Nature 274, 676 - 678 (17 August 1978); doi:10.1038/274676a0

A new microfossil assemblage from the Archaean of Western Australia

J. S. R. DUNLOP^*, V. A. MILNE^*, D. I. GROVES^* & M. D. MUIR^†

^*Department of Geology, University of Western Australia, Nedlands, Western Australia 6009
^†Bureau of Mineral Resources, Box 378, Canberra, A.C.T, Australia 2701

THE oldest documented microfossils are from the 3,300 Myr BP Onverwacht Group of South Africa⁶⁻⁸. Here, we discuss the occurrence of a new assemblage of microfossils from a 3,500 Myr BP silicified shallow-water to supratidal carbonate sequence of the Warrawoona Group at North Pole, Western Australia. Five morphologies of carbonaceous spheroids are recognised, including some with splits, some with tetragonal tetrad form and others with groups of up to four individuals. Their morphology is very similar to microfossils from the Onverwacht group of South Africa, and statistical tests of size distribution support a biogenic origin. This occurrence suggests that evidence for early Archaean life may be more widespread than generally thought.

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