Ediacaran coupling of climate and biosphere dynamics

Thomas William Wong Hearing, Benjamin Tindal, Thomas M. Vandyk, Lin Na, Alexandre Pohl, Alexander G. Liu, Thomas H. P. Harvey, Mark Williams

Throughout the Phanerozoic (538.8 Ma to present), climate change is demonstrably linked to radiations, extinctions, and turnovers in the biosphere. Here, we show that this connection existed in the late Ediacaran (~579 to 538.8 Ma), the first interval in Earth’s history to host complex macro-organisms, including early metazoans. Current correlations of glacial sedimentary deposits have been used to argue for either one long (>20 Myr) or up to four short (1 to 5 Myr) ice ages during the mid- to late Ediacaran. Here, we evaluate the dating, correlation, and glaciogenicity of candidate Ediacaran glaciogenic deposits and find evidence for two icehouse intervals (mid-Ediacaran, ~593 to 579 Ma; and late Ediacaran, ~565 to ~550 Ma) alternating with greenhouse intervals (late Ediacaran, ~579 to 565 Ma; and terminal Ediacaran, ~550 Ma to Cambrian). Both icehouse intervals were characterised by high to mid-latitude glaciation of ~10 to 15 Myr duration, with expansion and retreat of ice sheets. These changes in climate state correspond in time with apparent step-changes in the late Ediacaran biosphere, including changes in standing diversity and taxonomic composition of palaeocommunities. Our results support a Phanerozoic-style coupling of global climate and biosphere during the early stages of animal evolution.