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Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/taje20 The correlation between macroscopic algae and metazoans in the Ediacaran: a case study on the Wenghui biota in northeastern Guizhou, South China Y. Wanga, Y. Wangb, W. Duc & X. Wangb a School of Resources and Environments, Guizhou University, Guiyang 550025, PR China b School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China c Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153–8902, Japan Published online: 19 Sep 2014.
To cite this article: Y. Wang, Y. Wang, W. Du & X. Wang (2014) The correlation between macroscopic algae and metazoans in the Ediacaran: a case study on the Wenghui biota in northeastern Guizhou, South China, Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia, 61:7, 967-977, DOI: 10.1080/08120099.2014.956231 To link to this article: http://dx.doi.org/10.1080/08120099.2014.956231
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Australian Journal of Earth Sciences (2014) 61, 967 977, http://dx.doi.org/10.1080/08120099.2014.956231
The correlation between macroscopic algae and metazoans in the Ediacaran: a case study on the Wenghui biota in northeastern Guizhou, South China
Y. WANG1*, Y. WANG2,W.DU3 AND X. WANG2
1School of Resources and Environments, Guizhou University, Guiyang 550025, PR China. 2School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China. 3Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153 8902, Japan.
After the Marinoan glaciation, macroscopic organisms thrived in the Yangtze Sea, South China, during the Ediacaran period. The Wenghui biota, which is found from the upper Doushantuo Formation black shales (>551 Ma) in northeastern Guizhou, South China, includes macroscopic algae, metazoans and ichnofossils. Most macroalgae in the Wenghui biota bear a holdfast to secure them onto seafloor and have a thallus of various lengths extending into the water column. This biota can be divided into Globusphyton, Sectoralga Longifuniculum, Cucullus, Beltanelliformis and Baculiphyca Gesinella assemblages. A fossil-barren interval containing a thin layer of feldspathic sandstone separates the macroscopic organisms into two distinct parts. From the Globusphyton assemblage through the Sectoralga Longifuniculum assemblage to the Cucullus assemblage, metazoans show a positive correlation with the abundance and diversity of branching macroalgae at both metre and millimetre scales. Nevertheless, both Beltanelliformis and Baculiphyca Gesinella assemblages, in which the number and diversity of macroscopic algae and metazoans, especially the shorter branching macroalgae, are obviously decreasing or even lacking, might be related to a special environment and a fragile ecosystem. In addition, the ratios of Ni/Co, U/Th and V/(V C Ni) display zigzagged profiles at millimetre scales indicating frequent redox fluctuations. Variations in macrofossils and trace elements at both millimetre and metre scales indicate that the oxygen content in the northeast Guizhou Sea fluctuated frequently during the middle late Ediacaran period and the Wenghui biota possibly lived in the redox buffering zone. Moreover, the abundance and diversity of macroalgae, especially the branching macroalgae, could have significantly influenced the redox conditions in water column. The increase in oxygen may have improved the environment for the growth and reproduction of macroalgae and metazoans.
KEY WORDS: metazoan, macroalga, Wenghui biota, Ediacaran, northeastern Guizhou, South China.
INTRODUCTION in the Yangtze Sea during the Ediacaran period (Figure 1). Although there are still debates on the macro- After the Marinoan global glaciation (or the Nantuo gla- organismal classification, many researchers have ciation in China), global warming during the Ediacaran
Downloaded by [University of Tokyo] at 16:21 17 November 2014 reported that metazoans had emerged in the middle late may be an important condition for the development of Ediacaran period (Chen et al. 1994b, 2000; Ding et al. 1996; macroscopic organisms. In the Yangtze Block, South Xiao et al. 2002; Wang et al. 2007b, 2008, 2009, 2010, 2011; China, abundant macroscopic organisms were reported Wang & Wang 2008, 2011; Tang et al. 2008, 2011; Zhu et al. in Chinese Ediacaran macrobiotas, including the Lan- 2008). tian biota from the lower Lantian Formation in south- The carbonaceous compressions from the upper ern Anhui (e.g. Chen et al. 1994a; Tang et al. 1997; Yuan Doushantuo Formation in northeastern Guizhou were et al. 2011), the Miaohe biota from the upper Doushantuo reported first by Zhao et al. (2005) and named as the Wen- Formation in western Hubei (e.g. Zhu & Chen 1984; Chen ghui biota by Wang et al. (2007a). Wang et al. (2007a, b, & Xiao 1991, 1992; Chen et al. 1994b; Ding et al. 1996; Xiao 2008), Wang & Wang (2008, 2011), Tang et al. (2008) and et al. 2002) and the Wenghui biota from the upper Doush- Zhu et al. (2008) systemically described the macroscopic antuo Formation in northeastern Guizhou (e.g. Wang algae and metazoans in this biota. Based on fossil collec- et al. 2005, 2007a, 2008, 2009, 2011; Tang et al. 2009). These tion of the Wenghui biota at metre scales, Wang et al. Ediacaran macrobiotas, which are dominated by macro- (2011) reported the temporal sequences of assemblages. scopic algae, imply that macroscopic organisms thrived This paper discusses the relationship between
*Corresponding author: [email protected] Ó 2014 Geological Society of Australia TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
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Figure 1 Distribution of the Chinese Eidacaran macrobiotas in the Yangtze Block, South China. (a) Tectonic outline showing the location of Yangtze Block in China; and (b) paleogeographic reconstruction of the Yangtze Block during the early Edia- caran period (modified from Jiang et al. 2011).
macroscopic algae and metazoans in the Wenghui biota Macroscopic algae and metazoans at millimetre to metre scales. The abundance and diver- The macroscopic algae are the dominant fossils in the sity of macroscopic algae can influence the depositional Wenghui biota and can be morphologically divided into redox conditions, which in turn may affect the growth the (thallus- and filament-) branching macroalgae, the and reproduction of metazoans. unbranching macroalgae, the coin-shaped macroalgae and the macroalgal holdfasts. The thallus-branching THE WENGHUI BIOTA macroalgae include Anomalophyton zhangzhongyini Chen et al. 1994b (Figure 3a, b), Doushantuophyton line- The Wenghui biota includes macroscopic algae, metazo- area Chen in Chen & Xiao 1991 (Figure 3c), D. rigidulum ans and ichnofossils, and is found in the upper Doushan- Chen in Chen et al. 1994a (Figure 3d), Enteromorphites tuo Formation black shales in Wenghui Village, siniansis Zhu & Chen 1984 (Figure 3e), Jiangkouphyton Jiangkou County, northeastern Guizhou Province, guizhouensis Wang et al. 2007a (Figure 3f, g), Miaohephy- southern China (26 5000700N, 109 0102000E). In the Wenghui ton bifurcatum Chen in Chen & Xiao 1991 (Figure 3h), section, the Doushantuo Formation is about 71 m thick, Wenghuiphyton erecta Wang et al. 2007a (Figure 3i, j), overlying the Nantuo Formation diamictite and underly- Zhongbaodaophyton crassa Chen et al. 1994b (Figure ing the bedded cherts of the Liuchapo Formation. It com- 3k, l) and Z. robustus Wang et al. 2007a (Figure 3m). The prises dolostones in the lower part (cap carbonate), filament-branching macroalgae include Globusphyton dolostones and shaly dolostones with black shales in the lineare Wang et al. 2007a (Figure 3n, o), Longifuniculum middle part, and black shales with abundant carbona- dissolutum Steiner et al. 1992 (Figure 3p, q), Sectoralga Downloaded by [University of Tokyo] at 16:21 17 November 2014 ceous compressions (macroscopic fossils) in the upper typical Hu in Ding et al. 1996 (Figure 3t) and part (Figure 2). The well-preserved macrofossils, espe- S. wenghuiensis Wang et al. 2007a (Figure 3r, s). The cially the filamentous holdfasts of macroalgae, imply unbranching macroalgae include Baculiphyca taeniata that the Wenghui biota is mainly preserved in (or near) Yuan et al. 1995 (Figure 4a, b), Flabellophyton strigata situ (Wang et al. 2005, 2009, 2011). In addition, macro- Yuan et al. 1999 (Figure 4c, d), Gesinella hunanensis scopic algae are dominant in the Wenghui biota, imply- Steiner et al. 1992 (Figure 4e, f), Liulingjitaenia alloplecta ing that the Wenghui biota was living in a euphotic Chen & Xiao 1992 (Figure 4g, h), Sangshuania cf. sang- environment (Wang et al. 2005, 2007a, 2010, 2011; Jiang shuanensis Du in Du et al. 1986 (Figure 4i, j) and Sinocy- et al. 2011). lindra yunnanesis Chen & Erdtmann 1991 (Figure 4k). In the Yangtze Gorges area, western Hubei, the The coin-shaped macroalgae include Beltanelliformis Re Os age from the black shale at the bottom of the brunsae Menner in Keller et al. 1974 (Figure 4l, m) and upper Doushantuo Formation (Member IV) is 593 § 17 Chuaria circularis Walcott 1899 (Figure 4n, o). Various Ma (Zhu et al. 2013), and the U Pb zircon ages from the macroalgal holdfasts (Figure 4p s) in the Wenghui biota top Doushantuo Formation are 551.1 § 0.7 Ma (Condon are of unknown affinity. et al. 2005). The Doushantuo Formation in Wenghui and In addition, there are abundant metazoans in the Yangtze Gorges areas are roughly correlatable in macro- Wenghui biota. Eoandromeda octobrachiata Tang et al. fossil assemblages and lithology (Wang et al. 2007a, 2011; 2008 (Figure 5a c), a discoidal compression with eight Tang et al. 2009; Wang & Wang 2011; Jiang et al. 2011). spiral arms (Figure 5a, b) and many feather-like cilia on Considering the large uncertainty of the Re Os age, the the arms (Figure 5b, c), was regarded as a diploblastic Wenghui biota is inferred to be close to 551 Ma. metazoan (Tang et al. 2008; Zhu et al. 2008), or as TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
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Figure 2 Distribution of the Wenghui biota in the Doushantuo Formation from Wenghui section, northeastern Guizhou, South China. (a) Columnar section of the Doushantuo Formation; and (b) macrofossil distribution in the upper Doushantuo Formation.
ctenophores (Wang et al. 2008, 2009, 2011; Tang et al. 2009, cnidarians (Sprigg 1947; Sun 1986; Seilacher 1999; McCall 2011). Cyclomedusa cf. radiata Sprigg 1947 (Figure 5d f), 2006; Wang et al. 2008, 2011). Similarly, another large dis- a large-sized discoidal fossil with a central tubercle, con- coidal compression (Figure 5g), which displays tri-radial centric ridges and veins, and radiating veins (Figure 5f), symmetry, was believed to be a trilobozoan (Wang et al. was generally regarded to have an affinity with 2008, 2009, 2011), an extinct taxon of metazoan that was TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
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Figure 3 Branching macroalgae in the Ediacaran Wenghui biota from northeastern Guizhou, South China. (a, b) Anomalophy- ton zhangzhongyini Chen et al. 1994b, (a) specimen WH-P-04026B, (b) the detail view of (a), showing the opposite side-branchlets around the main axis; (c) Doushantuophyton linearea Chen in Chen & Xiao 1991, specimen WH-P-04241; (d) Doushantuophyton rigidulum Chen in Chen et al. 1994a, specimen WH-P-01078; (e) Enteromorphites siniansis Zhu & Chen 1984, specimen WH-P- 02082; (f, g) Jiangkouphyton guizhouensis Wang et al. 2007a, (f) specimen WH-P-04234A, (g) specimen WH-P-04234B, showing the bud-like patterns on the last branches; (h) Miaohephyton bifurcatum Chen in Chen & Xiao 1991, specimen WH49 0722; (i, j) Wenghuiphyton erecta Wang et al. 2007a, (i) specimen JK42 1101, (j) specimen JK42 1106; (k, l) Zhongbaodaophyton crassa Chen et al. 1994b, (k) specimen WH-P-03017, (l) specimen WH-P-03036; (m) Zhongbaodaophyton robustus Wang et al. 2007a, speci- men MH40 0653; (n, o) Globusphyton lineare Wang et al. 2007a, (n) specimen MH40 0730, (o) specimen MH40 0248; (p, q) Longi- funiculum dissolutum Steiner et al. 1992, (p) specimen WH-P-01045, (q) specimen WH-P-01059; (r, s) Sectoralga wenghuiensis Wang et al. 2007a, (r) specimen WH-P-01109, (s) specimen WH-P-02021; (t) Sectoralga typical Hu in Ding et al. 1996, specimen WH-P-04030. All specimens are preserved in Guizhou University,China.
reported in the Ediacara fauna from Australia and the elongated sac-shaped compression with a basic construct White Sea biota from Russia (Fedonkin 1985, 1990; Sei- but no mineralised spicules, was suggested to have an lacher 1999; Ivantsov & Fedonkin 2002; McCall 2006). affinity with macroscopic alga (Xiao et al. 2002; Cucullus fraudulentus Steiner 1994 (Figure 5h j), an Yuan et al. 2002; Finks & Rigby 2004). Alternatively, TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
Ediacaran Wenghui biota, South China 971 Downloaded by [University of Tokyo] at 16:21 17 November 2014 Figure 4 Unbranching and coin-shaped macroalgae and the macroalgal holdfasts in the Wenghui biota from northeastern Guizhou, South China. (a, b) Baculiphyca taeniata Yuan et al. 1995, (a) specimen WH-P-01130, (b) specimen MH50 1008; (c, d) Flabellophyton strigata Yuan et al. 1999, (c) specimen MH50 0163, (d) specimen WH-P-02040; (e, f) Gesinella hunanensis Steiner et al. 1992, (e) specimen WH-P-04267, (f) specimen MH50 0639; (g, h) Liulingjitaenia alloplecta Chen & Xiao 1992, (g) specimen WH-P-04005, (h) specimen MH50 0624; (i, j) Sangshuania cf. sangshuanensis Du in Du et al. 1986, (i) specimen WH59 0752, (j) specimen MH58 4242; (k) Sinocylindra yunnanesis Chen & Erdtmann 1991, specimen WH57 0741; (l, m) Beltanelliformis brunsae Menner in Keller et al. 1974, (l) specimen MH58-0029, (m) specimen JK-P-64005; (n, o) Chuaria circularis Walcott 1899, (n) specimen MH50 0669, (o) specimen WH-P-01055; (p s) macroalgal holdfasts, (p) specimen MH45 0151, (q) specimen MH45 1049, (r) specimen MH50 1017, (s) specimen MH50 0707. All specimens are preserved in Guizhou University,China.
C. fraudulentus was also interpreted as a metazoan possible ancestor of the conical shelled animal in the (Chen et al. 1994b; Ding et al. 1996; Wang et al. 2007a). Cambrian (Chen et al. 1994b) or a cnidaria (Xiao et al. Moreover, Wang & Wang (2011) and Wang et al. (2011) 2002). Having the conical outline, a thin wall (see Xiao noted that C. fraudulentus has organic walls (Figure 5h), et al. 2002, figure 7.12, 7.13), an outer-sinus opening complex non-mineralised spongin fibre networks (Figure 5l), transverse veins (Figure 5m, n) and a longitu- (Figure 5i, j), side openings and top pores (Figure 5j); dinal ridge with small bulges (Figure 5n), P. minor was thus C. fraudulentus was believed to be a demosponge interpreted as a non-mineralised shell metazoan charac- (Wang & Wang 2011; Wang et al. 2011). Protoconites minor terised by bilateral symmetry in morphology (Wang Chen et al. 1994b (Figure 5k n) was regarded as a et al. 2007b, 2011). In addition, Wenghuiia jiangkouensis TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
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Figure 5 Metazoans and ichnofossils in the Wenghui biota from northeastern Guizhou, South China. (a c) Eoandromeda octo- brachiata Tang et al. 2008, (a) specimen WH-A-02002, (b) specimen JK55-0025, (c) specimen WH-A-04023; (d f) Cyclomedusa cf. radiate Sprigg 1947, (d) specimen WH50 0708, (e) specimen WH-50-9001, (f) the detail view of (e), showing the central tubercle, concentric ridges and veins, and radiate veins; (g) Trilobozoan Fedonkin 1985, specimen MH50 9002; (h j) Cucullus fraudulen- tus Steiner 1994, (h) specimen WH-C-04054, (i) specimen WH-C-04114, (j) the detail view of (i), showing the top pores, side open- ings and complex non-mineralised sponin fibre networks; (k n) Protoconites minor Chen et al. 1994b, (k) specimen WH-M- 05037, (l) the detail view of (k), showing the outer-sinus opening and the thin wall, (m) specimen WH-M-04030, (n) the detail view of (m), showing the transverse veins and a longitudinal ridge with tumours; (o t) Wenghuiia jiangkouensis Wang & Wang 2008, (o) specimen WH-V-04140A, (p) the detail view of (o), (q) specimen WH-V-04140B, (r) the detail view of (q), (s) speci- men WH-V-04193, (t) specimen WH-V-06004B; (u, v) Linbotulichnus ichnosp., (u) specimen JK-03003, (v) specimen WH50-0021. AC, alimentary canal; CL, clitellum; ME, metamere; MO, mouth; SA, seta around anus; SB, seta on body; SP,seta on parapodia; PA, parapodia; WL, wall. All specimens are preserved in Guizhou University,China. TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
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Wang & Wang 2008 (Figure 5o t) has been compared assemblage (layer 9) is the first assemblage above the fos- with annelids in morphology and functional biology sil-barren layers 4 8. Although this Globusphyton assem- (Wang & Wang 2008; Wang et al. 2008, 2009, 2011), because blage is similar to the first one and has filament- it has an elongated, cylindrical body with many homolo- branching Globusphyton and abundant Sectoralga gous metameres (Figure 5o q, s, t), a mouth at the first ( 23.1%), it has clearly less unbranching macroalgae and segment (Figure 5p), an anus at the end of body more branching macroalgae (Wang et al. 2011). The small- (Figure 5r), a longer eleventh or twelfth segment possible sized conical Protoconites is the only metazoan in this for the clitellum (Figure 5p, s), some parapodia on the Globusphyton assemblage. Different from the lower ahead venter of the clitellum (Figure 5p, s), different setae assemblage sequence, the Sectoralga Longifuniculum around the anus and on all metameres and parapodia assemblage (layers 10 13) is in between Globusphyton and (Figure 5p, r t), and a line-like digestive system passing Cucullus assemblages. Compared with the Globusphyton through the centre of the entire body from mouth to anus assemblage, the diversity and abundance of both (Figure 5o r, t ). Linbotulichnus ichnosp., a taenioid com- branching macroalgae and metazoans increase in the pression meandering on the bedding planes (Figure 5u, Sectoralga Longifuniculum assemblage (Wang et al. 2011). v), was regarded as a putative trace fossil (Xiao et al. 2002; Metazoans and ichnofossils, including Eoandromeda, Pro- Wang et al. 2005; Tang et al. 2008), or ichnofossil (Ding toconites, Cyclomedusa and Linbotulichnus, appear in this et al. 1996; Wang et al. 2009, 2011). This fossil is interpreted assemblage. Above the Sectoralga Longifuniculum assem- as an ichnofossil made by a wriggling animal on the sedi- blage, the Cucullus assemblage (layers 14 20) is the most mentary surface on the basis of bead-shaped segments diverse assemblage, including all metazoans and thallus- with crescent-shaped spaces (Figure 5u, v). branching macroalgae in the Wenghui biota. Neverthe- less, some macroalgae (e.g. Enteromorphites, Miaohephy- ton, Sangshuania and Wenghuiphyton) and metazoans Distribution of macroscopic organisms in the (e.g. Cyclomedusa, Protoconites and trilobozoas) of the geological section Cucullus assemblage disappeared after the first emer- The Wenghui biota is collected from the »30 m-thick gence of the coin-shaped macroalga Beltanelliformis (layer black shales of the upper Doushantuo Formation in the 21). The number and diversity of macroscopic algae and Wenghui section, Jiangkou, northeastern Guizhou. At metazoans decrease greatly from layer 21 to the top of the metre scales, the collecting and counting results of mac- upper Doushantuo Formation. In the Beltanelliformis roscopic fossils indicate that the distribution of macro- assemblage (layers 21 25), Beltanelliformis emerges in organisms displays a difference in diversity and abun- layer 21, develops in layers 22 and 23, then is significantly dance (Figure 2). According to this difference, Wang enriched ( 84.5%) and rapidly disappears in layer 25 et al. (2011) divided the Wenghui biota into five assemb- (Wang et al. 2011). In this assemblage, macroscopic algae lages: (1) the Globusphyton assemblage, characterised by are mainly elongated macroalgae (e.g. Baculiphyca, Gesi- abundant shorter macroalgae (e.g. Globusphyton, Sector- nella, Liulingjitaenia, Longifuniculum and Sinocylindra), alga) and rare metazoans; (2) the Cucullus assemblage, and the branching macroalgae and metazoans are clearly marked by the occurrence of Cucullus, and by abundant decreased. Metazoans in this assemblage only include and diverse branching macroalgae and metazoans; Protoconites, Cucullus, Wenghuiia and the maker of Linbo- (3) the Sectoralga Longifuniculum assemblage, with tulichnus. In addition, some macroscopic algae (e.g. Anom- components from both Globusphyton and Cucullus alophyton, Chuaria, Doushantuophyton, Longfengshania assemblages, but containing neither Globusphyton nor and Sectoralga) and most metazoans except for the long Cucullus; (4) the Beltanelliformis assemblage, character- sac-like Cucullus are absent in the Beltanelliformis assem- ised by the unusual abundance and dense aggregates of blage. After the disappearance of Beltanelliformis,the Beltanelliformis; and (5) the Baculiphyca Gesinella Baculiphyca Gesinella assemblage appears in layers Downloaded by [University of Tokyo] at 16:21 17 November 2014 assemblage, characterised by the abundance of Baculi- 26 31. The Baculiphyca Gesinella assemblage has the phyca and Gesinella, without Beltanelliformis. No macro- lowest abundance and diversity, and has some elongated fossils were collected in layers 4 8; a 15 cm-thick macro-organisms, including the unbranching macroalgae feldspathic sandstone is found in layer 7. The fossil- (e.g. Baculiphyca, Gesinella and Sinocylindra), branching barren layers (layers 4 8) separate the macroscopic macroalgae (e.g. Liulingjitaenia and Zhongbaodaophyton) organisms into two distinct parts (Figure 2b). and metazoan (only Cucullus). Three dominant genera The lower part (layers 1 3) has only the Globusphyton Baculiphyca, Gesinella and Cucullus range between 22.2 and Cucullus assemblages. The Globusphyton assem- and 62.5%, 12.5 and 62.5%, and 4.2 and 12.5%, respectively blage (layer 1), the first macro-assemblage, has abundant (Wang et al. 2011); the three genera together make up filament-branching macroalgae (>39.7%), especially the 79.2% of the fossil contents. Remarkably, no macrofossils shorter macroalga Sectoralga (counting over 20.9%), the arefoundinlayer24(intheBeltanelliformis assemblage) relative sparsity of thallus-branching and unbranching or layers 28, 29 and 31 (in the Baculiphyca Gesinella macroalgae, and rare metazoans (e.g. Eoandromeda and assemblage). Protoconites) and ichnofossil Linbotulichnus (Wang et al. Generally, the macroscopic fossils in the upper 2011). In the subsequent Cucullus assemblage (layers 2 Doushantuo Formation are found in black shales and 3), metazoans are much more diversified, including alternating with relatively light-coloured shales. At Eoandromedas, Cucullus, Cyclomedus, Protoconite and millimetre scale, macrofossils in black shales are signifi- trilobozoas. cantly more abundant than that in light-coloured shales, In the upper part (layers 9 31), all five assemblages of and metazoans are generally found together with abun- the Wenghui biota are present. The Globusphyton dant macroalgae (Figure 6b, c). TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:32
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Figure 6 Geochemical profiles from the samples scaled off shales at mm scale. (a) The m-level columnar section; (b) the mm- level columnar sections; (c) the number of macrofossils; (d) the Ni/Co profiles; (e) U/Th profiles; and (f) V/(V C Ni) profiles.
For trace-element analysis, 19 samples, including spectrometer (ICP-MS). Ratios of redox-sensitive trace fossil-rich black shales and fossil-poor light-coloured metals [e.g. Ni/Co, U/Th and V/(V C Ni)] display shales, were collected in different macrofossil assemb- millimetre-scale zigzagged patterns across the layers. lages (layers 1, 11, 15 and 18). Dried powders (<200 Fossil-rich black shales generally have higher Ni/Co mesh) of all fresh samples were dissolved to make sam- and U/Th ratios (Figure 6d, e)orlowerV/(VC Ni) val- ple solutions and then analysed on a Finnigan MAT ues (Table 1; Figure 6f) than fossil-poor light-coloured ELEMENT inductively coupled plasma source mass shales.
Table 1 Analytical data on redox-sensitive trace metals.
Layer Depth (mm) Macrofossil V (mg/g) Co (mg/g) Ni (mg/g) Th (mg/g) U (mg/g) Ni/Co U/Th V/(V C Ni)
18-5 29 41 Rare 182 1.20 4.70 9.49 4.93 3.918 0.519 0.9748
Downloaded by [University of Tokyo] at 16:21 17 November 2014 18-4 20 29 Abundant 128 0.74 3.23 10.15 6.88 4.363 0.677 0.9754 18-3 15 20 Rare 178 1.26 4.49 9.81 5.24 3.567 0.535 0.9754 18-2 6 15 Abundant 160 0.71 4.29 9.82 7.57 6.040 0.771 0.9739 18-1 0 6 Rare 130 0.36 2.70 7.02 4.23 4.285 0.602 0.9797 15-6 36 43 Abundant 177 1.29 3.90 12.31 6.51 3.024 0.529 0.9784 15-5 30 36 Rare 166 1.22 3.37 11.51 5.88 2.763 0.511 0.9801 15-4 26 30 Abundant 171 1.31 4.31 11.40 6.15 3.293 0.539 0.9754 15-3 11 26 Abundant 162 1.15 3.81 11.74 6.28 3.313 0.535 0.9770 15-2 4 11 Rare 151 0.98 2.53 11.37 6.04 2.583 0.531 0.9853 15-1 0 4 Abundant 158 1.11 3.47 11.09 5.94 3.130 0.536 0.9878 11-3 35 57 Abundant 199 0.64 4.59 11.22 7.65 7.164 0.682 0.9775 11-2 29 35 Rare 248 0.77 3.33 13.58 9.13 4.238 0.672 0.9867 11-1 0 29 Abundant 291 0.91 10.44 14.96 11.03 11.468 0.737 0.9654 1-5 28 33 Rare 159 0.51 1.81 10.85 6.23 3.546 0.574 0.9888 1-4 24 28 Abundant 160 0.52 2.07 12.08 7.41 3.974 0.614 0.9872 1-3 21 24 Rare 144 0.48 1.78 10.39 5.84 3.713 0.562 0.9878 1-2 4 21 Abundant 139 0.48 2.53 9.71 5.66 5.274 0.583 0.9821 1-1 0 4 Rare 133 0.48 1.77 9.84 5.46 3.686 0.555 0.9868 TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:33
Ediacaran Wenghui biota, South China 975
DISCUSSION metazoans depend on macroalgae for oxygen and food sources, directly and indirectly. In the Ediacacran Wenghui biota, the changes in abun- The redox-sensitive trace metals are used as an indi- dance and diversity of macro-organisms at both metre cator for the paleoredox conditions during the deposi- and millimetre scales indicate that metazoans have a tion of mudstones. The ratios of Ni/Co and U/Th have a positive correlation with macroscopic algae. positive correlation with the oxygen content in sedimen- During the middle late Ediacaran period, the Globu- tary environment, whereas V/(V C Ni) has a negative sphyton assemblage (layer 1) was the first assemblage correlation (Jones & Manning 1994; Rimmer 2004; Zart- colonised in the northeast Guizhou Sea. The macroalgal man & Richardson 2005; Guo et al. 2007; Schroder€ & Grot- genus Globusphyton with circular oval nodes serving as zinger 2007; Cuney 2010). In the upper Doushantuo holdfast was interpreted as a benthic macroalga living Formation at Wenghui, the zigzagged profiles of redox- on the sediment surface (Wang et al. 2007a, 2011). Differ- sensitive trace metals in the millimetre-scale sections ent from microbial mats, the Globusphyton assemblage (Figure 6c, d) indicate that the oxygen content in sedi- may have lived in microenvironments where the most mentary environment was higher in the fossil-poor light- macroscopic algae were anchored by their holdfast on coloured shales. In other words, the oxygen content and the seafloor and extended through thallus into the sea- redox condition in the Northeast Guizhou Sea fluctuated water column. Macroalgae with a longer thallus can get during the middle late Ediacaran period. Previous geo- more sunlight for photosynthesis. Subsequently, the chemical studies in the Yangtze Gorges area suggested Cucullus assemblage (layers 2 and 3) with abundant met- that the upper Doushantuo Formation black shales azoans replaced the Globusphyton assemblage and occu- (Member IV) were deposited in a euxinic (anoxic and sul- pied this area. Metazoans in this assemblage show a fidic) water column (Scott et al. 2008;Liet al. 2010), but positive correlation with the abundance of branching the Miaohe biota from the Member IV black shales macroalgae. The Cucullus assemblage is followed by fos- includes numerous benthic macro-organisms (e.g. Chen sil-barren layers (layers 4 8) with a 15 cm-thick feld- et al. 1994b; Ding et al. 1996; Xiao et al. 2002) that require spathic sandstone in layer 7 considered to be the result oxygen (Runnegar 1982;Loganet al. 1995). Logan et al. of a sudden drop in sea-level or a current event from the (1995) suggested a stratified ocean to reconcile the con- land (Wang et al. 2011). The sedimentary event may tradictory between paleontological and geochemical imply a significant hiatus or stratigraphic truncation data. The frequent redox and fossil-abundance fluctua- and cause the fossil-barren interval to halt the develop- tions at the Wenghui section imply that the Wenghui ment of macro-organism assemblages. biota possibly lived in the redox-buffering zone, and the After the sedimentary event, the Globusphyton assem- changes in oxygen may influence the number of macro- blage (in layer 9) recolonised this area. The subsequent fossils. The carbonaceous compressions formed by the Sectoralga Longifuniculum assemblage (layers 10 13) non-mineralised macro-organismal bodies may be better has abundant shorter macroalga Sectoralga but no Glob- preserved in anoxic euxinic deposits. usphyton, and more abundant and diverse metazoans The emergence of Beltanelliformis (layer 21) may be an but no Cucullus. Above the Sectoralga Longifuniculum event in the development of the macro-organismal assemblage, the Cucullus assemblage (layers 14 20) has assemblages. From the Beltanelliformis assemblage to the the most abundant and diverse macroalgae and metazo- Baculiphyca Gesinella assemblage (layers 21 25), macro- ans. Most of the macroalgae and all metazoans are found fossils (especially branching macroalgae and metazoans) in this assemblage. From the Globusphyton assemblage significantly decreased, and no macrofosil was found in to the Cucullus assemblage, there is an increase in the layers 24, 28, 29 and 31. In the Beltanelliformis assemblage abundance and diversity of branching macroalgae as (layers 26 31), the coin-shaped compression Beltanellifor- well as in the diversity of metazoans. In addition, the dis- mis went through emergence, enormous abundance and Downloaded by [University of Tokyo] at 16:21 17 November 2014 tribution of macroscopic organisms at a millimetre scale disappearance; a large amount of macroalgae and meta- shows that metazoans are correlated with the number of zoans disappeared in this assemblage. The coin-shaped B. macroalgae (Figure 6c). In the Ediacaran, the emergence brunsae is densely distributed, but few overlapped with of macroalgae with various lengths, especially the each other on the bedded surface (Figure 4l, m). For this increase in branching macroalgae, imply that the compe- reason, it was generally interpreted as a benthic rather tition among macroalgae for solar energy and other than planktonic macroalga (Chen et al. 1994a, 2000; Xiao resources intensified to advance their photosynthesis et al. 2002; Yuan et al. 2002; Wang et al. 2007a; 2009, 2011). and accelerate the release of oxygen. Runnegar (1982) The dominance of benthic Beltanelliformis may have estimated that Dichinsonia, a bilateral metazoan among excluded many macro-organisms, except for the shorter the Ediacaran fauna from South Australia, might sur- macro-organisms. Therefore, the Beltanelliformis assem- vive in oxygen levels at 6 10% of the present atmo- blage may reflect special or harsh environments. Simi- spheric level. Wenghuiia of the Wenghui biota implies larly,the Baculiphyca Gesinella assemblage has only five that the aerobic metazoan had emerged in the Ediacaran longer macroalga genera (Baculiphyca, Gesinella, Liuling- (Wang et al. 2011). In addition, Wenghuiia, with a line- jitaenia, Longifuniculum and Zhongbaodaophyton) and an like digestive system from mouth to anus and motorial elongated benthic porifer Cucullus, but no shorter macro- organs (e.g. metamere, parapodia), is likely to be a algae were found. Moreover, no macrofossil was found in mobile and energy-expansive metazoan, rather than a layers 28, 29 and 31 in the Baculiphyca Gesinella assem- chemosymbiotic metazoan proposed by Seilacher (1989). blage. Compared with the Beltanelliformis assemblage, Thus, the positive correlation between macroalgae and the subsequent Baculiphyca Gesinella assemblage metazoans in the Wenghui biota implies that the early records a fragile ecosystem. TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:33
976 Y. Wang et al.
CONCLUSIONS early metazoan life. In:SIMONETTA A. M. & CONWAY MORRIS S. eds. The Early Evolution of Metazoa and the Significance of Problem- The Wenghui biota, including abundant macroscopic atic Taxa,pp.57 76. Cambridge University Press, Cambridge. algae, metazoans and ichnofossils, are found from the CHEN M. E. & XIAO Z. Z. 1991. Discovery of the macrofossils in the upper Sinian Doushantuo Formation at Miaohe, eastern Yangtze upper Doushantuo Formation black shales (593 551 Ma) Gorges. Scientia Geologica Sinica 4,317 324. of the Ediacaran in northeastern Guizhou, South China. CHEN M. E. & XIAO Z. Z. 1992. Macrofossil biota from upper Sinian This biota can be divided into Globusphyton, Sectoralga Doushantuo Formation in eastern Yangtze Gorges, China. Acta Longifuniculum, Cucullus, Beltanelliformis and Palaeontologica Sinica 31, 513 529. Baculiphyca Gesinella assemblages. The development of CHEN M. E., CHEN Q. Y. & XIAO Z. Z. 2000. Preliminary discussion on the early evolutionary history of macroscopic plants. Scientia Geolog- macro-organism assemblage was separated into two ica Sinica 35,1 15. stages by a sedimentary event that formed a thin-bedded CHEN M. E., LU G. Y. & XIAO Z. Z. 1994a. Preliminary study on the algal feldspathic sandstone within a fossil-barren interval. macrofossils: Lantian flora from the Lantian Formation of Upper From the Globusphyton assemblage to the Cucullus Sinian in southern Anhui. Bulletin of Institute of Geology, Acade- mia Sinica 7, 252 267. assemblage, the abundance and diversity of macroscopic CHEN M. E., XIAO Z. Z. & YUAN X. L. 1994b. A new assemblage of mega- algae and metazoans, especially the branching macroal- fossils-Miaohe Biota from upper Sinian Doushantuo Formation, gae, increase at metre scale, and metazoans show a posi- Yangtze gorges. Acta Palaeontologica Sinica 33,392 403. tive correlation with the abundance of macroalgae at CONDON D., ZHU M., BOWRING S., WANG W. , Y ANG A. & JIN Y. 2005. U Pb millimetre scale. The different lengths of macroalgae ages from the Neoproterozoic Toushantuo Formation, China. Sci- ence 308,95 98. and the increase in branching macroalgae imply that CUNEY M. 2010. Evolution of uranium fractionation processes the competition among macro-organisms for solar through time: driving the secular variation of uranium deposit energy was intensified in the northeast Guizhou Sea types. Economic Geology 105,553 569. during the Ediacaran period. The intensified competi- DING L. F., LI Y. , H U X. W., XIAO Y. P. , S U C. Q. & HUANG J. C. 1996. Sinian Miaohe Biota,pp.1 208. Geological Publishing House, Beijing. tion among macroalgae advanced their photosynthesis DU R. L., TIAN L. F. & LI H. B. 1986. Discovery of megafossils in the and accelerated the release of oxygen that were favour- Gaoyuzhuang Formation of the Changchengian System, Jixian. able for the growth and reproduction of metazoans. In Acta Geologica Sinica 59, 115 120. addition, the zigzagged profiles of Ni/Co, U/Th and V/(V FEDONKIN M. A. 1985. Precambrian metazoans: the problems of preser- C Ni) ratios indicate frequent redox fluctuations at milli- vation, systematics and evolution. Philosophical Transactions of the Royal Society of London 311,27 45. metre scales. Higher ratios of Ni/Co and U/Th and a FEDONKIN M. A. 1990. Systematic description of Vendian Metazoa. In: lower ratio of V/(V C Ni) are generally found in macro- SOKOLOV B. S. & IVANOVSKIJ A. B. eds. The Vendian System: Palaeon- fossil-rich black shales, and there is a positive correla- tology, v. 1,pp.71 120. Springer-Verlag, Berlin. tion between oxygen content and abundance of macro- FINKS R. M. & RIGBY J. K. 2004. Paleozoic demosponges. In:KAESLER R. L. ed. Treatise on Invertebrate Paleontology, Part E (Revised), organisms at the millimetre scale. The frequent redox Porifera 3,pp.9 173. The Geological Society of America and Uni- and fossil-abundance fluctuations imply that the Wen- versity of Kansas, Boulder, Colorado, and Lawrence, Kansas. ghui biota possibly lived in a redox-buffering zone, and GUO Q., SHIELDS G. A., LIU C., STRAUSS H., ZHU M., PI D., GOLDBERG T. & changes in oxygen content influenced the number of pre- YANG X. 2007. Trace element chemostratigraphy of two served marcofossils. Ediacaran Cambrian successions in South China: implications for organosedimentary metal enrichment and silicification in In both Beltanelliformis and Baculiphyca Gesinella the Early Cambrian. Palaeogeography, Palaeoclimatology, assemblages, the number of macro-organisms was signif- Palaeoecology 254, 194 216. icantly reduced, but the abundance of longer unbranch- JIANG G., SHI X., ZHANG S., WANG Y. & X IAO S. 2011. Stratigraphy and ing macroalgae is increased, associated with a decrease paleogeography of the Ediacaran Doushantuo Formation (ca. 635 551 Ma) in South China. Gondwana Research 19,831 849. or absence of shorter branching macroalgae and metazo- JONES B. J. & MANNING D. A. C. 1994. Comparison of geochemical indi- ans. In addition, no macrofossils were found in several ces used for the interpretation of palaeoredox condition in layers. Both Beltanelliformis and Baculiphyca Gesinella ancient mudstones. Chemical Geology 111,111 129.
Downloaded by [University of Tokyo] at 16:21 17 November 2014 assemblages might reflect a special or harsh environ- IVANTSOV A. Y. & FEDONKIN M. A. 2002. Conulariid-like fossil from the ment, implying a fragile ecosystem. Vendian of Russia: a metazoan clade across the Proterozoic/ Palaeozoic boundary. Palaeontology 45, 1219 1229. KELLER B. M., MENNER V. V. , S TEPANOV V. A . & C HUMAKOV T.N. 1974. New finds of fossils in the Precambrian Valday Series along the ACKNOWLEDGEMENTS Syuzma River. Izverstia Akademii Nauk SSSR, Seriya Geologiche- skaya 12, 130 134. This research is supported by the National Science LI C., LOVE G. D., LYONS T. W. , F IKE D. A., SESSIONS A. L. & CHU X. 2010. A Foundation of China (Grant No. 41162003 and No. stratified redox model for the Ediacaran ocean. Science 328, 41172002), the Science and Technology Foundation of 80 83. Guizhou Province, China (Grant No. J-2010-2030) and the LOGAN G. A., HAYES J. M., HIESHIMA G. B. & SUMMONS R. E. 1995. Termi- nal Proterozoic reorganization of biogeochemical cycles. Nature Foundation of Guizhou Provincial Governor. The 376,53 56. authors thank Prof. S. Y. Gu of Guizhou University and MCCALL G. J. H. 2006. The Vendian (Ediacaran) in the geological Prof. D. Z. Chen, of Chinese Academy of Sciences, for the record: Enigmas in geology’s prelude to the Cambrian explosion. redox-sensitive trace-element analysis; and the anony- Earth-Science Reviews 77,1 229. mous reviewers for their constructive comments that RIMMER S. M. 2004. Geochemical paleoredox indicators in Devon- ian Mississippian black shales, Central Appalachian Basin improved this manuscript greatly. (USA). Chemical Geology 206,373 391. RUNNEGAR B. 1982. Oxygen requirements, a biology and phylogenetic significance of the late Precambrian worm Dickinsonia and the REFERENCES evolution of the burrowing habit. Alcheringa 6,223 239. SCHRODER€ S. & GROTZINGER J. P. 2007. Evidence for anoxia at the Edia- € CHEN J. & ERDTMANN B.-D. 1991. Lower Cambrian fossil Lagerstatte caran Cambrian boundary: the record of redox-sensitive trace from Chengjiang, Yunnan, China: Insights for reconstructing TAJE_A_956231.3d (TAJE) (210£274mm) 01-10-2014 11:33
Ediacaran Wenghui biota, South China 977
elements and rare earth element in Oman. Journal of the Geologi- source rocks in the Yangtze area. Sedimentary Geology and cal Society, London 164,175 187. Tethyan Geology 30,30 38. SCOTT C., LYONS T. W., B EKKER A., SHEN Y. , P OULTON S. W., CHU X. & ANBAR WANG Y. , W ANG X. L. & HUANG Y. M. 2007a. Macroscopic algae from the A. D. 2008. Tracing the stepwise oxygenation of the Proterozoic Ediacaran Doushantuo Formation in Northeastern Guizhou, ocean. Nature 452, 456 459. South China. Earth Science 32,828 844. SEILACHER A. 1989. Vendozoa: organismic construction in the Protero- WANG Y. , W ANG X. L. & HUANG Y. M. 2007b. Discussion on the classifica- zoic biosphere. Lethaia 22,229 239. tion and ecology of Protoconites from the Ediacaran Doushantuo SEILACHER A. 1999. Biomat-related lifestyles in the Precambrian. Pal- Formation in South China. Earth Science 32,41 50. aios 14,86 93. WANG Y. , W ANG X. L. & HUANG Y. M. 2008. Megascopic symmetrical met- SPRIGG R. C. 1947. Early Cambrian (?) jellyfish from the Flinders azoans from the Ediacaran Doushantuo Formation in the north- Ranges, South Australia. Transctions of the Royal Society of South eastern Guizhou, South China. Journal of China University of Australia 71,212 223. Geosciences 19, 200 206. STEINER M. 1994. Die neoproterozoishen Megaalgen Sudchinas. Ber- WANG Y. , Z HAO M. S., YANG Y. F. & W ANG X. L. 2009. Emergence of liner Geowissrnschaftliche Abhandlungen 15(E), 1 146. marco-organismal ecosystem of the Late Doushantuoian of the STEINER M., ERDTMANN B.-D. & CHEN J. 1992. Preliminary assessment of Ediacaran in South China, and its significances. Journal of new Late Sinian (Late Proterozoic) large siphonous and filamen- Palaeogeography 6, 640 650. tous “megaalgae” from eastern Wulingshan, north-central XIAO S., YUAN X., STEINER M. & KNOLL A. H. 2002. Macroscopic carbona- Hunan, China. Berliner Geowissenschaftliche Abhandlungen 3(E), ceous compressions in a terminal Proterozoic shale: a systematic 305 319. reassessment of the Miaohe biota, South China. Journal of Pale- SUN W. G. 1986. Precambrian medusoids: the Cyclomedusa piexus and ontology 76,347 376. Cyclomedusa-like pseudofossils. Precambrian Research 31,325 360. YUAN X., CHEN Z., XIAO S., ZHOU C. & HUA H. 2011. An early Ediacaran TANG F. , B ENGTSON S., WANG Y. , W ANG X. & YIN C. 2011. Eoandromeda assemblage of macroscopic and morphologically differentiated and the origin of Ctenophora. Evolution and Development 13, eukaryotes. Nature 470,390 393. 408 414. YUAN X., LI J. & CAO R. 1999. A diverse metaphyte assemblage from the TANG F. , Y IN C., BENGTSON S., LIU P. , W ANG Z. & GAO L. 2008. Octoradiate Neoproterozoic black shales of South China. Lethaia 32,143 155. Spiral Organisms in the Ediacran of South China. Acta Geologica YUAN X. L., LI J. & CHEN M. E. 1995. Development and their fossil Sinica 82,27 34. records of metaphytes from Late Precambrian. Acta Palaeonto- TANG F. , Y IN C.Y. & GAO L. Z. 1997. A new data of metaphyte fossils logica Sinica 34,90 102. from the Late Sinian Doushantuo Stage at Xiuning, Anhui Prov- YUAN X. L., XIAO S. H., YIN L. M., KNOLL A. H., ZHOU C. M. & MU X. N. ince. Acta Geologica Sinica 71, 289 296. 2002. Doushantuo Fossils: Life on the Eve of Animal Radiation, TANG F. , Y IN C. Y., LIU P. J. , G AO L. Z. & WANG Z. Q. 2009. Neoproterozoic pp. 26 40. University of Science and Technology of China Press, macrofossil records in South China and biostratigraphic succes- Hefei. sions and correlations. Acta Geoscientica Sinica 30,505 522. ZARTMAN R. E. & RICHARDSON S. H. 2005. Evidence from kimberlitic WALCOTT C. D. 1899. Precambrian fossiliferous formations. Bulletin of zircon for a decreasing mantle Th/U and implications for the Pre- the Geological Society of America 10,199 244. cambrian nitrogen cycle. Geobiology 4,285 297. WANG Y. & W ANG X. 2008. Annelid from the Neoproterozoic Doushan- ZHAO Y. L . , H E M. H., CHEN M. E., PENG J., YU M. Y., WANG Y. , YANG R. J., tuo Formation in the Northeast Guizhou, China. Acta Geologica WANG P. L . & Z HANG Z. H. 2005. The discovery of a Miaohe-type Sinica 82,257 265. biota from the Neoproterozoic Doushantuo Formation in Jiang- WANG Y. & W ANG X. 2011. New observations on Cucullus Steiner from kou County, Guizhou Province, China. Chinese Science Bulletin the Neoproterozoic Doushantuo Formation of Guizhou, South 49, 1916 1918. China. Lethaia 44, 275 286. ZHU B., BECKER H., JIANG S.-Y., PI D., FISCHER-GODDE€ M. & YANG J.-H. 2013. WANG Y. , C HEN H. D., WANG X. L. & HUANG Y.M. 2011. Research on suc- Re Os geochronology of black shales from the Neoproterozoic cession of the Ediacaran Doushantuoian meta-community in Doushantuo Formation, Yangtze Platform, South China. Northeast Guizhou, South China. Acta Geologica Sinica 85, Precambrian Research 225,67 76. 533 543. ZHU M., GEHLING J. G., XIAO S., ZHAO Y. & D ROSER M. L. 2008. Eight- WANG Y. , H E M. H., YU M. Y., ZHAO Y. L . , P ENG J., YANG Y. J. & Z HANG Z. H. armed Ediacara fossil preserved in contrasting taphonomic win- 2005. Preliminary discussion on ecological characteristics and dows from China and Australia. Geology 36,867 870. buried environments of Miaohe-type Biota during the Late ZHU W. Q . & C HEN M. E. 1984. On the discovery of macrofossil algae Doushantuoian of Sinian in northeastern Guizhou Province. from the late Sinian in the eastern Yangtze Gorges, South China. Journal of Palaeogeography 7, 328 335. Acta Botanica Sinica 26,558 560. WANG Y. , L EI L. F., CHEN H. D. & HOU M. C. 2010. Development of the Ediacaran (Sinian) multicellular organisms and formation of the Received 1 September 2013; accepted 16 August 2014 Downloaded by [University of Tokyo] at 16:21 17 November 2014