THE BIOTIC RESPONSE TO NEOPROTEROZOIC SNOWBALL EARTH

Abstract

The commonly held notion among earth scientists that Neoproterozoic low latitude glaciation (ca. 720-585 Ma), sometimes referred to as snowball Earth, caused major extinctions and imparted important evolutionary consequences upon the biosphere is not supported by the microfossil record. In particular, silicified microfossils from pre- and syn-glacial units in the Death Valley region, California, reveal little change during the glacial interval; in fact, the syn-glacial microbiota is slightly more diverse and contains more putative autotrophic and heterotrophic eukaryotes than underlying strata. In Australia, pre- and post-glacial acritarch assemblages from shale reveal no change in diversity across the glacial interval. In modern glacial environments, productive and diverse modern microbial communities live within and upon sea and glacial ice and may provide an analogue for a more robust snowball Earth biosphere than previously considered. © 2005 Elsevier B.V. All rights reserved.