Problematic macrofossils from Ediacaran successions in the North China and Chaidam blocks: implications for their evolutionary roots and biostratigraphic significance | Journal of Paleontology | Cambridge Core (original) (raw)

Abstract

Upper Neoproterozoic successions in the North China and nearby Chaidam blocks are poorly documented. North China successions typically consist of a diamictite unit overlain by siltstone, sandstone, or slate. Similar successions occur in Chaidam, although a cap carbonate lies atop the diamictite unit. The diamictites in both blocks have been variously interpreted as Cryogenian, Ediacaran, or Cambrian glacial deposits. In this paper, we describe problematic macrofossils collected from slate of the upper Zhengmuguan Formation in North China and sandstone of the Zhoujieshan Formation in Chaidam; both fossiliferous formations conformably overlie the aforementioned diamictites. Some of these fossils were previously interpreted as animal traces. Our study recognizes four genera and five species—Helanoichnus helanensis Yang in Yang and Zheng, 1985, Palaeopascichnus minimus n. sp., Palaeopascichnus meniscatus n. sp., Horodyskia moniliformis? Yochelson and Fedonkin, 2000, and Shaanxilithes cf. ningqiangensis Xing et al., 1984. None of these taxa can be interpreted as animal traces. Instead, they are problematic body fossils of unresolved phylogenetic affinities. The fundamental bodyplan similarity between Horodyskia and Palaeopascichnus, both with serially repeated elements, indicates a possible phylogenetic relationship. Thus, at least some Ediacaran organisms may have a deep root because Horodyskia also occurs in Mesoproterozoic successions.

Among the four genera reported here, Palaeopascichnus Palij, 1976 and Shaanxilithes Xing et al., 1984 have been known elsewhere in upper Ediacaran successions, including the Dengying Formation (551-542 Ma) in South China. If these two genera have biostratigraphic significance, the fossiliferous units in North China and Chaidam may be upper Ediacaran as well. Thus, the underlying diamictites in North China and Chaidam cannot be of Cambrian age, although their correlation with Ediacaran and Cryogenian glaciations remains unclear. As no other Neoproterozoic diamictite intervals are known in North China and Chaidam, perhaps only one Neoproterozoic glaciation is recorded in that area.

References

Agardh, C. A. 1823. Species Algarum, 1(2). , p. 169–531.Google Scholar

Amthor, J. E., Grotzinger, J. P., Schröder, S., Bowring, S. A., Ramezani, J., Martin, M. W., and Matter, A. 2003. Extinction of Cloudina and Namacalathus at the Precambrian–Cambrian boundary in Oman. Geology, 31:431–434.2.0.CO;2>CrossRefGoogle Scholar

Azpeitia Moros, F. 1933. Datos para el estudio paleontológica del Flysch de la Costa Cantábrica y de algunos otros puntos de España. Boletin del Instituto Geológico y Minero de España, 53:1–65.Google Scholar

Bertrand-Sarfati, J., Moussine-Pouchkine, A., Amard, B., and Ait Kaci Ahmed, A. 1995. First Ediacaran fauna found in western Africa and evidence for an Early Cambrian glaciation. Geology, 23:133–136.2.3.CO;2>CrossRefGoogle Scholar

Bornet, E. and Flahault, C. 1888. Revision des Nostocacées hétérocystées. Annales des Sciences Naturelles Botanique et Biologie Vegetale, VII(7):177–262.Google Scholar

Bowring, S., Myrow, P., Landing, E., Ramezani, J., and Grotzinger, J. 2003. Geochronological constraints on terminal Neoproterozoic events and the rise of metazoans. Geophysical Research Abstracts, 5:13219.Google Scholar

Butterfield, N. J. 1990. Organic preservation of non-mineralizing organisms and the taphonomy of the Burgess Shale. Paleobiology, 16:272–286.CrossRefGoogle Scholar

Chen, M. and Xiao, Z. 1992. Macrofossil biota from upper Doushantuo Formation in eastern Yangtze Gorges, China. Acta Palaeontologica Sinica, 31:513–529.Google Scholar

Chen, M., Chen, X., and Lao, Q. 1975. An introduction to the metazoa fossil from the upper Sinian system in southern Shensi and its stratigraphic significance. Scientia Geologica Sinica, 1975(2):181–190.Google Scholar

Chen, M., Chen, Y., and Qian, Y. 1981. Some tubular fossils from Sinian–Lower Cambrian boundary sequences, Yangtze Gorge. Bulletin, Tianjin Institute of Geology and Mineral Resources, 3:117–124.Google Scholar

Chen, Z. 1999. Late Sinian metazoan tubular fossils from western Hubei and southern Shaanxi, China. , Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, 128 p.Google Scholar

Condon, D., Zhu, M., Bowring, S., Wang, W., Yang, A., and Jin, Y. 2005. U–Pb Ages from the Neoproterozoic Doushantuo Formation, China. Science, 308:95–98.CrossRefGoogle ScholarPubMed

Dewel, R. A. 2000. Colonial origin for Eumetazoa: Major morphological transitions and the origin of bilaterian complexity. Journal of Morphology, 243:35–74.3.0.CO;2-#>CrossRefGoogle ScholarPubMed

Ding, L., Li, Y., and Chen, H. 1992. Discovery of Micrhystridium regulare from Sinian–Cambrian boundary strata in Yichang, Hubei, and its stratigraphic significance. Acta Micropalaeontologica Sinica, 9:303–309.Google Scholar

Dong, L., Xiao, S., Shen, B., Yuan, X., Yan, X., and Peng, Y.. Restudy of the worm-like carbonaceous compression fossils Protoarenicola, Pararenicola, and Sinosabellidites from early Neoproterozoic successions in North China. Palaeogeography Palaeoclimatology Palaeoecology.Google Scholar

Droser, M. L., Gehling, J. G., and Jensen, S. 2005. Ediacaran trace fossils: true and false, p. 125–138. In Briggs, D. E. G. (ed.), Evolving Form and Function: Fossils and Development. Yale Peabody Museum Publications, New Haven, CT.Google Scholar

Droser, M. L., Jensen, S., and Gehling, J. G. 2002. Trace fossils and substrates of the terminal Proterozoic–Cambrian transition: Implications for the record of early bilaterians and sediment mixing. Proceedings National Academy of Sciences, USA, 99:12572–12576.CrossRefGoogle ScholarPubMed

Dzik, J. 2005. Behavioral and anatomical unity of the earliest burrowing animals and the cause of the “Cambrian explosion.” Paleobiology, 31:503–521.CrossRefGoogle Scholar

Fedonkin, M. A. 1980. Iskopaemye sledy dokembrijskikh metazoa. Izvestija Akademij Nauk, Serija Geologicheskaja, 1980:39–46.Google Scholar

Fedonkin, M. A. 1981. Belomorskaya biota venda. Trudy Akademii Nauk SSSR, 342:1–100.Google Scholar

Fedonkin, M. A. 1985. Paleoichnology of Vendian Metazoa, p. 112–116. In Sokolov, B. S. and Ivanovskiy, A. B. (eds.), The Vendian System 1: Historic-Geological and Palaeontological Basis. Nauka, Moscow.Google Scholar

Fedonkin, M. A. 1994. Vendian body fossils and trace fossils, p. 370–388. In Bengtson, S. (ed.), Early Life on Earth. Columbia University Press, New York.Google Scholar

Fedonkin, M. A. and Yochelson, E. L. 2002. Middle Proterozoic (1.5 Ga) Horodyskia moniliformis Yochelson and Fedonkin, the oldest known tissue-grade colonial eucaryote. Smithsonian Contributions to Paleobiology, 94:1–29.CrossRefGoogle Scholar

Gao, Z., Peng, C., Li, Y., Qian, J., and Zhu, S. 1980. The Sinian System and its glacial deposits in Quruqtagh, Xinjiang, p. 186–213. In , Research in Precambrian Geology, Sinian Suberathem in China. Tianjin Science and Technology Press, Tianjin.Google Scholar

Gehling, J. G. 2002. Field Trip Guide Book PRE-3: Terminal Proterozoic–Cambrian of the Flinders Ranges, South Australia. .Google Scholar

Gehling, J. G., Narbonne, G. M., and Anderson, M. M. 2000. The first named Ediacaran body fossil, Aspidella terranovica. Palaeontology, 43:427–456.CrossRefGoogle Scholar

Glaessner, M. F. 1969. Trace fossils from the Precambrian and basal Cambrian. Lethaia, 2:369–393.CrossRefGoogle Scholar

Gooday, A. J. and Nott, J. A. 1982. Intracellular barite crystals in two xenophyophores, Aschemonella ramuliformis and Galatheammina sp. (Protozoa: Rhizopoda) with comments on the taxonomy of A. ramuliformis. Journal of the Marine Biological Association of the United Kingdom, 62:595–605.CrossRefGoogle Scholar

Grazhdankin, D. 2004. Patterns of distribution in the Ediacaran biotas: Facies versus biogeography and evolution. Paleobiology, 30:203–221.2.0.CO;2>CrossRefGoogle Scholar

Grey, K. and Williams, I. R. 1990. Problematic bedding-plane markings from the Middle Proterozoic Manganese Subgroup, Bangemall Basin, Western Australia. Precambrian Research, 46:307–328.CrossRefGoogle Scholar

Guan, B., Wu, R., Hambrey, M. J., and Geng, W. 1986. Glacial sediments and erosional pavements near the Cambrian–Precambrian boundary in western Henan Province, China. Journal of the Geological Society, London, 143:311–323.Google Scholar

Haeckel, E. 1899. Report on the deep-sea Keratosa collected by H.M.S. Challenger during the years 1873-76. Reports of The Scientific Results of The Voyage of The Challenger, Zoology, 32:1–92.Google Scholar

Haines, P. W. 2000. Problematic fossils in the late Neoproterozoic Wonoka Formation, South Australia. Precambrian Research, 100:97–108.CrossRefGoogle Scholar

Han, Y. and Pickerill, R. K. 1995. Taxonomic review of the ichnogenus Helminthopsis Heer 1977 with a statistical analysis of selected ichnospecies. Ichnos, 4:83–118.CrossRefGoogle Scholar

Häntzschel, W. 1975. Treatise on Invertebrate Paleontology, Pt. W, Miscellanea supplement 1 Trace fossils and Problematica. Geological Society of America and University of Kansas, Boulder, Colorado, 269 p.Google Scholar

Heer, O. 1877. Flora Fossilis Helvetiae. Die Vorweltliche Flora der Schweiz. J. Würster, Zürich, 182 p.Google Scholar

Hopwood, J. D., Mann, S., and Gooday, A. J. 1997. The crystallography and possible origin of barium sulphate in deep sea rhizopod protists (Xenophyophorea). Journal of the Marine Biological Association of the United Kingdom, 77:969–987.CrossRefGoogle Scholar

Horodyski, R. J. 1982. Problematic bedding-plane markings from the middle Proterozoic Appekunny argillite, Belt Supergroup, northwestern Montana. Journal of Paleontology, 56:882–889.Google Scholar

Hua, H., Chen, Z., and Zhang, L. 2004. Shaanxilithes from lower Taozichong Formation, Guizhou Province and its geological and paleobiological significance. Journal of Stratigraphy, 28:265–269.Google Scholar

Hua, H., Pratt, B. R., and Zhang, L. 2003. Borings in Cloudina shells: Complex predator-prey dynamics in the terminal Neoproterozoic. Palaios, 18:454–459.2.0.CO;2>CrossRefGoogle Scholar

Hua, H., Chen, Z., Yuan, X., Zhang, L., and Xiao, S. 2005. Skeletogenesis and asexual reproduction in the earliest biomineralizing animal Cloudina. Geology, 33:277–280.CrossRefGoogle Scholar

Ivantsov, A. Y. 1990. New data on the ultrastructure of sabelliditids (Pogonophora?). Paleontologicheskii Zhurnal, 24:125–128.Google Scholar

Jenkins, R. J. F. 1995. The problems and potential of using animal fossils and trace fossils in terminal Proterozoic biostratigraphy. Precambrian Research, 73:51–69.CrossRefGoogle Scholar

Jensen, S. 2003. The Proterozoic and Earliest Cambrian trace fossil record: patterns, problems and perspectives. Integrative and Comparative Biology, 43:219–228.CrossRefGoogle ScholarPubMed

Jensen, S., Droser, M. L., and Gehling, J. G. 2005. Trace fossil preservation and the early evolution of animals. Palaeogeography, Palaeoclimatology, Palaeoecology, 220:19–29.CrossRefGoogle Scholar

Jensen, S., Droser, M. L., and Gehling, J. G. 2006. A critical look at the Ediacaran trace fossil record, p. 115–157. In Xiao, S. and Kaufman, A. J. (eds.), Neoproterozoic Geobiology. Springer, Dordrecht, the Netherlands.CrossRefGoogle Scholar

Ksiażkiewicz, M. 1970. Observations on the ichnofauna of the Polish Carpathians, p. 283–322. In Crimes, T. P. and Harper, J. C. (eds.), Trace Fossils. Seel House Press, Liverpool.Google Scholar

Kumar, S. 1995. Megafossils from the Mesoproterozoic Rohtas Formation (the Vindhyan Supergroup), Katni area, central India. Precambrian Research, 72:171–184.CrossRefGoogle Scholar

Li, R., Yang, S., and Li, W. 1997. Trace Fossils from Sinian–Cambrian Boundary Strata in China. Geological Publishing House, Beijing, 99 p.Google Scholar

Lin, S., Zhang, Y., Zhang, L., Tao, X., and Wang, M. 1986. Body and trace fossils of metazoa and algal macrofossils from the upper Sinian Gaojiashan Formation in southern Shaanxi. Geology of Shaanxi, 4:9–17.Google Scholar

Lu, S. 2002. The Precambrian Geology of Northern Tibet. Geological Publishing House, Beijing, 125 p.Google Scholar

Lu, S., Ma, G., Gao, Z., and Lin, W. 1985. Sinian ice ages and glacial sedimentary facies-areas in China. Precambrian Research, 29:53–63.Google Scholar

Macleay, W. S. 1839. Note on the Annelida, p. 699–701. In Murchison, R. I. (ed.), The Silurian System, Pt. II, Organic Remains. J. Murray, London.Google Scholar

Mangano, M. G., Buatois, L. A., Maples, C. G., and West, R. R. 2000. A new ichnospecies of Nereites from Carboniferous tidal-flat facies of eastern Kansas, USA: Implications for the Nereites-Neonereites debate. Journal of Paleontology, 74:149–157.Google Scholar

Martin, D. M. 2004. Depositional environment and taphonomy of the “strings of beads”: Mesoproterozoic multicellular fossils in the Bangemall Supergroup, Western Australia. Australian Journal of Earth Sciences, 51:555–561.CrossRefGoogle Scholar

Moczydłowska, M. 2003. Earliest Cambrian putative bacterial nanofossils. Memoirs of the Association of Australasian Palaeontologists, 29:1–11.Google Scholar

Mu, Y. 1981. Luoquan tillite of the Sinian System in China, p. 402–413. In Hambrey, M. J. and Harland, W. B. (eds.), Pre-Pleistocene Glacial Record, IGCP 38. Cambridge University Press, Cambridge.Google Scholar

Narbonne, G. M. 1998. The Ediacara Biota: A terminal Neoproterozoic experiment in the evolution of life. GSA Today, 8(2):1–6.Google Scholar

Narbonne, G. M. 2005. The Ediacara Biota: Neoproterozoic origin of animals and their ecosystem. Annual Review of Earth and Planetary Sciences, 33:421–442.CrossRefGoogle Scholar

Narbonne, G. M., Myrow, P. M., Landing, E., and Anderson, M. M. 1987. A candidate stratotype for the Precambrian–Cambrian boundary, Fortune Head, Burin Peninsula, southeastern Newfoundland. Canadian Journal of Earth Sciences, 24:1277–1293.CrossRefGoogle Scholar

Orr, P. J., Briggs, D. E. G., and Kearns, S. L. 1998. Cambrian Burgess Shale animals replicated in clay minerals. Science, 281:1173–1175.CrossRefGoogle ScholarPubMed

Palij, V. M. 1976. Remains of non-skeletal fauna and trace fossils from upper Precambrian and Lower Cambrian deposits of Podolia, p. 63–77. In Ryabenko, V. A. (ed.), Paleontology and Stratigraphy of the upper Precambrian and lower Paleozoic of the south-western part of the East European Platform. Naukova Dumka, Kiev.Google Scholar

Pawlowski, J., Holzmann, M., Fahrnia, J., and Richardson, S. L. 2003. Small subunit ribosomal DNA suggests that the xenophyophorean Syringammina corbicula is a foraminiferan. Journal of Eukaryotic Microbiology, 50:483–487.CrossRefGoogle ScholarPubMed

Qian, M., Yuan, X., Wang, Y., and Yan, Y. 2000. New material of metaphytes from the Neoproterozoic Jinshanzhai Formation in Huaibei, North Anhui, China. Acta Palaeontologica Sinica, 39:516–520.Google Scholar

Schafhäutl, K. E. 1851. Geognostische Untersuchungen des Südbayrischen Alpendebirgers. Literarisch-Artistische Anstalt, München, 208 p.Google Scholar

Seilacher, A., Grazhdankin, D., and Legouta, A. 2003. Ediacaran biota: The dawn of animal life in the shadow of giant protists. Paleontological Research, 7:43–54.CrossRefGoogle Scholar

Seilacher, A., Buatois, L. A., and Mángano, M. G. 2005. Trace fossils in the Ediacaran–Cambrian transition: Behavioral diversification, ecological turnover and environmental shift. Palaeogeography, Palaeoclimatology, Palaeoecology, 227:323–356.CrossRefGoogle Scholar

Sokolov, B. S. 1967. Drevneyshiye pognofory [The oldest Pogonophora]. Doklady Akademii Nauk SSSR, 177:201–204. Google Scholar

Sokolov, B. S. 1968. Vendian and Early Cambrian Sabellitida (Pogonophora) of the SSSR. , p. 79–86.Google Scholar

Sokolov, B. S. 1972. Vendskiy etap v istorii Zemli [The Vendian Period in Earth history], p. 114–124, Mezhdunarodnyj geologicheskij kongress XXIV sessiya. Daldadov sovetskikh geologov. Problema 7. Paleontologiya. Nauka, Moscow.Google Scholar

Sokolov, B. S. and Iwanowski, A. B. 1990. The Vendian System, 1: Paleontology. Springer-Verlag, Heidelberg, 383 p.Google Scholar

Sun, W., Wang, G., and Zhou, B. 1986. Macroscopic worm-like body fossils from the Upper Precambrian (900-700Ma), Huainan district, Anhui, China and their stratigraphic and evolutionary significance. Precambrian Research, 31:377–403.Google Scholar

Tendal, O. S. 1972. A monograph of the Xenophyophoria (Rhizopodea, Protozoa). Galathea Report, 12:7–99.Google Scholar

Tendal, O. S., Swinbanks, D. D., and Shirayama, Y. 1982. A new infaunal xenophyophore (Xenophyophorea, Protozoa) with notes on its ecology and possible trace fossil analogues. Oceanologica Acta, 5:325–329.Google Scholar

Uchman, A. 1995. Taxonomy and palaeoecology of flysch trace fossils: the Marnoso-arenacea Formation and associated facies (Miocene, Northern Apennines, Italy). Beringeria, 15:1–115.Google Scholar

Urbanek, A. and Mierzejewska, G. 1977. The fine structure of zooidal tubes in Sabelliditida and Pogonophora with reference to their affinity. Acta Palaeontologica Polonica, 22:223–240.Google Scholar

Urbanek, A. D. and Rozanov, A. Y. 1983. Upper Precambrian and Cambrian Palaeontology of the East-European Platform. Publishing House Wydawnictwa Geologiczne, Warszawa, 158 p.Google Scholar

Walcott, C. D. 1899. Pre-Cambrian fossiliferous formations. Bulletin of the Geological Society of America, 10:199–244. CrossRefGoogle Scholar

Walter, M. R., Du, R., and Horodyski, R. J. 1990. Coiled carbonaceous megafossils from the middle Proterozoic of Jixian (Tianjin) and Montana. American Journal of Science, 290-A:133–148.Google Scholar

Walter, M. R., Oehler, J. H., and Oehler, D. Z. 1976. Megascopic algae 1300 million years old from the Belt Supergroup, Montana: A reinterpretation of Walcott's Helminthoidichnites. Journal of Paleontology, 50:872–881.Google Scholar

Wang, G. 1982. Late Precambrian Annelida and Pogonophora from the Huainan of Anhui Province. Bulletin of the Tianjin Institute of Geology and Mineral Resources, 6:9–22.Google Scholar

Wang, H. 1985. Atlas of the Palaeogeography of China. Cartographic Publishing House, Beijing, 85 p.Google Scholar

Wang, Y., Lu, S., Gao, Z., Lin, W., and Ma, G. 1981. Sinian tillites of China, p. 386–401. In Hambrey, M. J. and Harland, W. B. (eds.), Pre-Pleistocene Glacial Record, IGCP 38. Cambridge University Press, Cambridge.Google Scholar

Wang, Y., Zhuang, Q., Shi, C., Liu, J., and Zheng, L. 1980. Quanji Group along the northern border of Chaidamu Basin, p. 214–230. In , Research on Precambrian Geology, Sinian Suberathem in China, Tianjin.Google Scholar

Wetzel, A. and Bromley, R. 1996. Re-evaluation of the ichnogenus Helminthopsis - a new look at the type material. Palaeontology, 30:1–19.Google Scholar

Xiao, S., Yuan, X., Steiner, M., and Knoll, A. H. 2002. Macroscopic carbonaceous compressions in a terminal Proterozoic shale: A systematic reassessment of the Miaohe biota, South China. Journal of Paleontology, 76:345–374.2.0.CO;2>CrossRefGoogle Scholar

Xiao, S., Bao, H., Wang, H., Kaufman, A. J., Zhou, C., Li, G., Yuan, X., and Ling, H. 2004. The Neoproterozoic Quruqtagh Group in eastern Chinese Tianshan: Evidence for a post-Marinoan glaciation. Precambrian Research, 130:1–26.CrossRefGoogle Scholar

Xing, Y., Duan, C., Liang, Y., and Cao, R. 1985. Late Precambrian Palaeontology of China. Geological Publishing House, Beijing, 243 p.Google Scholar

Xing, Y., Ding, Q., Luo, H., He, T., and Wang, Y. 1984. The Sinian–Cambrian Boundary of China. Bulletin of the Institute of Geology, Chinese Academy of Geological Sciences 10:1–262.Google Scholar

Yang, S. and Zheng, Z. 1985. The Sinian trace fossils from Zhengmuguan Formation of Helanshan Mountain, Ningxia. Earth Science (Journal of Wuhan College of Geology), 10:9–18.Google Scholar

Yang, S., Zhang, J., and Yang, M. 2004. Trace Fossils of China. Science Press, Beijing, 353 p.Google Scholar

Yanichevsky, M. E. 1926. Ob ostatkakh trubchatykh chervej iz kembrijskoj Sinej Gliny [On remains of tube-dwelling worms from the Cambrian Blue Clay]. Ezhegodnik Vsesoyuznogo Paleontologicheskogo Obshchestva, 4:99–111.Google Scholar

Yochelson, E. L. and Fedonkin, M. A. 2000. A new tissue-grade organism 1.5 billion years old from Montana. Proceedings of the Biological Society of Washington, 113:843–847.Google Scholar

Zhang, L. 1986. A discovery and preliminary study of the late stage of late Gaojiashan biota from Sinian in Ningqiang County, Shaanxi. Bulletin of the Xi'an Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, 13:67–88.Google Scholar

Zhao, X., Zhang, L., Zou, X., Wang, S., and Hu, Y. 1980. Sinian tillites in Northwest China and their stratigraphic significance, p. 164–185. In , Research on Precambrian Geology Sinian Suberathem in China. Tianjin Science and Technology Press, Tianjin.Google Scholar

Zhao, Z., Xing, Y., Ma, G., Yu, W., and Wang, Z. 1980. The Sinian System of eastern Yangtze Gorges, Hubei, p. 31–55. In , Research in Precambrian Geology: Sinian Suberathem in China. Tianjin Science and Technology Press, Tianjin.Google Scholar

Zheng, W. 1980. A new occurence of fossil group Chuaria from the Sinian System in north Anhui and its geological meaning. Bulletin of the Tianjin Institute of Geology and Mineral Resources, 1:49–69.Google Scholar

Zheng, Z., Li, Y., Lu, S., and Li, H. 1994. Lithology, sedimentology and genesis of the Zhengmuguan Formation of Ningxia, China, p. 101–108. In Deynoux, M., Miller, J. M. G., Domack, E. W., Eyles, N., Fairchild, I. J., and Young, G. M. (eds.), Earth's Glacial Record. Cambridge University Press, Cambridge.Google Scholar

Zhuravlev, A. Y. 1993. Were Ediacaran Vendobionta multicellulars? Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 190:299–314.Google Scholar