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posted 18. July 2005 15:27
Science, Vol 308, Issue 5718, 59-60 , 1 April 2005
The Calibration of Ediacaran Time
Alan J. Kaufman
More than a century ago, the last great geological period was formally ratified by an international committee. This was the final rocky step in the subdivision of deep time based on the evolutionary progression of animal fossils. However, recent years have seen the identification of an older and tumultuous new interval, the Ediacaran Period, during which Earth's earliest soft-bodied organisms emerged in the oceans. This interval was recently ratified (1), underscoring advances in the absolute dating (2-6) and worldwide correlation of geological strata that were deposited in isolated basins before true animals exploded onto the scene in the succeeding Cambrian Period.