The soft-bodied Ediacara biota (571–541 million years ago) represents the oldest complex large organisms in the fossil record, providing a bridge between largely microbial ecosystems of the Precambrian and the animal-dominated world of the Phanerozoic, potentially holding clues about the early evolution of Metazoa. However, the nature of most Ediacaran organisms remains unresolved, partly due to their enigmatic non-actualistic preservation. Here, we show that Flinders-style fossilization of Ediacaran organisms was promoted by unusually prolonged conservation of organic matter, coupled with differences in rheological behaviour of the over- and underlying sediments. In contrast with accepted models, cementation of overlying sand was not critical for fossil preservation, which is supported by the absence of cement in unweathered White Sea specimens and observations of soft sediment deformation in South Australian specimens. The rheological model, confirmed by laboratory simulations, implies that Ediacaran fossils do not necessarily reflect the external shape of the organism, but rather the morphology of a soft external or internal organic ‘skeleton’. The rheological mechanism provides new constraints on biological interpretations of the Ediacara biota.
Subscribe to Journal
Get full journal access for 1 year
only $8.67 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
All materials are available within the main text and Supplementary Information files. Palaeontological specimens from South Australia are stored at the South Australian Museum. Specimens from the White Sea area are stored at the Borissiak Palaeontological Institute. Thin sections and higher-quality images are available from the corresponding authors on request.
Fedonkin, M. A. & Waggoner, B. M. The late Precambrian fossil Kimberella is a mollusc-like bilaterian organism. Nature 388, 868–871 (1997).
Ivantsov, A. Y. Paleontological evidence for the supposed Precambrian occurrence of mollusks. Paleontol. J. 44, 1552–1559 (2010).
Antcliffe, J. B., Gooday, A. J. & Brasier, M. D. Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis of Palaeopascichnus. Palaeontology 54, 1157–1175 (2011).
Seilacher, A., Grazhdankin, D. & Legouta, A. Ediacaran biota: the dawn of animal life in the shadow of giant protists. Paleontol. Res. 7, 43–54 (2003).
Kolesnikov, A. V. et al. The oldest skeletal macroscopic organism Palaeopascichnus linearis. Precambrian Res. 316, 24–37 (2018).
Bobrovskiy, I., Hope, J. M., Krasnova, A., Ivantsov, A. & Brocks, J. J. Molecular fossils from organically preserved Ediacara biota reveal cyanobacterial origin for Beltanelliformis. Nat. Ecol. Evol. 2, 437–440 (2018).
Ivantsov, A. Y., Gritsenko, V. P., Konstantinenko, L. I. & Zakrevskaya, M. A. Revision of the problematic Vendian macrofossil Beltanelliformis (=Beltanelloides, Nemiana). Paleontol. J. 48, 1415–1440 (2014).
Xiao, S. & Laflamme, M. On the eve of animal radiation: phylogeny, ecology and evolution of the Ediacara biota. Trends Ecol. Evol. 24, 31–40 (2009).
Budd, G. E. & Jensen, S. The origin of the animals and a ‘Savannah’ hypothesis for early bilaterian evolution. Biol. Rev. 92, 446–473 (2017).
Brasier, M. D. & Antcliffe, J. B. Dickinsonia from Ediacara: a new look at morphology and body construction. Palaeogeogr. Palaeoclimatol. Palaeoecol. 270, 311–323 (2008).
Droser, M. L., Gehling, J. G. & Jensen, S. R. Assemblage palaeoecology of the Ediacara biota: the unabridged edition? Palaeogeogr. Palaeoclimatol. Palaeoecol. 232, 131–147 (2006).
Dzik, J. Organic membranous skeleton of the Precambrian metazoans from Namibia. Geology 27, 519–522 (1999).
Parry, L. A. et al. Soft-bodied fossils are not simply rotten carcasses—toward a holistic understanding of exceptional fossil preservation. Bioessays 40, 1700167 (2018).
Narbonne, G. M. The Ediacara biota: Neoproterozoic origin of animals and their ecosystems. Annu. Rev. Earth Planet. Sci. 33, 421–442 (2005).
Waggoner, B. The Ediacaran biotas in space and time. Integr. Comp. Biol. 43, 104–113 (2003).
Grazhdankin, D. Patterns of distribution in the Ediacaran biotas: facies versus biogeography and evolution. Paleobiology 30, 203–221 (2004).
Boag, T. H., Darroch, S. A. F. & Laflamme, M. Ediacaran distributions in space and time: testing assemblage concepts of earliest macroscopic body fossils. Paleobiology 42, 574–594 (2016).
Wade, M. Preservation of soft-bodied animals in Precambrian sandstones at Ediacara, South Australia. Lethaia 1, 238–267 (1968).
Gehling, J. G. Microbial mats in terminal Proterozoic siliciclastics; Ediacaran death masks. Palaios 14, 40–57 (1999).
Liu, A. G. Framboidal pyrite shroud confirms the ‘death mask’ model for moldic preservation of Ediacaran soft-bodied organisms. Palaios 31, 259–274 (2016).
Gibson, B. M., Schiffbauer, J. D. & Darroch, S. A. F. Ediacaran-style decay experiments using mollusks and sea anemones. Palaios 33, 185–203 (2018).
Liu, A. G., McMahon, S., Matthews, J. J., Still, J. W. & Brasier, A. T. Petrological evidence supports the death mask model for the preservation of Ediacaran soft-bodied organisms in South Australia. Geology 47, 215–218 (2019).
Serezhnikova, E. A. in Advances in Stromatolite Geobiology 525–535 (Springer, Berlin & Heidelberg, 2011).
Tarhan, L. G., Hood, A. v. S., Droser, M. L., Gehling, J. G. & Briggs, D. E. G. Exceptional preservation of soft-bodied Ediacara biota promoted by silica-rich oceans. Geology 44, 951–954 (2016).
Callow, R. H. T. & Brasier, M. D. Remarkable preservation of microbial mats in Neoproterozoic siliciclastic settings: implications for Ediacaran taphonomic models. Earth Sci. Rev. 96, 207–219 (2009).
Gehling, J. G. & Droser, M. L. Textured organic surfaces associated with the Ediacara biota in South Australia. Earth Sci. Rev. 96, 196–206 (2009).
Seilacher, A. Biomat-related lifestyles in the Precambrian. Palaios 14, 86–93 (1999).
Dzik, J. Anatomical information content in the Ediacaran fossils and their possible zoological affinities. Integr. Comp. Biol. 43, 114–126 (2003).
Fedonkin, M. A. in Origin and Early Evolution of the Metazoa (eds Lipps, J. H. & Signor, P. W.) 87–129 (Springer, 1992).
Cai, Y., Schiffbauer, J. D., Hua, H. & Xiao, S. Preservational modes in the Ediacaran Gaojiashan Lagerstätte: pyritization, aluminosilicification, and carbonaceous compression. Palaeogeogr. Palaeoclimatol. Palaeoecol. 326-328, 109–117 (2012).
Orr, P. J., Briggs, D. E. G. & Kearns, S. L. Cambrian Burgess Shale animals replicated in clay minerals. Science 281, 1173–1175 (1998).
Gehling, J., Droser, M., Jensen, S., Runnegar, B. & Briggs, D. Evolving form and function: fossils and development. In Proc. Symposium Honouring Adolf Seilacher for His Contributions to Paleontology, in Celebration of His 80th Birthday (ed. Briggs, D. E. G.) 43–66 (Yale Univ. Press, 2005).
Ivantsov, A. Y. Feeding traces of proarticulata—the Vendian metazoa. Paleontol. J. 45, 237–248 (2011).
Seilacher, A. Vendozoa: organismic construction in the Proterozoic biosphere. Lethaia 22, 229–239 (1989).
Evans, S. D., Droser, M. L. & Gehling, J. G. Dickinsonia liftoff: evidence of current derived morphologies. Palaeogeogr. Palaeoclimatol. Palaeoecol. 434, 28–33 (2015).
Retallack, G. J. Were the Ediacaran fossils lichens? Paleobiology 20, 523–544 (1994).
Jeong, S. W., Locat, J., Leroueil, S. & Malet, J.-P. Rheological properties of fine-grained sediment: the roles of texture and mineralogy. Can. Geotech. J. 47, 1085–1100 (2010).
Darroch, S. A. F., Laflamme, M., Schiffbauer, J. D. & Briggs, D. E. G. Experimental formation of a microbial death mask. Palaios 27, 293–303 (2012).
Verruijt, A. An Introduction to Soil Mechanics Vol. 30 (Springer, 2018).
Panagiotopoulos, I., Voulgaris, G. & Collins, M. B. The influence of clay on the threshold of movement of fine sandy beds. Coast. Eng. 32, 19–43 (1997).
Tarhan, L. G., Droser, M. L., Gehling, J. G. & Dzaugis, M. P. Taphonomy and morphology of the Ediacara form genus Aspidella. Precambrian Res. 257, 124–136 (2015).
Burzynski, G., Narbonne, G. M., Alexander Dececchi, T. & Dalrymple, R. W. The ins and outs of Ediacaran discs. Precambrian Res. 300, 246–260 (2017).
Ivantsov, A. Y. Reconstruction of Charniodiscus yorgensis (Macrobiota from the Vendian of the White Sea). Paleontol. J. 50, 1–12 (2016).
Noffke, N. The criteria for the biogeneicity of microbially induced sedimentary structures (MISS) in Archean and younger, sandy deposits. Earth Sci. Rev. 96, 173–180 (2009).
Bobrovskiy, I. et al. Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals. Science 361, 1246–1249 (2018).
Steiner, M. & Reitner, J. Evidence of organic structures in Ediacara-type fossils and associated microbial mats. Geology 29, 1119–1122 (2001).
Kenchington, C. G. & Wilby, P. R. in Reading and Writing of the Fossil Record: Preservational Pathways to Exceptional Fossilization (eds Laflamme, M., Darroch, S. A. F. & Schiffbauer, J. D.) 101–122 (Cambridge Univ. Press, 2017).
Liu, A. G., McIlroy, D., Antcliffe, J. B. & Brasier, M. D. Effaced preservation in the Ediacara biota and its implications for the early macrofossil record. Palaeontology 54, 607–630 (2011).
Fedonkin, M. A., Simonetta, A. & Ivantsov, A. Y. New data on Kimberella, the Vendian mollusc-like organism (White Sea region, Russia): palaeoecological and evolutionary implications. Geol. Soc. Lond. Spec. Publ. 286, 157–179 (2007).
Dzik, J. & Ivantsov, A. Y. Internal anatomy of a new Precambrian dickinsoniid dipleurozoan from northern Russia. Neues Jahrb. Geol. Palaontol. Monatsh. 385–396 (2002).
The study was funded by Australian Research Council grants DP160100607 and DP170100556 (to J.J.B.) and Russian Foundation for Basic Research project number 17-05-02212A (to I.B., A.K. and A.I). I.B. acknowledges an Australian Government Research Training Program stipend scholarship. The authors are grateful to A. Nagovitsyn, P. Rychkov, V. Rychkov, S. Rychkov, T. Rychkova and A. Makushkina for help in the field, L. Zaytseva for help with scanning electron microscopy imaging, J. M. Hope, J. Wurtzel, S. Eggins, A. Rummery and R. Kerr for providing materials for the taphonomic experiments, M.-A. Binnie and J. G. Gehling for providing access to the South Australian Museum collections, and N. J. Butterfield and A. G. Liu for helpful comments on this study.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Bobrovskiy, I., Krasnova, A., Ivantsov, A. et al. Simple sediment rheology explains the Ediacara biota preservation. Nat Ecol Evol 3, 582–589 (2019). https://doi.org/10.1038/s41559-019-0820-7
Palaeogeography, Palaeoclimatology, Palaeoecology (2020)
Paleontological Journal (2019)