Wang et al.—Ediacaran disc-like holdfast


1093


2014 Macroalgal holdfast [gen. et sp. indet.] Wang et al., fig. 4p.


2014 Gesinella [sp. indet.] Steiner et al., 1992; Tang et al., fig. 2.2.


2014 Discoidal holdfast [gen. et sp. indet.] Wang et al., figs. 5A, B.


Etymology.—After the village of Wenghui in Jiangkou County, northeastern Guizhou Province, South China, in where abun- dant macroscopic fossils are collected.


Material.—57 specimens from the Wenghui section in north- eastern Guizhou, South China.


Types.—Holotype,WH50-1460 (Fig. 3.1); Paratypes, WH-P-5014 (Fig. 3.2) and JK48-0031 (Fig. 4.1, 4.2).


Diagnosis.—As for genus.


Figure 2. Drawing of the principal structures of Discusphyton wenghuiensis n. gen. n. sp.


1972; Duan and Lin, 1980; Fedonkin, 1982; Glaessner, 1984; Sun, 1986; Seilacher, 1992, 1999; Farmer et al., 1992; De, 2003; McCall, 2006; Zhang et al., 2006; Serezhnikova, 2007; Tang et al., 2008b; Wang et al., 2008, 2011, 2012a, 2016a). Tang et al. (2014) considered that the macroalgal holdfasts, that had fallen off the thallus and been preserved independently, were similar to or possibly mistaken as the disc-like metazoan. Discusphyton n. gen. differs from these Ediacaran metazoans in its discoid-like compression with smooth face and unbranching thallus, without concentric or radiating structure.


Discusphyton wenghuiensis new genus new species Figures 2, 3.1–3.11, 4.1–4.9


2005 Macroalgal holdfast [gen. et sp. indet.] Wang et al., fig. 4.10.


2006 Macroalgal holdfast [gen. et sp. indet.] Wang et al., pl. 2, fig. j.


2007 Unnamed holdfast forms [gen. et sp. indet.] Wang et al., p. 836, pl. 2, fig. 23.


2008a Macroalgal holdfast [gen. et sp. indet.] Tang et al., pl. 1, fig. 12.


2008a Gesinella hunanensis Steiner et al., 1992; Tang et al., pl. 2, fig. 19.


2009 Baculiphyca sp. Wang et al., fig. 2.2.


2009 Macrooscopic alga fossil [gen. et sp. indet.] Tang et al., fig. 2g.


2013 Discoidal rhizoid of macroalga [gen. et sp. indet.] Cheng et al., fig. 1.3.


Description.—Carbonaceous compression having a disc-like holdfast and an unbranching algal thallus (Fig. 3). The disc-like holdfast consists of a discoidal rhizoid and a globular rhizome. The discoidal rhizoid, with smooth surface and edge, typically is preserved in the bedding planes as a circular carbonaceous film or mass that commonly has nonuniform density, gradually lighting in color from the center to the edge (Figs. 3.1–3.3, 3.5, 3.11, 4.1, 4.3, 4.5–4.9). In a small number of specimens, it is preserved as a half-circle (Fig. 3.6–3.10) in which two arc-shaped edges are observed (Figs. 3.7, 4.8), which appear to be folded discoidal rhizoids. The globular rhizome, a globular structure within the discoidal rhizoid, is expanded by the thallus substrate and bears a smooth surface (Fig. 3.1, 3.2, 3.6). The carbonaceous density of the globular rhizome is thicker than that of the discoidal rhizoid, forming an obvious border between them (Fig. 3.1, 3.2, 3.6, 3.11). On the surface of the discoidal rhizoid center, it generally has a more or less rounded hump (Figs. 3.3–3.5, 3.7–3.11, 4.2, 4.6–4.8), possibly formed by the globular rhizome. The unbranching clavate thallus is incom- pletely preserved. The lower part of thallus, a terete stipe, is three-dimensionally preserved (Fig. 3.1–3.5, 3.7–3.10), with smallest diameter at the primal stipe (connection between stipe and rhizome) and increasing gradually upwards in diameter (Fig. 3). Connecting with the stipe, the compressed lamina (upper part of thallus) is a rapidly expanded portion (Fig. 3.6, 3.7, 3.9), but not observed the completely preserved lamina. In some specimens that thallus has fallen off, a circular cross sec- tion of the stipe remains on the center of the discoidal rhizoid (Fig. 4). A shallow, ring-shaped depression surrounding the primal stipe is present on the surface of the discoidal rhizoid (Fig. 4.1, 4.2, 4.5–4.9). The discoidal rhizoid is 3.0–14.9mm in diameter. The longest preserved thallus is 14.6mm. The globular rhizome is 0.6–2.9mm in diameter. The stipe is 3.4– 9.7mm in length and 1.7mm in the preserved maximum dia- meter. The lamina is 17.4mm and 4.1mm in the preserved maximum length and maximum width, respectively. The growth rates of the stipe width and the lamina width per unit length (= [difference between maximumand minimum widths]/ [length between two measuring points] ×100%) are 0.9–9.2% and 12.9–25.4%, respectively.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204  |  Page 205  |  Page 206  |  Page 207  |  Page 208  |  Page 209  |  Page 210  |  Page 211  |  Page 212  |  Page 213  |  Page 214  |  Page 215  |  Page 216  |  Page 217  |  Page 218  |  Page 219  |  Page 220  |  Page 221  |  Page 222  |  Page 223  |  Page 224  |  Page 225  |  Page 226  |  Page 227  |  Page 228  |  Page 229  |  Page 230  |  Page 231  |  Page 232  |  Page 233  |  Page 234  |  Page 235  |  Page 236  |  Page 237  |  Page 238  |  Page 239  |  Page 240  |  Page 241  |  Page 242  |  Page 243  |  Page 244  |  Page 245  |  Page 246  |  Page 247  |  Page 248  |  Page 249  |  Page 250  |  Page 251  |  Page 252  |  Page 253  |  Page 254  |  Page 255  |  Page 256  |  Page 257  |  Page 258  |  Page 259  |  Page 260  |  Page 261  |  Page 262  |  Page 263  |  Page 264  |  Page 265  |  Page 266  |  Page 267  |  Page 268  |  Page 269  |  Page 270  |  Page 271  |  Page 272  |  Page 273  |  Page 274  |  Page 275  |  Page 276