Algal origin of sponge sterane biomarkers negates the oldest evidence for animals in the rock record
Abstract
The earliest fossils of animal-like organisms occur in Ediacaran rocks that are approximately 571 million years old. Yet 24-isopropylcholestanes and other C₃₀ fossil sterol molecules have been suggested to reflect an important ecological role of demosponges as the first abundant animals by the end of the Cryogenian period (>635 million years ago). Here, we demonstrate that C₃₀ 24-isopropylcholestane is not diagnostic for sponges and probably formed in Neoproterozoic sediments through the geological methylation of C₂₉ sterols of chlorophyte algae, the dominant eukaryotes at that time. These findings reconcile biomarker evidence with the geological record and revert the oldest evidence for animals back into the latest Ediacaran.
Additional Information
© 2020 Nature Publishing Group. Received 27 April 2020; Accepted 23 September 2020; Published 23 November 2020. The study was funded by the Australian Research Council grants DP160100607 and DP170100556 (to J.J.B.). I.B. gratefully acknowledges the Texaco Postdoctoral Fellowship. The authors are grateful to L. M. van Maldegem, P. Adam and P. Schaeffer for their helpful feedback. Data availability: All data that support the paper are presented in the main text of the manuscript and in the Supplementary Information. Author Contributions: I.B. conceived the study, performed the analyses and wrote the first draft. J.M.H. and J.K.V. helped with compound identification. I.B. and B.J.N. interpreted the data. I.B., J.M.H., B.J.N., J.K.V., C.H. and J.J.B. prepared the manuscript. The authors declare no competing interests.Attached Files
Supplemental Material - 41559_2020_1334_Fig2_ESM.webp
Supplemental Material - 41559_2020_1334_MOESM1_ESM.pdf
Supplemental Material - 41559_2020_1334_MOESM2_ESM.pdf
Supplemental Material - 41559_2020_1334_MOESM3_ESM.xlsx
Files
Additional details
- Eprint ID
- 106779
- Resolver ID
- CaltechAUTHORS:20201123-100253164
- DP160100607
- Australian Research Council
- DP170100556
- Australian Research Council
- Texaco Postdoctoral Fellowship
- Created
-
2020-11-23Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field