This is a repository copy of Smithian platform-bearing gondolellid conodonts from Yiwagou Section, northwestern China and implications for their geographic distribution in the Early Triassic. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/148042/ Version: Accepted Version Article: Li, H, Jiang, H, Chen, Y et al. (6 more authors) (2019) Smithian platform-bearing gondolellid conodonts from Yiwagou Section, northwestern China and implications for their geographic distribution in the Early Triassic. Journal of Paleontology, 93 (3). pp. 496-511. ISSN 0022-3360 https://doi.org/10.1017/jpa.2018.93 © 2019, The Paleontological Society. This article has been published in a revised form in Journal of Paleontology [http://doi.org10.1017/jpa.2018.93]. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. 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[email protected] https://eprints.whiterose.ac.uk/ Journal of Paleontology For Review Only Smithian platform-bearing gondolellid conodonts from Yiwagou Section, northwestern China and implications for their geographic distribution in the Early Triassic Journal: Journal of Paleontology Manuscript ID JPA-RA-2018-0050.R3 Manuscript Type: Re ular Article Date Submitted by the Author: n/a Complete List of Authors: Lai, Xulon , China -ni.ersity of /eosciences, School of 0arth Sciences Li, 1an2iao, China -ni.ersity of /eosciences, School of 0arth Science Jian , 1aishui, China -ni.ersity of /eosciences, School of 0arth Science Chen, 3anlon , Northwest -ni.ersity, Department of /eolo y 6i nall, Paul, -ni.ersity of leeds, School of 0arth 7 0n.ironment 6u, 8ao9in, China -ni.ersity of /eosciences, School of 0arth Science :han , :aitian, China -ni.ersity of /eosciences, Colle e of Marine Science 7 Technolo y :han , Muhui, China -ni.ersity of /eosciences, School of 0arth Science Ouyan , :humin, China -ni.ersity of /eosciences, School of 0arth Science Ta2onomy: Conodonta 8road /eolo ic Time: Triassic < Mesozoic Detailed /eolo ic Time: Smithian (0arly Traissic), Smithian Sub9ect area /eo raphic Asia (eastern) Location: Cambridge University Press Page 1 of 56 Journal of Paleontology 1 1 Smithian platform-bearing gondolellid conodonts from Yiwagou 2 Section, northwestern China and implications for their geographic 3 distribution in the Early Triassic 4 5 Hanxiao Li1, Haishui Jiang1,2, Yanlong Chen3, Paul B. Wignall4, Baojin Wu1, Zaitian Zhang5, 1,2 1 1,2 6 Muhui Zhang , Zhumin ForOuyang andReview Xulong Lai * Only 7 8 1School of Earth Science, China University of Geosciences, Wuhan, Hubei 430074, China 9 <[email protected]> <[email protected]> <[email protected]> 10 <[email protected]> <[email protected]> 11 2State Key Laboratory of Geobiology and Environmental Geology, China University of 12 Geosciences, Wuhan, Hubei 430074, China 13 3Department of Geology, Northwest University, North Taibai Road 229, Xi’an 710069, China 14 <[email protected]> 15 4School of Earth & Environment, University of Leeds, Leeds, LS2 9JT, UK 16 <[email protected]> 17 5College of Marine Science & Technology, China University of Geosciences, Wuhan, Hubei 18 430074, China <[email protected]> 19 20 Abstract.—Abundant platformE.earing gondolellid conodonts including: Scythogondolella Cambridge University Press Journal of Paleontology Page 2 of 56 2 21 mosheri (:o8ur and Mostler), Sc. phryna Orchard and Zonne,eld, Scythogondolella cf. milleri 22 (MIller) ha,e been disco,ered fro the Yiwagou Section of Tewo, together with Novispathodus 23 waageni waageni (Sweet), Nv. w. eowaageni Zhao and Orchard. This is the first report of 24 S ithian platfor E.earing gondolellids fro the PaleoETethys region. In addition, 25 Eurygnathodus costatus Staesche, E. hamadai (:oike), Parafurnishius xuanhanensis Yang et al., 26 and the genera PachycladinaFor Staesche, Review Parachirognathus Only Clark, Hadrodontina Staesche ha,e 27 also been reco,ered fro Dienerian to S ithian strata at Yiwagou Section. Three conodont zones 28 are esta.lished, in ascending order: Eurygnathodus costatus-E. hamadai Asse .lage Zone, 29 Novispathodus waageni-Scythogondolella mosheri Asse .lage Zone, and the 30 PachycladinaEParachirognathus Asse .lage Zone. 31 The platfor E.earing gondolellids were globally distri.uted just after the endEPer ian mass 32 extinction, but the for erly a.undant Clarkina Ko8ur disappeared in the late Gries.achian. 33 Platfor E.earing gondolellids dra atically decreased to a mini u of di,ersity and extent in 34 the Dienerian before reco,ering in the S ithian. Scythogondolella Ko8ur, proba.ly a 35 ther ophilic and euryther ic genus, li,ed in all latitudes at this ti e whilst other genera did not 36 cope with S ithian high te peratures and so beco e restricted to the highElatitude regions. 37 Howe,er, the maxi u te perature in late S ithian likely caused the extinction of al ost all 38 platfor E.earing gonodlellids. Finally, the group returned to e5uatorial regions and achie,ed 39 global distri.ution again in the cooler conditions of the late Spathian. We conclude that 40 te perature (and to a lesser extent oxygen le,els) exerted a strong control on the geographical Cambridge University Press Page 3 of 56 Journal of Paleontology 3 41 distri.ution and e,olution of platfor E.earing gondolellids in the Early Triassic. 42 43 Introduction 44 45 The endEPer ian mass extinction was the most se,ere in geological history and saw the 46 disappearance of the majorityFor of marine Review organis s (e.g. Only Wignall, 2015). Ecosyste reco,ery 47 took se,eral million years and was hindered by the S ithianESpathian extinction around two 48 illion years after the main crisis. Early Triassic sea surface te peratures were especially high 49 and reached their zenith in the late S ithian (Sun et al., 2012L Ro ano et al., 2012). Black shales 50 and other anoxic facies were also widespread, especially in the late S ithian, although oxic 51 arine red beds (MRBs) .eca e co on in the early Spathian (Sun et al., 2015L Song et al., 52 2010). Thus, high seawater te peratures and anoxia in late S ithian may ha,e caused the 53 second order extinction e,ent at this ti e as seen a ongst conodonts (Orchard, 2000L Stanley, 54 2003), a onoids (Halla and Wignall, 1330L Brayard et al., 2003L Stanley, 2003) and bi,al,es 55 (Chen, 2004). The s all si8e of organis s (the Lilliput Effect), such as conodonts (Chen et al., 56 2013L Maekawa and Ko atsu, 2014) and gastropods (Piestch et al., 2014) ay also be 57 attri.uta.le to the high te peratures. 58 The ter ‘gondolellid’ deri,es fro the Fa ily -ondolellidae and is co posed of two 59 groups, seg iniplanate, platfor E.earing genera (eg. Neogondolella, Scythogondolella), and 60 seg inate, platfor Eless genera (eg. Neospathodus, Novispathodus). The fate of Cambridge University Press Journal of Paleontology Page 4 of 56 4 61 platfor E.earing gondolellid conodonts during the vicissitudes of the Early Triassic is unclear. 62 They were globally prosperous prior to the endEPer ian mass extinction and once again 63 successful in the Middle Triassic. Howe,er, in Early Triassic, conodonts in low latitude regions, 64 such as South China, were mostly do inated by bladeEshaped (or seg inate) instead of 65 platfor E.earing gondolellids. By co parison, in northern high latitude areas and the southern 66 argin of NeoETethys, theFor platfor ReviewE.earing gondolellids Only beco e more co on (e.g., Orchard 67 and Zonne,eld, 2003, Konstantino, et al., 2013L Bondarenko et al., 2015). Atte pts to elucidate 68 conodont biogeographic real s in the Early Triassic (e.g., Yang et al., 2001L Klets, 2008) are 69 currently ha pered by inco plete data fro so e regions. In this paper, we report newly 70 disco,ered and a.undant S ithian platfor E.earing gondolellid conodonts fro the Yiwagou 71 Section of Tewo County, -ansu Pro,ince, northwestern China that ena.les us to ad,ance 72 discussions of the e,olution of this i portant Triassic group. In addition a taxono ic description 73 is pro,ided for so e of the less well known conodonts (Parafurnishius xuanhanensis and se,eral 74 Scythogondolella species). 75 76 eological setting and stratigraphy 77 78 The Early Triassic Ninling Basin was a major seaway between the South China and Northern 79 China blocks that narrowed to the east and opened to PaleoETethys in the west (Lai et al., 1332, 80 1335, Yin and Peng, 1335, Feng et al., 1334). The studied Yiwagou Section was located in a Cambridge University Press Page 5 of 56 Journal of Paleontology 5 81 shallowEwater, car.onate platfor at the northern argin of South China Block and on the 82 southern side of the Basin (Fig. 1). There has been little research in the region because of its 83 inaccessi.ility and high altitude (.ut see Yin et al., 1388, 1332L Yin and Peng, 1335L Lai et al., 84 1332, 1334, 1335). The Yiwagou Section lies along a ra,ine near Zhagana village, Tewo County 85 (start point GPS 34.256N, 103.204E, Fig.