Integrated records of environmental change and evolution challenge the Cambrian Explosion

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The ‘Cambrian Explosion’ describes the rapid increase in animal diversity and abundance, as manifest in the fossil record, between ~540 and 520 million years ago (Ma). This event, however, is nested within a far more ancient record of macrofossils extending at least into the late Ediacaran at ~571 Ma. The evolutionary events documented during the Ediacaran–Cambrian interval coincide with geochemical evidence for the modernisation of Earth’s biogeochemical cycles. Holistic integration of fossil and geochemical records leads us to challenge the notion that the Ediacaran and Cambrian worlds were markedly distinct, and places biotic and environmental change within a longer-term narrative. We propose that the evolution of metazoans may have been facilitated by a series of dynamic and global changes in redox conditions and nutrient supply, which, potentially together with biotic feedbacks, enabled turnover events that sustained multiple phases of radiation. We argue that early metazoan diversification should be recast as a series of successive, transitional radiations that extended from the late Ediacaran and continued through the early Palaeozoic. We conclude that while the Cambrian Explosion represents a radiation of crown-group bilaterians, it was simply one phase amongst several metazoan radiations, some older and some younger.

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Fig. 1: Integrated geochemical and biotic record between 670 and 480 million years ago.
Fig. 2: Key transitional Ediacaran and Cambrian taxa.

A. Fedorov (d); S. Xiao (e)

Fig. 3: Ediacaran ecosystem dioramas.
Fig. 4: Biotic evolution across the Ediacaran–Cambrian.

Change history

  • 12 April 2019

    In the version of this article initially published, the reference “Mitchell, E. G., & Kenchington, C. G. The utility of height for the Ediacaran organisms of Mistaken Point. Nat. Ecol. Evol. 2, 1218–1222 (2018).” was missing. A callout to the reference should have been placed at the end of this sentence: “For biotic replacement to occur, taxa must be both spatially collocated and have similar resource requirements, yet spatial analyses of contemporary communities find only very limited instances of resource competition.” The reference has been added to the list, and the error has been corrected in the PDF and HTML versions of the article.


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This work was funded by the following Natural Environment Research Council (NERC) Grants: NE/P013643/1 (BETR Collaboration Grant to R.W. and A.L.), NE/L002558/1 (E3 DTP studentship to F.B.), NE/L002434/1 (GW4+ DTP studentship to F.D.), NE/L011409/2 (Independent Research Fellowship to A.L.), NE/P002412/1 (E.G.M.), NEE3849S (NERC-BGS project support to P.R.W.). Funding also came from a Leverhulme Early Career Fellowship and Isaac Newton Trust Early Career Fellowship to C.G.K.; a Henslow Research Fellowship from Cambridge Philosophical Society to E.G.M.; and a School of GeoSciences studentship to A.P.

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All authors were involved in conceiving the work. F.B., A.L., J.H.C., E.G.M., C.G.K., F.D. and A.P. collated data for figures. R.W. co-ordinated the work, and all authors wrote the paper.

Correspondence to Rachel Wood.

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Supplementary Information

Supplementary Figure 1 and Supplementary Tables 1 and 2 (Fossil key and occurrence catalogue for Fig. 3 and 4).

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Wood, R., Liu, A.G., Bowyer, F. et al. Integrated records of environmental change and evolution challenge the Cambrian Explosion. Nat Ecol Evol 3, 528–538 (2019) doi:10.1038/s41559-019-0821-6

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