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Published November 10, 2009 | Published + Supplemental Material
Journal Article Open

Complex embryos displaying bilaterian characters from Precambrian Doushantuo phosphate deposits, Weng'an, Guizhou, China

Abstract

Three-dimensionally preserved embryos from the Precambrian Ediacaran Doushantuo Formation, Weng'an, Guizhou, southern China, have attracted great attention as the oldest fossil evidence yet found for multicellular animal life on Earth. Many embryos are early cleavage embryos and most of them yield a limited phylogenetic signal. Here we report the discovery of two Doushantuo embryos that are three-dimensionally preserved and complex. Imaging techniques using propagation phase-contrast based synchrotron radiation microtomography (PPC-SR-μCT) reveal that the organization of cells demonstrates several bilaterian features, including the formation of anterior-posterior, dorso-ventral, and right-left polarities, and cell differentiation. Unexpectedly, our observations show a noticeable difference in organization patterns between the embryos, suggesting that they represent two distinct taxa. These embryos provide further evidence for the presence of bilaterian animals in the Doushantuo biota. Furthermore, these bilaterians had already diverged into distantly related groups at least 40 million years before the Cambrian radiation, indicating that the last common ancestor of the bilaterians lived much earlier than is usually thought.

Additional Information

© 2009 by the National Academy of Sciences. Edited by J. William Schopf, University of California, Los Angeles, CA, and approved September 18, 2009 (received for review May 5, 2009). Published online before print October 26, 2009. Author contributions: J.-Y.C., D.J.B., and M.G.H. designed research; J.-Y.C., G.L., F.G., A.R.C., C.-Y.Z., D.-C.X., X.L., and Z.-J.Y. performed research; G.L., F.G., and P.T. analyzed data; and J.-Y.C., D.J.B., and M.G.H. wrote the paper. We thank Eric Davidson for aid and support throughout the analysis of these specimens and completion of this paper, Jon Mallatt and Stephen Q. Dornbos for helpful comments on the manuscript, and X.-Z. Li and Z.-Z. Mu for technical assistance. This work was supported by Chinese Academy of Science Grants KZCX3-SW-14 and 542006IHEPZZBS50639; National Basic Research Program of China Grants 2007CB815800 and 2006CB806400; National Science Foundation of China Grants 40432006, 40772001, and 10675140); European Synchrotron Radiation Facility (ID19 beamline) for beamtime access (proposal ec-138); 111 and 985–2 Projects of Nanjing University; Caltech through the Gordon and Betty Moore Distinguished Scholar Program (to J.-Y.C.); National Aeronautics and Space Administration Ames Research Center Grant NAG2–1541 and the University of Southern California (to D.J.B.); the Beckman Institute (to R.A.C.), and the Caltech Camilla Chandler Frost Fellowship (to F.G.).

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Published - Chen2009p6442P_Natl_Acad_Sci_Usa.pdf

Supplemental Material - Chen2009p6442P_Natl_Acad_Sci_Usa_supp.pdf

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Created:
August 21, 2023
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October 19, 2023