the failure of Darwin’s prediction.
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