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Nat Ecol Evol. 2019 Apr;3(4):577-581. doi: 10.1038/s41559-019-0806-5. Epub 2019 Mar 4.

Putative sponge biomarkers in unicellular Rhizaria question an early rise of animals.

Author information

1
Max Planck Institute for Biogeochemistry, Jena, Germany. benjamin.nettersheim@bgc-jena.mpg.de.
2
MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany. benjamin.nettersheim@bgc-jena.mpg.de.
3
Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia.
4
Department of Plant Biology, Uppsala BioCentre Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
5
Institute of Microbiology, University of Innsbruck, Innsbruck, Austria.
6
Adaptation and Diversity in Marine Environment (AD2M), Laboratory Ecology of Marine Plankton team Station Biologique de Roscoff, Sorbonne Université, CNRS, UMR7144, Roscoff, France.
7
Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, USA.
8
MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany.
9
Max Planck Institute for Chemistry, Mainz, Germany.
10
Department of Biology, Heinrich-Heine-Universität Düsseldorf, Dusseldorf, Germany.
11
Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland.
12
Wadsworth Center, New York State Department of Health, Albany, NY, USA.
13
Leibniz Centre for Tropical Marine Research (ZMT), Biogeochemistry and Geology, Bremen, Germany.
14
Max Planck Institute for Biogeochemistry, Jena, Germany. challmann@bgc-jena.mpg.de.
15
MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany. challmann@bgc-jena.mpg.de.

Abstract

The dawn of animals remains one of the most mysterious milestones in the evolution of life. The fossil lipids 24-isopropylcholestane and 26-methylstigmastane are considered diagnostic for demosponges-arguably the oldest group of living animals. The widespread occurrence and high relative abundance of these biomarkers in Ediacaran sediments from 635-541 million years (Myr) ago have been viewed as evidence for the rise of animals to ecological importance approximately 100 Myr before their rapid Cambrian radiation. Here we show that the biosynthesis of 24-isopropylcholestane and 26-methylstigmastane precursors is common among early-branching unicellular Rhizaria-heterotrophic protists that play an important role in trophic cycling and carbon export in the modern ocean. Negating these hydrocarbons as sponge biomarkers, our study places the oldest evidence for animals closer to the Cambrian Explosion. Cambrian silica hexactine spicules that are approximately 535 Myr old now represent the oldest diagnostic sponge remains, whereas approximately 558-Myr-old Dickinsonia and Kimberella (Ediacara biota) provide the most reliable evidence for the emergence of animals. The proliferation of predatory protists may have been responsible for much of the ecological changes during the late Neoproterozoic, including the rise of algae, the establishment of complex trophic relationships and the oxygenation of shallow-water habitats required for the subsequent ascent of macroscopic animals.

PMID:
30833757
DOI:
10.1038/s41559-019-0806-5
[Indexed for MEDLINE]

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