Sprigg notices impressions at the Ediacara mine

Reg Sprigg, assistant government geologist of South Australia, was assessing abandoned mine workings in the Ediacara Hills when he noticed circular and frond-like impressions on the undersides of sandstone slabs. He published them in 1947 as early Cambrian jellyfish. Both parts of that description turned out to be wrong — the fossils are Precambrian, and few of them are jellyfish — and the paper was not widely taken up at the time. Comparable fossils had in fact been found earlier in Namibia and in Charnwood Forest in England without being recognised as Precambrian, largely because the assumption that no complex life predated the Cambrian was strong enough to override the stratigraphy. The Ediacara material eventually gave its name to the Ediacaran Period, the first new period added to the geological time scale in over a century.

Historical — it happened, and the record is settled.