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Fossil steroids record the appearance of Demospongiae during the Cryogenian period

Love, Gordon D. and Grosjean, Emmanuelle and Stalvies, Charlotte and Fike, David A. and Grotzinger, John P. and Bradley, Alexander S. and Kelly, Amy E. and Bhatia, Maya and Meredith, William and Snape, Colin E. and Bowring, Samuel A. and Condon, Daniel J. and Summons, Roger E. (2009) Fossil steroids record the appearance of Demospongiae during the Cryogenian period. Nature, 457 (7230). pp. 718-722. ISSN 0028-0836.

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The Neoproterozoic era (1,000–542 Myr ago) was an era of climatic extremes and biological evolutionary developments culminating in the emergence of animals (Metazoa) and new ecosystems. Here we show that abundant sedimentary 24-isopropylcholestanes, the hydrocarbon remains of C30 sterols produced by marine demosponges, record the presence of Metazoa in the geological record before the end of the Marinoan glaciation (635 Myr ago). These sterane biomarkers are abundant in all formations of the Huqf Supergroup, South Oman Salt Basin, and, based on a new high-precision geochronology, constitute a continuous 100-Myr-long chemical fossil record of demosponges through the terminal Neoproterozoic and into the Early Cambrian epoch. The demosponge steranes occur in strata that underlie the Marinoan cap carbonate (>635 Myr ago). They currently represent the oldest evidence for animals in the fossil record, and are evidence for animals pre-dating the termination of the Marinoan glaciation. This suggests that shallow shelf waters in some late Cryogenian ocean basins (>635 Myr ago) contained dissolved oxygen in concentrations sufficient to support basal metazoan life at least 100 Myr before the rapid diversification of bilaterians during the Cambrian explosion. Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, 713 Myr ago in Oman).

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URLURL TypeDescription ReadCube access
Love, Gordon D.0000-0002-6516-014X
Fike, David A.0000-0003-2848-0328
Grotzinger, John P.0000-0001-9324-1257
Summons, Roger E.0000-0002-7144-8537
Additional Information:© 2009 Nature Publishing Group. Received 23 September 2008; Accepted 27 November 2008. Funding support for this work came from Petroleum Development Oman (PDO), the NASA Exobiology Program, the NSF EAR Program, the Agouron Institute and the NASA Astrobiology Institute. We thank PDO for access to sample materials and Z. Rawahi and P. Taylor, in particular, for their input. C. Colonero, R. Kayser and A. Lewis provided laboratory assistance, including the maintenance of mass spectrometers at MIT. G.D.L. interpreted the data and wrote the manuscript with input from R.E.S, D.A.F, A.S.B and E.G. G.D.L., E.G., C.S. and A.E.K. acquired the Huqf biomarker data working in the research group of R.E.S. A.S.B. and M.B. screened extant demosponges for their sterol contents. C.E.S. and W.M. made facilities available for HyPy experiments on kerogens and trained C.S. to use the equipment. J.P.G. provided a robust stratigraphic framework for the Huqf Supergroup in the SOSB and with D.A.F. identified key sedimentary rock samples to use in this investigation. S.A.B and D.J.C. measured important U–Pb ages for ash beds and detritral zircons through the stratigraphy to constrain the age range and distribution of our demosponge biomarkers.
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Petroleum Development OmanUNSPECIFIED
Agouron InstituteUNSPECIFIED
Issue or Number:7230
Record Number:CaltechAUTHORS:20090807-101203081
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14867
Deposited By: Tony Diaz
Deposited On:07 Aug 2009 20:25
Last Modified:13 Dec 2019 02:23

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