Knoll, AndrewBarghoorn, Elso S.2009-06-231977Knoll, Andrew H., and Elso S. Barghoorn. 1977. Archean microfossils showing cell division from the Swaziland system of South Africa. Science 198(4315): 396-398.0036-8075http://nrs.harvard.edu/urn-3:HUL.InstRepos:3119532A newly discovered population of organic walled microstructures from the Swaziland System, South Africa, is considered to be biological on the following grounds: (i) the structures are carbonaceous and occasionally have internal organic contents; (ii) the population has a narrow unimodal size frequency distribution (average diameter, 2.5 micrometers; range, 1 to 4 micrometers); (iii) the structures are not strictly spherical, but are commonly flattened and folded like younger microfossils; (iv) the sedimentary context is consistent with biogenic origins; and (v) various stages of binary division are clearly preserved.en-US10.1126/science.198.4315.396