Journal of Paleontology, 92(3), 2018, p. 478–487 Copyright © 2018, The Paleontological Society 0022-3360/18/0088-0906 doi: 10.1017/jpa.2017.93
A new millipede (Diplopoda, Helminthomorpha) from the Middle Triassic Luoping biota of Yunnan, Southwest China
Jinyuan Huang,1,2 Joseph T. Hannibal,3 Rodney M. Feldmann,4 Qiyue Zhang,1 Shixue Hu,1 Carrie E. Schweitzer,5 Michael J. Benton,6 Changyong Zhou,1 Wen Wen,1 and Tao Xie1
1Chengdu Center of China Geological Survey, Chengdu 610081, China ⟨
hjinyuan@cgs.cn⟩, ⟨
yxzqy@sina.com⟩, ⟨
hushixue@hotmail.com⟩,
⟨
zhcy79@163.com⟩, ⟨
wenwen2020240@163.com⟩, ⟨
xt1982cd@163.com⟩ 2Institute of Geological Survey, China University of Geosciences (Wuhan), Wuhan 430074, China 3Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH 44106-1767, U.S.A. ⟨
jhannibal@cmnh.org⟩ 4Department of Geology, Kent State University, Kent, Ohio 44242, U.S.A. ⟨
rfeldman@kent.edu⟩ 5Department of Geology, Kent State University at Stark, 6000 Frank Avenue NW, North Canton, Ohio 44720, U.S.A. ⟨
cschweit@kent.edu⟩ 6School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK ⟨
mike.benton@
bristol.ac.uk⟩
Abstract.—A new helminthomorph millipede, Sinosoma luopingense new genus new species, from the Triassic Luoping biota of China, has 39 body segments, metazonites with lateral swellings that bear a pair of posterolateral pits (?insertion pits for spine bases), and sternites that are unfused to the pleurotergites. This millipede shares a num- ber of characters with nematophoran diplopods, but lacks the prominent dorsal suture characteristic of that order. Other “millipede” material from the biota is more problematic. Millipedes are a rare part of the Luoping biota, which is composed mainly of marine and near-shore organisms. Occurrences of fossil millipedes are exceedingly rare in Triassic rocks worldwide, comprising specimens from Europe, Asia, and Africa, and consisting of juliform millipedes and millipedes that are either nematophorans or forms very similar to nematophorans.
Introduction
Millipedes are awidely distributed group of terrestrial arthropods (Shelley and Golovatch, 2011; Enghoff, 2015; Minelli, 2015). But, because of their terrestrial habitus, millipedes are rarely preserved as fossils. Fossil millipedes are mainly documented from the Paleozoic because they are relatively abundant in the extensive coal-forest deposits of the upper Carboniferous; they are also well documented in amber deposits, particularly those of the Cenozoic. Only rarely have they been described from the Mesozoic (Dzik, 1981; Jell, 1983; Duy-Jacquemin and Azar, 2004; Rasnitsyn and Golovatch, 2004; Shear et al., 2009; Shear and Edgecombe, 2010; Edgecombe, 2015; Liu et al., 2017). Mesozoic occurrences include two described genera from the Triassic (France and central Siberia), one genus fromthe Jurassic of Australia, and six genera from the Cretaceous (Mexico, Eur- ope, Lebanon,Mongolia, andMyanmar).Additional undescribed or poorly preserved millipedematerial is known fromthe Triassic of Africa and the Cretaceous of Europe. Asian Mesozoic occurrences are from the Cretaceous of
Mongolia (Dzik, 1975), Myanmar (Cockerell, 1917; Grimaldi et al., 2002; Rasnitsyn and Golovatch, 2004; Carlson, 2007; Liu et al., 2017), China (Huang, 2015, 2016), and the Triassic of Siberia (Dzik, 1981) and China (Hu et al., 2011). Fossil milli- pedes have been noted from three Mesozoic localities in China: Yanliao District (the famous fossil localities of Daohugou Biota) in Liaoning Province, Inner Mongolia, and Luoping County in Yunnan Province. Jurassic myriapods (including millipedes) have been noted from Daohugou (Huang, 2015,
2016), but they have been neither illustrated nor described, also a mid-Jurassic millipede is known from Inner Mongolia (D.Y. Huang, personal communication, 2017), but is yet to be illu- strated or described. Hu et al. (2011, p. 2279, fig. 5j) have noted the presence of millipedes in the Luoping fauna, illustrating one of those specimens. The purpose of this paper is to describe the specimen
illustrated by Hu et al. (2011, p. 2279, fig. 5), to briefly document another specimen with possible millipede affinity in the Luoping biota, and to provide brief comments on other Mesozoic millipedes.
The biota and its geological setting
The Luoping fossil Lagerstätte is located in Luoping County, Yunnan Province, southwest China (Fig. 1). This is in the southwestern part of the Yangtze Platform between the Nan- panjiang Basin and theYangtze Platform (Enos et al., 2006). The Luoping biota is part ofMember II of theGuanling Formation, of the Anisian stage (Middle Triassic), based upon conodont zona- tion (Huang et al., 2009; Zhang et al., 2009). The biota comprises a mixture of marine and terrestrial organisms (Hu et al., 2011) deposited in a marine environment. It includes typical marine reptiles, fishes, echinoderms (crinoids, sea urchins, sea cucum- bers, and sea stars), bivalves, gastropods, belemnoids, ammo- noids, brachiopods, conodonts, foraminiferans, and marine and nearshore arthropods. Among the thousands of fossils from the Luoping biota, arthropods, including lobsters, shrimp,
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