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Morphometric analysis of stem-group mollusks from the northern Yangtze Craton, China

Published online by Cambridge University Press:  27 May 2022

Yanchun Pang*
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com>
Michael Steiner
Affiliation:
College of Earth Science and Engineering, Shandong University of Science and Technology, Qianwangang Road 579, Qingdao 266590, China Department of Earth Sciences, Freie Universität Berlin, Malteserstrasse 74-100, Haus D, Berlin 12249, Germany
Ben Yang
Affiliation:
MNR Key Laboratory of Stratigraphy and Palaeontology, Institute of Geology, Chinese Academy of Geological Sciences, Baiwanzhuang street 26, Beijing 100037, PR China
Mingcai Hou
Affiliation:
State Key Laboratory of Oil Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China
James G. Ogg
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com> State Key Laboratory of Oil Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China Deprtment of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907 USA
Wenhu Ji
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com>
Qiang Hu
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com>
Siyu Liang
Affiliation:
College of Earth Science, Chengdu University of Technology, Chengdu 610059, China
Mengshao Zhang
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com>
Yangjian He
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com>
Li Lin
Affiliation:
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China <1490340577@qq.com> <374755906@qq.com> <823494913@qq.com> <2466019744@qq.com>
*
*Corresponding author

Abstract

Cap-shaped skeletal fossils are the earliest undisputed body fossils of mollusks appearing in the basal Cambrian. A study on the morphometry of cap-shaped fossils from the Nanjiang area (North Sichuan, China) is undertaken to understand the origin and evolution of the early mollusks. The distribution of these fossil cap-shaped mollusks indicates a stepwise increase in their diversity during the early Cambrian. Maikhanella Zhegallo in Voronin et al., 1982 co-occuring with the spinose sclerites of siphogonuchitids, is regarded as the earliest scleritized mollusk. It is followed by other maikhanellids, e.g., Purella Missarzhevsky, 1974 and Yunnanopleura Yu, 1987, which co-occur with the earliest univalved helcionellids, e.g., Igorella Missarzhevsky in Rozanov et al., 1969. Cluster analysis of their morphometric characteristics shows that the Maikhanella group is similar to the Purella and Yunnanopleura groups, but is less comparable with univalved helcionellids. The maikhanellids are interpreted as representatives of the stem group Aculifera, although it remains uncertain if one or two larger cap-shaped shell plates were present on the elongate slug-like body, comparable to those of Halkieria Poulsen, 1967 or Orthrozanclus Conway Morris and Caron, 2007. Maikhanellids are characterized by the prominent protrusions or scales on the cap-shaped shell plates arranged in a concentric pattern around the shell apex. Evolutionarily, the protrusions or scales are reduced in younger strata, whereas subsequently a typically concentric ornament developed, the cap-shaped shell plates developed higher profiles, and the apical region became increasingly bare of scales. Meanwhile, the cap-shaped shell plates gradually evolved into a helcionellid-like appearance with an anteroposteriorly inclined apex. The morphological evolution of the earliest sclerotized mollusks reflects biotic evolution and environmental adaption among the stem-group mollusks during the early Cambrian.

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Articles
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Copyright © The Author(s), 2022. Published by Cambridge University Press on behalf of The Paleontological Society

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References

Bengtson, S., 1992, The cap-shaped Cambrian fossil Maikhanella and the relationship between coeloscleritophorans and molluscs: Lethaia, v. 25, p. 401420.CrossRefGoogle Scholar
Billings, E., 1871, On some new species of Palaeozoic fossils: Canadian Naturalist, v. 6, p. 213233, 240.Google Scholar
Chen, Y., and Zhang, S., 1980, [Small shelly fossils from the early lower Cambrian, Sonlingpo, eastern Yangtze Gorges]: Geological Review, v. 26, no. 3, p. 190197. [in Chinese]Google Scholar
Chen, Y.L., Chu, X.L., Zhang, X.L., and Zhai, M.G., 2016, Secondary phosphatization of the earliest Cambrian Small Shelly Fossil Anabarites from southern Shaanxi: Journal of Earth Science, v. 27, p. 196203, https://doi.org/10.1007/s12583-016-0691-7.CrossRefGoogle Scholar
Conway Morris, S., 1976, A new Cambrian lophophorate from the Burgess Shale of British Columbia: Palaeontology, v. 19, p. 199222.Google Scholar
Conway Morris, S., 1995, Enigmatic shells, possibly halkieriid, from the middle Cambrian Burgess Shale, British Columbia: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, v. 195, p. 319331.CrossRefGoogle Scholar
Conway Morris, S., and Caron, J.B., 2007, Halwaxiids and the early evolution of the lophotrochozoans: Science, v. 315, p. 12551258, https://doi.org/10.1126/science.1137187.CrossRefGoogle Scholar
Devaere, L., Clausen, S., Steiner, M., Javier, A.J., and Vachard, D., 2013, Chronostratigraphic and palaeogeographic significance of an early Cambrian microfauna from the Heraultia Limestone, northern Montagne Noire, France: Palaeontologia Electronica, v. 16, p. 191, https://doi.org/10.26879/366.Google Scholar
Ding, L.F., Zhang, L.Y., Li, Y., and Dong, J.S., 1992, [The Study of the Late Sinian-Early Cambrian Biota from the Northern Margin of Yangtze Platform]: Beijing, Scientific and Technical Documents Publishing House, 156 p. [in Chinese with English abstract]Google Scholar
Esakova, N.V., and Zhegallo, E.A., 1996, [Biostratigraphy and Fauna of Lower Cambrian of Mongolia]: Moscow, Science Press, 209 p. [in Russian]Google Scholar
Feng, W.M., Sun, W.G., and Qian, Y., 2001, [Skeletalization characters, classification and evolutionary signification of early Cambrian monoplacophoran maikhanellids]: Acta Palaeontologica Sinica, v. 40, p. 195213. [in Chinese with English abstract]Google Scholar
Guo, J.F., Li, Y., and Li, G.X., 2014, Small shelly fossils from the early Cambrian Yanjiahe Formation, Yichang, Hubei, China: Gondwana Research, v. 25, p. 9991007, https://doi.org/10.1016/j.gr.2013.03.007.CrossRefGoogle Scholar
Hamdi, B., Brasier, M.D, and Jiang, Z.W., 1989, Earliest skeletal fossils from Precambrian-Cambrian boundary strata, Elburz Mountains: Geological Magazine, v. 126, p. 283289.CrossRefGoogle Scholar
He, T.G., and Yang, X.H., 1982, Lower Cambrian Meishucun stage of western Yangtze stratigraphic region and its small shelly fossils: Bulletin of the Chengdu Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences, v. 3, p. 6995.Google Scholar
Huang, B., Harper, D.A.T., Hammer, Ø., 2013, Introduction to PAST, a comprehensive statistics software package for paleontological data analysis: Acta Palaeontological Sinica, v. 52, no. 2: 161181.Google Scholar
Jacquet, S.M., and Brock, G.A., 2016, Lower Cambrian helcionelloid macromolluscs from South Australia: Gondwana Research, v. 36, p. 333358, https://doi.org/10.1016/j.gr.2015.06.012.CrossRefGoogle Scholar
Jacquet, S.M., Brock, G.A., and Paterson, J.R., 2014, New data on Oikozetetes (Mollusca, Halkieriidae) from the lower Cambrian of South Australia: Journal of Paleontology, v. 88, p. 10721084, https://doi.org/10.1017/S0022336000057668.CrossRefGoogle Scholar
Ji, W.H., Pang, Y.C., Wen, Y., and Hu, Q., 2019, [Tubular fossil shells: Composition and their relationship with surrounding rocks in the Terreneuvian series at the Laoheba section in Mabian Phosphate deposit area, South Sichuan]: Acta Micropalaeontologica Sinica, v. 36, p. 309318. [in Chinese with English abstract]Google Scholar
Jiang, Z.W., 1980, [Monoplacophorans and gastropods fauna of the Meishucun stage from the Meishucun section, Yunnan]: Acta Geological Sinica, v. 2, p. 112126. [in Chinese with English abstract]Google Scholar
Kerber, M., 1988, Microfossils from lower Cambrian rocks of the Montagen Noire, France: Palaeontographica, A, Palaeozoologie-Stratigraphie, v. 202, p. 127203.Google Scholar
Kouchinsky, A., 1999, Shell microstructures of the Early Cambrian Anabarella and Watsonella as new evidence on the origin of the Rostroconchia: Lethaia, v. 32, p. 173180.CrossRefGoogle Scholar
Kouchinsky, A., Bengtson, S., Runnegar, B., Skovsted, C.B., Steiner, M., and Vendrasco, M., 2012, Chronology of early Cambrian biomineralization: Geological Magazine, v. 149, p. 221251, https://doi.org/10.1017/S0016756811000720.CrossRefGoogle Scholar
Kouchinsky, A., Bengtson, S., Landing, E., Steiner, M., Vendrasco, M., and Ziegler, K., 2017, Terreneuvian stratigraphy and faunas from the Anabar Uplift, Siberia: Acta Palaeontologica Polonica, v. 62, p. 311440, https://doi.org/10.4202/app.00289.2016.CrossRefGoogle Scholar
Li, G.X., Steiner, M., Zhu, X.J., Yang, A.H., Wang, H.F., and Erdtmann, B.D., 2007, Early Cambrian metazoan fossil record of South China: Generic diversity and radiation patterns: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 254, p. 229249, https://doi.org/10.1016/j.palaeo.2007.03.017.Google Scholar
Liu, D.Y., 1979, [Earliest Cambrian brachiopods from southwest China]: Acta Palaeontologica Sinica, v. 18, p. 505511. [in Chinese]Google Scholar
Liu, Y.H., Zhang, Y.N., Shao, T.Q., Tang, H.H., Jiang, K.T., Wang, Q., Cheng, C., Dong, J.Y., Liang, Y.C., Dai, J., and Xue, J.Q., 2016, New maikhanellid shells and siphogonuchitid spicule bundles from the Cambrian Fortunian stage of South China: Acta Geologica Sinica (English Edition), v. 90, p. 16291636, https://doi.org/10.1111/1755-6724.12806.CrossRefGoogle Scholar
Luo, H.L., Jiang, Z.W., Wu, X.C., Song, X.L., and Ouyang, L., 1982, [The Sinian-Cambrian boundary in eastern Yunnan, China]: Kunming, China, People's Publishing House, 265 p. [in Chinese with English abstract]Google Scholar
Luo, H.L., Jiang, Z.W., Wu, X.C., Song, X.L., Ouyang, L., Xing, Y.S., and Tao, Y.H., 1984, [Sinian-Cambrian Boundary Stratotype Section at Meishucun, Jinning, Yunnan, China]: Kunming, Yunnan, China, People's Publishing House, 63 p. [in Chinese with English abstract]Google Scholar
Maloof, A.C., Porter, S.M., Moore, J.L., Dudsas, F.Ö., Bowing, S.A., Higgins, J.A., Fike, D.A., and Eddy, M.P., 2010, The earliest Cambrian record of animals and ocean geochemical change: Geological Society of America Bulletin, v. 122, p. 17311774, https://doi.org/10.1130/B30346.1.CrossRefGoogle Scholar
Missarzhevsky, V.V., 1973, [Conodont-shaped organisms from Precambrian and Cambrian boundary strata of the Siberian Platform and Kazakhstan], in Zhuraleva, I.T., ed., Palaeontological and Biostratigraphical Problems in the Lower Cambrian of Siberia and the Far East: Novosibirsk, Russia, Nauka Publishing House, p. 5357, pls. 9, 10. [in Russian]Google Scholar
Missarzhevsky, V.V., 1974, [New data on the oldest early Cambrian fossils of the Siberian Platform], in Zuravleva, I.T., and Rozanov, A.U., eds., Biostratigraphy and Paleontology of Lower Cambrian of Europe and Northern Asia: Moscow, Nauka, p. 179189. [in Russian]Google Scholar
Ogg, J.G., 2019, Integrated global stratigraphy and geologic timescales, with some future directions for stratigraphy in China: Earth-Science Reviews, v. 189, p. 620, https://doi.org/10.1016/j.earscirev.2018.01.001.CrossRefGoogle Scholar
Pang, Y.C., Lin, L., Ma, Y.Q., and Huang, Y.H., 2010, [Analysis of ore-bearing potential in the boundary line of Sinian-Cambrian System in the Nanjiang area of Northeast Sichuan, China]: Journal of Chengdu University of Technology (Science & Technology Edition), v. 37, p. 599604. [in Chinese with English abstract]Google Scholar
Pang, Y.C., Wang, X.B., and Lin, L., 2017a, [Ancient Marine Environment on the Eve of Small Shelly Fauna Radiation in the Northern Margin of the Upper Yangtze Platform]: Beijing, Science Press, 105 p. [in Chinese]Google Scholar
Pang, Y.C., Steiner, M., Shen, C., Feng, M.S., Lin, L., and Liu, D.K., 2017b, Shell composition of Terreneuvian tubular fossils from north-east Sichuan, China: Palaeontology, v. 60, p. 1526, https://doi.org/10.1111/pala.12268.CrossRefGoogle Scholar
Parkhaev, P.Y., 2004, New data on the morphology of shell muscles in Cambrian helcionelloid mollusks: Paleontological Journal, v. 51, p. 91112.Google Scholar
Parkhaev, P.Y., 2008, The early Cambrian radiation of Mollusca, in Ponder, W.F., and Lindberg, D.R.R., eds., Phylogeny and Evolution of the Mollusca: Berkeley, University of California Press, p. 3369.CrossRefGoogle Scholar
Parkhaev, P.Y., 2014, Structure of shell muscles in the Cambrian gastropod genus Bemella (Gastropoda: Archaeobranchia: Helcionellidae): Paleontological Journal, v. 48, p. 1725, https://doi.org/10.1134/S0031030114010092.CrossRefGoogle Scholar
Parkhaev, P.Y., 2017, Origin and the early evolution of the phylum Mollusca: Paleontological Journal, v. 51, p. 91112, https://doi.org/10.1134/S003103011706003X.CrossRefGoogle Scholar
Parkhaev, P.Y., and Demidenko, Yu.E., 2010, Zooproblematica and Mollusca from the lower Cambrian Meishucun Section (Yunnan, China), and taxonomy and systematics of the Cambrian small shelly fossils of China: Paleontological Journal, v. 44, p. 8831161, https://doi.org/10.1134/S0031030110080010.CrossRefGoogle Scholar
Paterson, J.R., Brock, G.A., and Skovsted, C.B., 2009, Oikozetetes from the early Cambrian of South Australia: Implications for halkieriid affinities and functional morphology: Lethaia, v. 42, p. 199203, https://doi.org/10.1111/j.1502-3931.2008.00132.x.Google Scholar
Ponder, W.F., Parkhaev, P.Y., and Beechey, D.L., 2007, A remarkable similarity in scaly shell structure in early Cambrian univalved limpets (Monoplacophora; Maikhanellidae) and a Recent fissurellid limpet (Gastropoda: Vetigastropoda) with a review of Maikhanellidae: Molluscan Research, v. 27, p. 153163.Google Scholar
Poulsen, C., 1967, Fossils from the lower Cambrian of Bornholm: Det Kongelige Danske Videnskabernes Selskab, Matematisk-Fysiske Meddelelser, v. 36, no. 2, p. 148.Google Scholar
Qian, Y., 1977, [Hyolitha and some Problematica from the lower Cambrian Meishucun Stage in central and S.W. China: Palaeontologica Sinica, v.16, p. 255275. [in Chinese with English abstract]Google Scholar
Qian, Y., 1978, [The early Cambrian hyolithids in central and southwest China and their stratigraphical significance]: Memoirs of Nanjing Institute of Geology and Paleontology, v. 11, p. 143. [in Chinese with English abstract]Google Scholar
Qian, Y., 1989, Early Cambrian small shelly fossils of China with special reference to the Precambrian-Cambrian boundary, in Stratigraphy and Palaeontology of Systemic Boundaries in China: Precambrian-Cambrian Boundary, Volume 2: Nanjing: Nanjing University Publishing House, p. 1341.Google Scholar
Qian, Y., 1999, [Taxonomy and Biostratigraphy of SSF in China]: Beijing, Science Press, 247 p. [in Chinese with English abstract]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
Qian, Y., and Yin, G.-Z., 1984, [Zhijinitidae and its stratigraphical significance]: Acta Paleontologica Sinica, v. 23, p. 215223. [in Chinese]Google Scholar
Qian, Y., Chen, M., and Chen, Y.Y., 1979, Hyolithids and other small shelly fossils from the lower Cambrian Huangshandong Formation in the eastern part of the Yangtze Gorge: Acta Palaeontologica Sinica, v. 18, no. 3, p. 207230.Google Scholar
Qin, J.C., Liu, Y.H., Liu, M.J., Zhang, H., Zhang, Y.N., Wang, Q., Shao, T.Q., Wu, X.T., Gao, Z.L., and Zhang, X., 2019, Maikhanellid and siphogonuchitids from the Cambrian Xixiang Lagerstätten in Southern Shaanxi, China: Acta Micropalaeontologica Sinica, v. 36, p. 3044.Google Scholar
Romanenko, E.V., 1968, [Cambrian 597 sponges of the order Heteractinellida in the Altay]: Paleontologicheskiy Zhurnal, v. 2, p. 134137. [in Russian]Google Scholar
Rozanov, A.Y., and Missarzhevsky, V.V., 1966, [Biostratigraphy and fauna of the lower horizons of the Cambrian]: Trudy Geologicheskogo Instituta Akademiya Nauk SSSR, v. 148, p. 1127. [in Russian]Google Scholar
Rozanov, A.Y., Missarzhevsky, V.V., Volkova, N.A., Voronova, L.C., Krylov, I.N., Keller, B.M., Korolyuk, I.K., Lendzion, K., Michniak, R., Pykhova, N.G., and Sidarov, A.D., 1969, [Tommotian stage and the Cambrian lower boundary problem]: Trudy Geolocheskogo Instituta Akademia Nauk SSSR, v. 206, p. 1298. [in Russian]Google Scholar
Shao, T.Q., Wang, Q., Liu, Y.H., Tang, H.H., Li, Y., Zheng, P.L., Zhu, C.Y., Liu, F.T., Qin, J., He, H.H., and Liu, S.Y., 2015, [The study on the maikhanellids in the Meishucun Stage from Xixiang Southern Shanxi Province, NW China]: Acta Micropalaeotologica Sinica, v. 32, p. 329338. [in Chinese with English abstract]Google Scholar
Steiner, M., Li, G.X., Qian, Y., and Zhu, M.Y., 2004, Lower Cambrian small shelly fossils of northern Sichuan and southern Shanxi (China), and their biostratigraphic importance: Geobios, v. 37, p. 259275, https://doi.org/10.1016/j.geobios.2003.08.001.CrossRefGoogle Scholar
Steiner, M., Li, G.X., Qian, Y., Zhu, M.Y., 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, https://doi.org/10.1016/j.palaeo.2007.03.046.CrossRefGoogle Scholar
Steiner, M., Yang, B., Hohl, S., Zhang, L., and Chang, S., 2020, Cambrian small skeletal fossil and carbon isotope records of the southern Huangling Anticline, Hubei (China) and implications for chemostratigraphy of the Yangtze Platform: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 554, p. 109817, https://doi.org/10.1016/j.palaeo.2020.109817.CrossRefGoogle Scholar
Steiner, M., Yang, B., Hohl, S., Li, D., and Donoghue, P., 2021, Exceptionally preserved early Cambrian bilateral developmental stages from Mongolia: Nature Communications, v, 12, p. 1037, https://doi.org/10.1038/s41467-021-21264-7.CrossRefGoogle Scholar
Vendrasco, M.J., and Checa, G., 2015, Shell microstructure and its inheritance in the calcite helcionellid Mackinnonia: Estonian Journal of Earth Sciences, v. 64, p. 99104, https://doi.org/10.3176/earth.2015.18.CrossRefGoogle Scholar
Vendrasco, M.J., Li, G.X., Porter, S.M., and Femandez, C.Z., 2009, New data on the enigmatic Ocruranus-Eohalobia group of early Cambrian small skeletal fossils: Palaeontology, v. 52, p. 13731396, https://doi.org/10.1111/j.1475-4983.2009.00913.x.CrossRefGoogle Scholar
Vendrasco, M.J., Porter, S.M., Kouchinsky, A.V., Li, G.X., and Fernandez, C.Z., 2010, New data on molluscs and their shell microstructures from the middle Cambrian Gowers Formation, Australia: Palaeontology, v. 53, p. 97135, https://doi.org/10.1111/j.1475-4983.2009.00922.x.CrossRefGoogle Scholar
Vendrasco, M.J., Checa, A.G., and Kouchinsky, A.V., 2011, Shell microstructure of the early bivalve Pojetaia and the independent origin of nacre within the Mollusca: Palaeontology, v. 54, p. 825850, https://doi.org/10.1111/j.1475-4983.2011.01056.x.CrossRefGoogle Scholar
Vinther, J., 2015, Frontiers in palaeontology—The origins of Molluscs: Palaeontology, v. 58, p. 1934, https://doi.org/10.1111/pala.12140.CrossRefGoogle Scholar
Vinther, J., Parry, L., Briggs, D.E.G., and Van Roy, P.V., 2017, Ancestral morphology of crown-group molluscs revealed by a new Ordovician stem aculiferan: Nature, v. 542, p. 471474, https://doi.org/10.1038/nature21055.CrossRefGoogle ScholarPubMed
Voronin, Y.I., Voronova, L.G., Grigor'eva, N.V., Drozdova, N.A., Zhegallo, E.A., Zhuravlev, A.Y., Ragozina, A.L., Rozanov, A.Y., Sayutina, T.A., Sysoev, V.A., and Fonin, V.D., 1982, [The Precambrian-Cambrian boundary in the geosynclinal regions (reference section Salany-Gol, MNR)]: Trudy Socmesinoj Soreisko-Mongol'skoj Paleontologicheskoj Chkspeditsii, v. 18, p. 1150. [in Russian]Google Scholar
Voronova, L.G., and Missarzhevsky, V.V., 1969, [Finds of algae and worm tubes in the Precambrian-Cambrian boundary beds of the northern part of the Siberian Platform]: Proceedings of the USSR Academy of Sciences, v. 184, p. 207210. [in Russian]Google Scholar
Vostokova, V.A., 1962, [Cambrian gastropods of the Siberian Platform and Taimyr]: Sbornik Rabot po Paleontologii i Stratigrafii, v. 28, p. 5174. [in Russian]Google Scholar
Wade, M., 1972, Hydrozoa and Scyphozoa and other medusoids from the Precambrian Ediacara fauna, South Australia: Palaeontology, v. 15, p. 197225.Google Scholar
Walcott, C.D., 1911, Middle Cambrian annelids: Cambrian geology and paleontology, II: Smithsonian Miscellaneous Collections, v. 57, p. 109144.Google Scholar
Xing, Y.S., Ding, L.F., Luo, H.L., He, T.G., and Wang, Y.G., 1983, [The Sinian-Cambrian boundary of China]: Bulletin of the Institute of Geology, Chinese Academy of Geological Sciences, v. 10, p. 1268 p. [in Chinese with English abstract]Google Scholar
Yang, B., Steiner, M., Li, G.X., and Keupp, H., 2014, Terreneuvian small shelly faunas of East Yunnan (South China) and their biostratigraphic implications: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 398, p. 2858, https://doi.org/10.1016/j.palaeo.2013.07.003.CrossRefGoogle Scholar
Yang, X.H., and He, T.G., 1984, [New small shelly fossils from lower Cambrian Meishucun Stage of Nanjiang area, northern Sichuan]: Stratigraphic Paleontological Collection, v. 13, p. 3547. [in Chinese with English abstract]Google Scholar
Yin, J.C., Ding, L.F., He, T.G., Li, S.L., and Shen, L.J., 1980, [The Sinian Stratigraphy Biology and Sedimentary Environment in Emei-Ganluo of Sichuan]: Chengdu, China, Sichuan People Press, 18 p. [in Chinese with English abstract]Google Scholar
Yu, W., 1974, Cambrian hyoliths, in Handbook of the Stratigraphy and Palaeontology of Southwest China: Beijing, Science Press, p. 111113.Google Scholar
Yu, W., 1979, [Earliest Cambrian monoplacophorans and gastropods from western Hubei with their biostratigraphical significance]: Acta Palaeontologica Sinica, v. 18, p. 233266. [in Chinese with English abstract]Google Scholar
Yu, W., 1987, [Yangtze micromolluscan fauna in Yangtze region of China with notes on the Precambrian-Cambrian boundary], in Stratigraphy and Palaeontology of Systemic Boundaries in China: Precambrian-Cambrian Boundary, Volume 1: Nanjing, Nanjing University Publishing House, p. 19344. [in Chinese with English abstract]Google Scholar
Yu, W., 2014, On the Yangtzeconus priscus-Archaeospira ornata assemblage (Mollusca) of the earliest Cambrian of China: Acta Geologica Sinica, v. 88, p. 12621287, https://doi.org/10.1111/1755-6724.12288.CrossRefGoogle Scholar
Zhao, F.C., Smith, M.R., Yin, Z.J., Zeng, H., Li, G.X., and Zhu, M.X., 2017, Orthrozanclus elongata n. sp. and the significance of sclerite-covered taxa for early thochozoan evolution: Scientific Reports, v. 7, p. 16232, https://doi.org/10.1038/s41598-017-16304-6.Google Scholar
Zhou, B., and Xiao, L., 1984, Early Cambrian monoplacophorans and gastropods from Huainan and Huoqiu counties, Anhui Province: Professional Papers in Stratigraphy and Palaeontology, v. 13, p. 125140.Google Scholar
Zhu, M.Y., Qian, Y., Jiang, Z.W., and He, T.G., 1996, [A preliminary study on the preservation, shell composition and microstructures of Cambrian SSF]: Acta Micropaleotologica Sinica, v. 13, p. 241254. [in Chinese with English abstract]Google Scholar
Zhu, M.Y., Yang, A.H., Yuan, J.L., Li, G.X., Zhang, J.M., Zhao, F.C., Ahn, S.Y., and Miao, L.Y., 2019, Cambrian integrative stratigraphy and timescale of China: Science China Earth Sciences, v. 62, p. 2560, https://doi.org/10.1007/s11430-017-9291-0.CrossRefGoogle Scholar