Journal of Paleontology, 92(1), 2018, p. 14–25 Copyright © 2017, The Paleontological Society 0022-3360/18/0088-0906 doi: 10.1017/jpa.2017.39


New material of scalidophoran worms in Orsten-type preservation from the Cambrian Fortunian Stage of South China


Huaqiao Zhang,1 Andreas Maas,2 and Dieter Waloszek3


1State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China ⟨hqzhang@nigpas.ac.cn⟩ 2Galgenackerweg 25, 89134 Blaustein, Germany ⟨maas.blaustein@freenet.de⟩ 3University of Lund, Sölvegatan 12, SE-22362 Lund, Sweden ⟨dieter@waloszek-d.de⟩


Abstract.—Scalidophoran worms diversified in the Cambrian Fortunian, as indicated by recent reports from this stage, with two described species and two more unnamed forms exclusively from Orsten-type Lagerstätten yielding three-dimensionally phosphatized fossils. Here, we report new material of scalidophoran worms in Orsten-type preservation from the Cambrian Fortunian Xinli section in northern Sichuan Province, South China. At least five forms of scalidophoran worms were recovered from this location, including Eokinorhynchus rarus Zhang et al., 2015 and four unnamed taxa—Forms A, B, C, and D. Co-occurring disassociated spinose small shelly fossils might also be isolated cuticular elements of these early scalidophoran worms. The ontogeny of Eokinorhynchus rarus is revised. Forms A, C, and D are assigned to total-group Scalidophora to indicate their uncertain positions within Scalidophora, while Form B might be a close relative of Eokinorhynchus rarus. The current work highlights the significance of Orsten-type Lagerstätten in uncovering the morphology, ontogeny, and taxonomy of early Scalidophora and Cycloneuralia, made particularly available by the new finds in China.


Introduction


Cambrian Lagerstätten with exceptional preservation have opened unique windows into the origin and early evolution of metazoans. There are mainly two types of such Lagerstätten, which are especially influential: those of the typical Burgess Shale type (Conway Morris, 1989), including the Chengjiang or Maotianshan Shale type (Chen, 2004), and those of the Orsten type (Maas et al., 2006). In typical Burgess Shale type Lager- stätten, mainly macroscopic metazoans (of centimeter scale) can be completely preserved, but are preserved in a flat two-dimensional manner, in some cases as carbonaceous films (Gaines et al., 2005, 2008; Butterfield et al., 2007). Orsten-type Lagerstätten are a special mode of taphonomy (Müller and Walossek, 1985, 1991; Butterfield, 2003; Maas et al., 2006). In this case, only microscopic metazoans (at millimeter scale, generally no larger than 2 mm in size, down to 100 μm) have become three-dimensionally preserved by phosphate, better apatite, and an apparent replacement of the original surface (sometimes also secondary coating). Remarkable surface details are preserved so that the topology of body and surface structures can be directly observed in their original context and precisely reconstructed. Orsten-type preservation seems to affect mainly two taxa, both being specific chitin-cuticle-bearing animals, i.e., the cycloneuralians and panarthropods (Maas et al., 2006). Orsten-type preservation seems to preserve mainly components of the marine meiofauna, the small-scale animals living at or within the bottom layer of aquatic regimes. This is highly


14


significant since this fauna is lacking in almost all other Lager- stätten (Maas et al., 2006). Also of significance is that Orsten- type Lagerstätten occur at the coastline of more or less all microcontinents along the northern edge of the Cambrian supercontinent Gondwana and have a geological range from the early Cambrian to the Early Ordovician (Maas et al., 2006). Morphology-based phylogenetic analyses support mono-


phyly of Scalidophora (including Kinorhyncha, Loricifera, and Priapulida) and Nematoida (Nematoda and Nematomorpha). Together, these constitute the monophyletic Cycloneuralia (Ahlrichs, 1995; Nielsen, 2012). According to molecular estimates, the scalidophoran stem species should have lived in the Ediacaran Period and the group should have diversified in the Cambrian Fortunian (Rota-Stabelli et al., 2013). In fact, scalidophoran material was comparatively rare in the Cambrian Fortunian Stage. In a series of recent studies of Lagerstätten in China, the oldest known scalidophoran animals were recovered from the Cambrian Fortunian Zhangjiagou section and Xinli section, represented by Eopriapulites (Liu et al., 2014; Shao et al., 2016) and Eokinorhynchus (Zhang et al., 2015), respec- tively, and all specimens are preserved in Orsten-type preservation. Subsequently, continuous large-scale acetic-acid etching of rock samples recovered more scalidophoran material from the Xinli section, indicating potential high abundance and diversity. Here, we report more of the Orsten-type scalido- phoran material as part of a continuing study of Orsten-type scalidophorans from the Cambrian Fortunian Xinli section of South China.


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