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Published October 1, 2018 | public
Journal Article

Life in changing fluids: A critical appraisal of swimming animals before the Cambrian

Gold, David ORCID icon

Abstract

Molecular and fossil data place the initial diversification of animals in the Neoproterozoic, though there remains too much enough uncertainty to produce an exact chronology. This is unfortunate, as the Neoproterozoic represents a period of intense climate change, including multiple global glaciation events as well changes to ocean chemistry and oxygen content. Several authors have suggested that the coevolution of animals and their environment was tightly coupled, but such hypotheses rest on the presence of swimming (pelagic) species. In this paper, I review the evidence for pelagic animals during the Neoproterozoic. I conclude that there are very few groups of planktotrophic swimming animals that were likely to have existed at this time, with the possible exception of medusozoan cnidarians (jellyfish). Ultimately, hypotheses connecting Earth and animal evolution in the Neoproterozoic need to be tested with more geochemical work, fossil discoveries, and refinement of molecular clocks targeted on the relevant groups.

Additional Information

© The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. Published: 03 May 2018.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023