Journal of Paleontology, 92(6), 2018, p. 972–981 Copyright © 2018, The Paleontological Society 0022-3360/15/0088-0906 doi: 10.1017/jpa.2018.41


Paleoecological Significance of Complex Fossil Associations of the Eldonioid Pararotadiscus guizhouensis with other Faunal Members of the Kaili Biota (Stage 5, Cambrian, South China)


Yuanlong Zhao,1 Mingkun Wang,1 Steven T. LoDuca,2 Xinglian Yang,1 Yuning Yang,1 Yujuan Liu,1 and Xin Cheng3


1College of Resource and Environmental Engineering, Guizhou University, Guiyang, Guizhou 550025, China ⟨zhaoyuanlong@126.com⟩,


⟨mkwang1986@163.com⟩, ⟨yangxinglian2002@163.com⟩, ⟨ynyang333@163.com⟩, ⟨liuyujuan0102@163.com⟩ 2Department of Geography and Geology, Eastern Michigan University, Ypsilanti, Michigan, 48197, USA ⟨sloduca@emich.edu⟩ 3Institute of Vertebrate Paleontology and Paleoanthropology, China Academy of Sciences, Beijing 100044, China ⟨cheng_xin1982@126.com⟩


Abstract.—The planktonic medusiform taxon Pararotadiscus guizhouensis (Zhao and Zhu, 1994) is one of the most abundant components of the Kaili Biota. Many specimens are in direct association with other taxa, including trilo- bites, brachiopods, hyolithids, echinoderms, and algae, as well as the trace fossil Gordia. Four types of interrelation- ships between P. guizhouensis and associated fossils are recognized: symbiosis, co-burial, attachment of benthic taxa on P. guizhouensis carcasses, and scavenging of P. guizhouensis carcasses. These associations of P. guizhouensis within the Kaili Biota are unique among occurrences of medusiform fossils in Burgess Shale-type biotas worldwide and provide important insights concerning ecological complexity in the Kaili Biota and in Cambrian marine commu- nities in general.


Introduction


Many important Cambrian Burgess Shale-type biotas have yielded the problematic medusiform fossils collectively referred to as eldonioids. Described taxa include Eldonia eumorpha Sun and Hou, 1987 and Rotadiscus grandis Sun and Hou, 1987 from the Chengjiang Biota of Yunnan Province, South China (Sun and Hou, 1987; Chen et al., 1996; Chen and Zhou, 1997; Hou et al., 1999, 2003; Zhu et al., 2002; Chen, 2004; Zhu, 2010); Eldonia ludwigi Walcott, 1911 from the Burgess Shale, Spence Shale, and Marjumbiotas of westernNorth America (Walcott, 1911; Conway Morris and Robison, 1986, 1988; Briggs et al., 1994; Caron and Jackson, 2008); Eldonia sp. from the Sinsk Biota of Siberia (Ivantsov et al., 2005); and Pararotadiscus guizhouensis (Zhao and Zhu, 1994) from the Kaili Biota of Guizhou Province, South China (Zhao and Zhu, 1994; Dzik et al., 1997; Zhu et al., 1999; Zhu et al., 2002; Cheng et al., 2009). All of the aforementioned eldonioids are characterized by a disc-shaped body with radial canals and concentric structures, a large alimentary canal, and well-developed tentacles. Specimens are typically preserved as carbonaceous compressions in mudstones, in some cases accom- panied by molds of the disc (Gaines et al., 2008).Most researchers have considered eldonioids to have had a planktonic mode of life (Sun and Hou, 1987; Zhao and Zhu, 1994; Zhu et al., 2002; Yang et al., 2007; Chen et al., 1995, 1996; Cheng et al., 2009), although others have interpreted them as benthic (Dzik et al., 1997) or nekto-benthic (Wang et al., 2004, 2009). Some eldonioids from Burgess Shale-type biotas are pre- served with other taxa. For example, the brachiopod Linguella


chengjiangensis Jin, Hou, and Wang, 1993 and the lobopods Microdictyon sinicumChen, Hou, and Lu, 1989 and Paucipodia inermis Chen, Zhou, and Ramsköld, 1995 are found on the discs of Eldonia eumorpha in the Chengjiang Biota (Chen and Zhou, 1997). In addition, the hyolithid Haplophrentis reesei Conway Morris and Robison, 1988 and the echinoderm Ctenocystis utahensis Robison and Sprinkle, 1969 are found on the discs of Eldonia ludwigi in the Spence Shale Biota (Conway Morris and Robison, 1986, 1988), and trace fossils are associated with an eldonioid in the Emu Bay Shale of South Australia (Schroeder et al., 2018). Here, we examine the paleoecological significance of taxa associated with specimens of Pararotadiscus guiz- houensis from the Cambrian Kaili Biota in Guizhou, South China (Zhao and Zhu, 1994; Dzik et al., 1997; Zhu et al., 2002; Cheng et al., 2009).


Research material and preservation


Pararotadiscus guizhouensis is very abundant in the Kaili Biota at the lowermost Cambrian Stage 5 (ca. 509 million year old) and is the only species of medusiform fossil known from the Kaili Formation (Zhao et al., 2011). This organism is found throughout the stratigraphic interval that bears the Kaili Biota, as well as in other horizons in the middle to upper part of the Kaili Formation at the Miaobanpo and the adjacent Wuliu- Zengjiayan (26°44.843’ N, 108°24.830’ E) sections at Balang village, Jianhe County, Guizhou Province, South China (Figs. 1, 2) (Zhao and Zhu, 1994; Zhu et al., 2002; Cheng et al., 2009; Zhao et al., 2011, 2012). The present study examined 628


972


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