Hostname: page-component-78c5997874-dh8gc Total loading time: 0 Render date: 2024-11-14T22:11:49.100Z Has data issue: false hasContentIssue false

Diversity of cnidarians and cycloneuralians in the Fortunian (early Cambrian) Kuanchuanpu Formation at Zhangjiagou, South China

Published online by Cambridge University Press:  15 February 2018

Tiequan Shao
Affiliation:
School of Earth Science and Resources, Chang’an University, Xi’an 710054, China 〈zytqshao@chd.edu.cn〉, 〈757230401@qq.com〉, 〈stotto@163.com〉
Hanhua Tang
Affiliation:
School of Earth Science and Resources, Chang’an University, Xi’an 710054, China 〈zytqshao@chd.edu.cn〉, 〈757230401@qq.com〉, 〈stotto@163.com〉
Yunhuan Liu*
Affiliation:
School of Earth Science and Resources, Chang’an University, Xi’an 710054, China 〈zytqshao@chd.edu.cn〉, 〈757230401@qq.com〉, 〈stotto@163.com〉
Dieter Waloszek
Affiliation:
University of Lund, Sölvegatan 12, SE-22362 Lund, Sweden 〈dieter.waloszek@geol.lu.se〉
Andreas Maas
Affiliation:
Galgenackerweg 25, 89134 Blaustein, Germany 〈maas.blaustein@freenet.de〉
Huaqiao Zhang*
Affiliation:
State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China 〈hqzhang@nigpas.ac.cn〉
*
*Corresponding authors
*Corresponding authors

Abstract

The latest discovery of microfossils from the lower Cambrian (Fortunian Stage) Zhangjiagou Lagerstätte in South China are presented. This lagerstätte is rich in exceptionally preserved microfossils, including embryos of Olivooides multisulcatus, Olivooides mirabilis, and Pseudooides prima; hatched stages of O. multisulcatus, O. mirabilis, Hexaconularia sichuanensis, and Quadrapyrgites quadratacris; and cycloneuralians represented by Eopriapulites sphinx. The largest known fragment of O. mirabilis implies that its adult length can be more than 9.0 mm with at least 50 annuli, and the longest known specimen of Q. quadratacris has at least 18 annuli. These unusually large specimens refute the non-feeding larvae hypothesis for Olivooides and Quadrapyrgites.

Based on the current material, it is inferred that (1) early cnidarians have a high diversity in the Fortunian Stage; (2) P. prima might represent the embryonic stages of H. sichuanensis; (3) adults of Olivooides and Quadrapyrgites may have reached centimeter-scale dimensions with more than 50 annuli; (4) Olivooides and Quadrapyrgites may be better interpreted as coronate scyphozoans; (5) cycloneuralians also had a high diversity in the Zhangjiagou Lagerstätte; and (6) cycloneuralians might have originally been part of the early Cambrian meiofauna rather than belonging to the macrobenthos. Such ancestral cycloneuralians might have been Eopriapulites-like, possessing pentaradially symmetric, backward pointing, and internally hollow introvert scalids used as locomotory devices.

Type
Articles
Copyright
Copyright © 2018, The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ax, P., 2003, Multicellular Animals: Order in Nature-System Made by Man, v. III: Berlin Heidelberg, New York, Springer-Verlag, 317 p.Google Scholar
Bailey, J.V., Joye, S.B., Kalanetra, K.M., Flood, B.E., and Corsetti, F.A., 2007, Evidence of giant sulphur bacteria in Neoproterozoic phosphorites: Nature, v. 445, p. 198201.CrossRefGoogle ScholarPubMed
Bengtson, S., and Yue, Z., 1997, Fossilized metazoan embryos from the earliest Cambrian: Science, v. 277, p. 16451648.Google Scholar
Bengtson, S., Conway Morris, S., Cooper, B.J., Jell, P.A., and Runnegar, B.N., 1990, Early Cambrian Fossils from South Australia. Memoir 9 of the Association of Australian Palaeontologists: Brisbane, Association of Australian Palaeontologists, 364 p.Google Scholar
Bengtson, S., Cunningham, J.A., Yin, C., and Donoghue, P.C.J., 2012, A merciful death for the “earliest bilaterian,”: Vernanimalcula: Evolution & Development, v. 14, p. 421427.Google Scholar
Budd, G.E., 2001, Tardigrades as “stem-group arthropods”: the evidence from the Cambrian fauna: Zoologischer Anzeiger, v. 240, p. 265279.Google Scholar
Budd, G.E., 2003a, The Cambrian fossil record and the origin of the phyla: Integrative and Comparative Biology, v. 43, p. 157165.Google Scholar
Budd, G.E., 2003b, Arthropods as ecdysozoans: the fossil evidence, in Legakis, A., Sfenthourakis, S., Polymeni, R., and Thessalou-Legaki, M., eds., The New Panorama of Animal Evolution: Proceedings of the 18th International Congress on Zoology, p. 479487.Google Scholar
Budd, G.E., 2013, At the origin of animals: the revolutionary Cambrian fossil record: Current Genomics, v. 14, p. 344354.Google Scholar
Budd, G.E, and Jackson, I.S.C., 2015, Ecological innovations in the Cambrian and the origins of the crown group phyla: Philosophical Transactions B, v. 371, p. 20150287.Google Scholar
Chen, J.-Y., 2004, The Dawn of Animal World: Nanjing, Jiangsu Science and Technology Press, 366 p.Google Scholar
Chen, J.-Y., Bottjer, D.J., Oliveri, P., Dornbos, S.Q., Gao, F., Ruffins, S., Chi, H., Li, C.-W., and Davidson, E.H., 2004, Small bilaterian fossils from 40 to 55 million years before the Cambrian: Science, v. 305, p. 218222.Google Scholar
Chen, J.-Y., Waloszek, D., Maas, A., Braun, A., Huang, D.-Y., Wang, X.-Q., and Stein, M., 2007, Early Cambrian Yangtze Plate Maotianshan Shale macrofauna biodiversity and the evolution of predation: Palaeogeography Palaeoclimatology Palaeoecology, v. 254, p. 250272.Google Scholar
Chen, L., Xiao, S., Pang, K., Zhou, C., and Yuan, X., 2014, Cell differentiation and germ-soma separation in Ediacaran animal embryo-like fossils: Nature, v. 516, p. 238241.Google Scholar
Conway Morris, S., and Chen, M., 1992, Carinachitiids, hexangulaconulariids, and Punctatus: problematic metazoans from the early Cambrian of South China: Journal of Paleontology, v. 66, p. 384406.Google Scholar
Conway Morris, S., and Peel, J.S., 2010, New palaeoscolecidan worms from the Lower Cambrian: Sirius Passet, Latham Shale and Kinzers Shale: Acta Palaeontologica Polonica, v. 55, p. 141156.Google Scholar
Decraemer, W., 1986, Marine nematodes from Guadeloupe and other Caribbean Islands. VI. Taxonomy of the Desmoscolex frontalis complex (Desmoscolecini): Bulletin du Muséum national d’ Histoire naturelle de Paris, Series 4, v. 8A, 2, p. 295311.Google Scholar
Dong, X.-P., Donoghue, P.C.J., Cheng, H., and Liu, J.-B., 2004, Fossil embryos from the Middle and Late Cambrian period of Hunan, south China: Nature, v. 427, p. 237240.CrossRefGoogle ScholarPubMed
Dong, X.-P., Bengtson, S., Gostling, N.J., Cunningham, J.A., Harvey, T.H.P., Kouchinsky, A., Val’kov, A.K., Repetski, J.E., Stampanoni, M., Marone, E., and Donoghue, P.C.J., 2010, The anatomy, taphonomy, taxonomy and systematic affinity of Markuelia: early Cambrian to Early Ordovician scalidophorans: Palaeontology, v. 53, p. 12911314.Google Scholar
Dong, X.-P., Cunningham, J.A., Bengtson, S., Thomas, C.-W., Liu, J., Stampanoni, M., and Donoghue, P.C.J., 2013, Embryos, polyps and medusae of the early Cambrian scyphozoan Olivooides : Proceedings of the Royal Society B (Biological Sciences), v. 280, p. 20130071.CrossRefGoogle ScholarPubMed
Dong, X.-P., Vargas, K., Cunningham, J.A., Zhang, H.Q., Liu, T., Chen, F., Liu, J.-B., Bengtson, S., and Donoghue, P.C.J., 2016, Developmental biology of the early Cambrian cnidarian Olivooides : Palaeontology, v. 59, p. 387407.CrossRefGoogle Scholar
Donoghue, P.C.J., Kouchinsky, A., Bengtson, S., Cunningham, J., Dong, X.-P., Repetski, J.E., Val’kov, A.K., and Waloszek, D., 2006a, Fossilized embryos are widespread but the record is temporally and taxonomically biased: Evolution & Development, v. 8, p. 232238.Google Scholar
Donoghue, P.C.J., Bengtson, S., Dong, X.-P., Gostling, N.J., Huldtgren, T., Cunningham, J.A., Yin, C., Yue, Z., Peng, F., and Stampanoni, M., 2006b, Synchrotron X-ray tomographic microscopy of fossil embryos: Nature, v. 442, p. 680683.Google Scholar
Donoghue, P.C.J., Cunningham, J.A., Dong, X.-P., and Bengtson, S., 2015, Embryology in deep time, in Wanninger, A., ed., Evolutionary Developmental Biology of Invertebrates 1: Introduction, Non-Bilateria, Acoelomorpha, Xenoturbellida, Chaetognatha: Wien, Springer-Verlag, p. 4563.CrossRefGoogle Scholar
Erwin, D.H., and Valentine, J.W., 2013, The Cambrian Explosion: The Construction of Animal Biodiversity: Greenwood Village, Colorado, Roberts and Company, 406 p.Google Scholar
Erwin, D.H., Laflamme, M., Tweedt, S.M., Sperling, E.A., Pisani, D., and Peterson, K.J., 2011, The Cambrian conundrum: early divergence and later ecological success in the early history of animals: Science, v. 334, p. 10911097.Google Scholar
Goloboff, P., Farris, J.S., and Nixon, K., 2008, TNT, a free program for phylogenetic analysis: Cladistics, v. 24, p. 774786.Google Scholar
Han, J., Kubota, S., Uchida, H.-O., Stanley, G.D. Jr., Yao, X., Shu, D., Li, Y., and Yasui, K., 2010, Tiny sea anemone from the lower Cambrian of China: PLoS One, v. 5, p. e13276.Google Scholar
Han, J., Kubota, S., Li, G., Yao, X., Yang, X., Shu, D., Li, Y., Kinoshita, S., Sasaki, O., Komiya, T., and Yan, G., 2013, Early Cambrian pentamerous cubozoan embryos from South China: PLoS One, v. 8, p. e70741.Google Scholar
Han, J., Kubota, S., Li, G., Ou, Q., Wang, X., Yao, X., Shu, D., Li, Y., Uesugi, K., Hoshino, M., Sasaki, O., Kano, H., Sato, T., and Komiya, T., 2016a, Divergent evolution of medusozoan symmetric patterns: evidence from the microanatomy of Cambrian tetramerous cubozoans from South China: Gondwana Research, v. 31, p. 150163.Google Scholar
Han, J., Li, G.X., Kubota, S., Ou, Q., Toshino, S., Wang, X., Yang, X.G., Uesugi, K., Masato, H., Sasaki, O., Kano, H., Sato, T., and Komiya, T., 2016b, Internal microanatomy and zoological affinity of the early Cambrian Olivooides : Acta Geologica Sinica (English Edition), v. 90, p. 3865.Google Scholar
Han, J., Conway Morris, S., Ou, Q., Shu, D.G., and Huang, H., 2017, Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China): Nature, v. 542, p. 228231.Google Scholar
Harvey, T.H.P., Dong, X.-P., and Donoghue, P.C.J., 2010, Are palaeoscolecids ancestral ecdysozoans?: Evolution & Development, v. 12, p. 177200.Google Scholar
Haug, J.T., Maas, A., Waloszek, D., Donoghue, P.C.J., and Bengtson, S., 2009, A new species of Markuelia from the Middle Cambrian of Australia: Memoirs of the Association of Australasian Palaeontologists, v. 37, p. 303313.Google Scholar
He, T.G., and Xie, Y.S., 1989, Some problematic small shelly fossils from the Meishucunian of the lower Cambrian in the western Yangtze Region: Acta Micropalaeontologica Sinica, v. 6, p. 111127.Google Scholar
He, Y.X., and Yang, X.H., 1986, Early Cambrian coelenterates from Nanjiang, Sichuan: Bulletin of the Chengdu Institute of Geology and Mineral Resources, v. 7, p. 3143.Google Scholar
Hu, S.X., Li, Y., Luo, H., Fu, X.P., You, T., Pang, J.Y., Liu, Q., and Steiner, M., 2008, New records of palaeoscolecids from the early Cambrian of Yunnan, China: Acta Geologica Sinica (English Edition), v. 82, p. 244248.Google Scholar
Huldtgren, T., Cunningham, J.A., Yin, C., Stampanoni, M., Marone, F., Donoghue, P.C.J., and Bengtson, S., 2011, Fossilized nuclei and germination structures identify Ediacaran “animal embryos” as encysting protists: Science, v. 334, p. 16961699.Google Scholar
Jarms, G., 1991, Taxonomic characters from the polyp tubes of coronate medusae (Scyphozoa, Coronatae): Hydrobiologia, v. 216/217, p. 463470.Google Scholar
Li, P., Hua, H., Zhang, L., Zhang, D., Jin, X., and Liu, Z., 2007, Lower Cambrian phosphatized Punctatus from southern Shaanxi and their ontogeny sequence: Chinese Science Bulletin, v. 52, p. 28202828.Google Scholar
Li, Z., 1984, The discovery and its significance of small shelly fossils in Hexi area: Xixiang, Shaanxi, Geology of Shaanxi, v. 2, p. 7377.Google Scholar
Liu, Y., Li, Y., Shao, T., Zhang, H.Q., Wang, Q., and Qiao, J., 2014a, Quadrapyrgites from the lower Cambrian of South China: growth pattern, post-embryonic development, and affinity: Chinese Science Bulletin, v. 59, p. 40864095.Google Scholar
Liu, Y., Xiao, S., Shao, T., Broce, J., and Zhang, H.Q., 2014bThe oldest known priapulid-like scalidophoran animal and its implications for the early evolution of cycloneuralians and ecdysozoans: Evolution & Development, v. 16, p. 155165.Google Scholar
Liu, Y., Shao, T.Q., Zhang, H.Q., Wang, Q., Zhang, Y.N., Chen, C., Liang, Y.C., and Xue, J.Q., 2017, A new scyphozoan from the Cambrian Fortunian Stage of South China: Palaeontology, v. 60, p. 511518.Google Scholar
Maas, A., 2013, Gastrotricha, Cycloneuralia and Gnathifera: the fossil record, in Schmidt-Rhaesa, A., ed., Handbook of Zoology: Gastrotricha, Cycloneuralia and Gnathifera: Berlin, De Gruzyter, p. 1128.Google Scholar
Maas, A., Braun, A., Dong, X.-P., Donoghue, P.C.J., Müller, K.J., Olempska, E., Repetski, J.E., Siveter, D.J., Stein, M., and Waloszek, D., 2006, The ‘Orsten’—more than a Cambrian Konservat-Lagerstätte yielding exceptional preservation: Palaeoworld, v. 15, p. 266282.CrossRefGoogle Scholar
Maas, A., Waloszek, D., Haug, J.T., and Müller, K.J., 2007, A possible larval roundworm from the Cambrian ‘Orsten’ and its bearing on the phylogeny of Cycloneuralia: Memoirs of the Association of Australasian Palaeontologists, v. 34, p. 499519.Google Scholar
Miranda, L.S., Hirano, Y.M., Mills, C.E., Falconer, A., Fenwick, D., Marques, A.C., and Collins, A.G., 2016, Systematics of stalked jellyfishes (Cnidaria: Staurozoa): PeerJ, v. 4, p. e1951.Google Scholar
Missarzhevsky, V.V., 1973, Konodontoobraznye organizmy iz pogranichnykh sloev kembriya i dokembriya Sibirskoi platformy i Kazakhstana. [Conodont-shaped organisms from Precambrian–Cambrian boundary strata of the Siberian Platform and Kazakhstan]: Trudy Instituta Geologii i Geofiziki SO AN SSSR, v. 49, p. 5357.Google Scholar
Missarzhevsky, V.V., 1974, Novye dannye o drevneishikh okamenelostyakh rannego kembriya Sibirskoi platformy. [New data on the oldest fossils of the early Cambrian of the Siberian Platform], in Zhuravleva, I.T., and Rozanov, A.Y., eds., Biostratigrafiya i paleontologiya nizhnego kembriya Evropy i severnoi Azii. [Biostratigraphy and palaeontology of the Lower Cambrian of Europe and northern Asia]: Moscow, Nauka, p. 179189.Google Scholar
Müller, K.J., 1985, Exceptional preservation in calcareous nodules: Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences, v. 311, p. 6773.Google Scholar
Nielsen, C., 2012, Animal Evolution: Interrelationships of the Living Phyla: Oxford, Oxford University Press, 402 p.Google Scholar
Peng, S., Babcock, L.E., and Cooper, R.A., 2012, The Cambrian Period, in Gradstein, F.M., Ogg, J.G., Schmitz, M., and Ogg, G., eds., Geological Time Scale 2012: Oxford, Elsevier, p. 437488.Google Scholar
Peterson, K.J., Cotton, J.A., Gehling, J.G., and Pisani, D., 2008, The Ediacaran emergence of bilaterians: congruence between the genetic and geological fossil records: Philosophical Transactions of the Royal Society of London B Biological Sciences, v. 363, p. 14351443.Google Scholar
Qian, Y., 1977, Hyolitha and some problematica from the Lower Cambrian Meishucun Stage in central and southwestern China: Acta Palaeontologica Sinica, v. 16, p. 255275.Google Scholar
Qian, Y., and Bengtson, S., 1989, Palaeontology and biostratigraphy of the Early Cambrian Meishucunian Stage in Yunnan Province: South China, Fossils and Strata, v. 24, p. 1156.Google Scholar
Schmidt-Rhaesa, A., 1998, Phylogenetic relationships of the nematomorpha—a discussion of current hypotheses: Zoologischer Anzeiger, v. 236, p. 203216.Google Scholar
Shao, T.Q., Liu, Y.H., Wang, Q., Zhang, H.Q., Tang, H., and Li, Y., 2016, New material of the oldest known scalidophoran animal Eopriapulites sphinx : Palaeoworld, v. 25, p. 111.Google Scholar
Steiner, M., Li, G., Qian, Y., and Zhu, M., 2004a, Lower Cambrian Small Shelly Fossils of northern Sichuan and southern Shaanxi (China), and their biostratigraphic importance: Geobios, v. 37, p. 259275.Google Scholar
Steiner, M., Zhu, M., Li, G., Qian, Y., and Erdtmann, B.-D., 2004b, New Early Cambrian bilaterian embryos and larvae from China: Geology, v. 32, p. 833836.Google Scholar
Steiner, M., Li, G., Qian, Y., Zhu, M., and Erdtmann, B.-D., 2007, Neoproterozoic to early Cambrian small shelly fossil assemblages and a revised biostratigraphic correlation of the Yangtze Platform (China): Palaeogeography Palaeoclimatology Palaeoecology, v. 254, p. 6799.Google Scholar
Steiner, M., Qian, Y., Li, G., Hagadorn, J.W., and Zhu, M., 2014, The developmental cycles of early Cambrian Olivooidae fam. nov. (?Cycloneuralia) from the Yangtze Platform (China): Palaeogeography Palaeoclimatology Palaeoecology, v. 398, p. 97124.Google Scholar
Swofford, D.L., 2002, PAUP*. Phylogenetic Analysis Using Parsimony (*and other methods). Version 4: Sunderland, MA, Sinauer Associates.Google Scholar
Val’kov, A.K., 1983, Rasprostranenie drevneishikh skeletnykh organizmov i korrelyatsiya nizhnei granitsy kembriya v yugo-vostochnoi chasti Sibirskoi platformy [Distribution of the oldest skeletal organisms and correlation of the lower boundary of the Cambrian in the southeastern part of the Siberian Platform], in Khomentovsky, V.V., Yakshin, M.S., and Karlova, G.A., eds., Pozdnii dokembrii i rannii paleozoi Sibiri, Vendskie otlozheniya: SO AN SSSR, Novosibirsk, Institut Geologii i Geofiziki, p. 3748.Google Scholar
Val’kov, A.K., and Karlova, G.A., 1984, Fauna iz perekhodnykh vendsko-kembriiskikh sloev nizhnego techeniya r. Gonam. [The fauna of the transitional Vendian-Cambrian beds in the lower reaches of the River Gonam], in Khomentovsky, V.V., Shenfil, Y.Y., and Yashin, M.S., eds., Stratigrafiya pozdnego dokembriya i rannego paleozoya, Srednyaya Sibir: Novosibirsk, Institut Geologii i Geofiziki, p. 1241.Google Scholar
Van Iten, H., Zhu, M., and Li, G., 2010, Redescription of Hexaconularia He and Yang, 1986 (lower Cambrian, South China): implications for the affinities of conulariid-like small shelly fossils: Palaeontology, v. 53, p. 191199.Google Scholar
Voronova, L.G., and Missarzhevsky, V.V., 1969, Nakhodki vodoroskei i trubok chervei v pogranichnhkh sloyakh kembriya i dokembriya na1 severe Sibirskoi platformy. [Discovery of algae and worm tubes in the Precambrian-Cambrian boundary beds of the northern part of the Siberian Platform]: Doklady AN SSSR, v. 184, p. 207210.Google Scholar
Wennberg, S.A., Janssen, R., and Budd, G., 2009, Hatching and earliest larval stages of the priapulid worm Priapulus caudatus : Invertebrate Biology, v. 128, p. 157171.Google Scholar
Whittard, W.F., 1953, Palaeoscolex piscatorum gen. sp. nov., a worm from the Tremadocian of Shropshire: The Quarterly Journal of the Geological Society of London, v. 109, p. 125136.Google Scholar
Xiao, S., Zhang, Y., and Knoll, A.H., 1998, Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite: Nature, v. 391, p. 553558.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, v. 10, p. 1262.Google Scholar
Xue, Y., Zhou, C., and Tang, T., 1999, “Animal embryos”, a misinterpretation of Neoproterozoic microfossils: Acta Micropalaeontologica Sinica, v. 16, p. 14.Google Scholar
Yang, B., Steiner, M., Li, G., and Keupp, H., 2014, Terreneuvian small shelly faunas of East Yunnan (South China) and their biostratigraphic implications: Palaeogeography Palaeoclimatology Palaeoecology, v. 398, p. 2858.Google Scholar
Yang, X.H., and He, T.G., 1984, New small shelly fossils from lower Cambrian Meishucun Stage of Nanjiang Area, northern Sichuan: Professional Papers in Stratigraphy and Palaeontology, v. 13, p. 3547.Google Scholar
Yasui, K., Reimer, J.D., Liu, Y., Yao, X., Kubo, D., Shu, D., and Li, Y., 2013, A diploblastic radiate animal at the dawn of Cambrian diversification with a simple body plan: distinct from Cnidaria?: PLoS One, v. 8, p. e65890.Google Scholar
Yuan, X., Xiao, S., Parsley, R.L., Zhou, C., Chen, Z., and Hu, J., 2002, Towering sponges in an Early Cambrian Lagerstätte: disparity between nonbilaterian and bilaterian epifaunal tierers at the Neoproterozoic-Cambrian transition: Geology, v. 30, p. 363366.Google Scholar
Yue, Z., and Bengtson, S., 1999, Embryonic and post-embryonic development of the Early Cambrian cnidarian Olivooides : Lethaia, v. 32, p. 181195.Google Scholar
Zhang, H.Q., and Dong, X.-P., 2015, The oldest known larva and its implications for the plesiomorphy of metazoan development: Science Bulletin, v. 60, p. 19471953.Google Scholar
Zhang, H.Q., Xiao, S., Liu, Y.H., Yuan, X.L., Wan, B., Muscente, A.D., Shao, T.Q., Gong, H., and Cao, G., 2015, Armored kinorhynch-like scalidophoran animals from the early Cambrian: Scientific Reports, v. 5, p. 16521.Google Scholar
Zhu, M.Y., Zhuravlev, A.Y., Wood, R.A., and Sukhov, S.S., 2017, A deep root for the Cambrian explosion: implications of new bio- and chemostratigraphy from the Siberian Platform: Geology, v. 45, p. 459462.Google Scholar