Journal of Palaeogeography, 2018, 7(1): 1e13 (00134) Available online at www.sciencedirect.com ScienceDirect journal homepage: http://www.journals.elsevier.com/journal-of-palaeogeography/ Biopalaeogeography and palaeoecology Late Triassic sauropodomorph and Middle Jurassic theropod tracks from the Xichang Basin, Sichuan Province, southwestern China: First report of the ichnogenus Carmelopodus Li-Da Xing a,b,c,JinBad,*,MartinG.Lockleye, Hendrik Klein f, Sheng-Wu Yan d, Anthony Romilio g, Chun-Yong Chou b, W. S c o t t P e r s o n s I V h a State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China b School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China c State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu Province, China d Sichuan Institute of Geological Survey, Chengdu 610081, Sichuan Province, China e Dinosaur Trackers Research Group, University of Colorado Denver, PO Box 173364, Denver, CO 80217, USA f Saurierwelt Palaontologisches€ Museum, AlteRicht 7, D-92318 Neumarkt, Germany g School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia h Department of Biological Sciences, University of Alberta, 116 St & 85 Ave, Edmonton AB T6G 2R3, Alberta, Canada Abstract Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sau- ropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus (Late Triassic) and Liujianpus (Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger (Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation. Keywords Sauropodomorph, Theropod, Footprint, Ichnofossil, Upper Triassic Xujiahe Formation, Middle Jurassic Shaximiao Formation, Xichang Basin, Sichuan Province * Corresponding author. E-mail address: [email protected] (J. Ba). Peer review under responsibility of China University of Petroleum (Beijing). https://doi.org/10.1016/j.jop.2017.11.004 2095-3836/© 2017 China University of Petroleum (Beijing). Production and hosting by Elsevier B.V. on behalf of China University of Petroleum (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 2 L.-D. Xing et al. © 2017 China University of Petroleum (Beijing). Production and hosting by Elsevier B.V. on behalf of China University of Petroleum (Beijing). This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). Received 17 September 2017; accepted 18 October 2017; available online 23 November 2017 basin of the Xichang Basin, that include theropod, 1. Introduction sauropod, ornithopod, turtle and pterosaur tracks (Xing and Lockley, 2016). In contrast, track records Few Late Triassic tetrapod tracksites are known from the EmeieZhaojue sub-basin are sparse with only from China, with only one site (the Pengxianpus site; a single Early Cretaceous theropod tracksite that has Yang and Yang, 1987) known prior to 2013 (Matsukawa been previously reported (Xing et al., 2016d). et al., 2006). Since 2013, the Pengxianpus site was re- In August 2016, during the 1:50,000 regional examined and further three Late Triassic sites were geological survey of the Wumeng mountainous area, reported (Xing et al., 2013a, 2014a, 2014b) in addition the Sichuan Institute of Geological Survey discovered to two records from Middle Triassic strata that include dinosaur tracks at the base of the Middle Jurassic Chirotherium trackways (Lockley and Matsukawa, Shaximiao Formation in the EmeieZhaojue sub-basin. 2009; Lü et al., 2004; Xing et al., 2013b) and This site is located near Lemenhaluo Village (GPS: 0 00 0 00 possible nothosaur foraging tracks (Huang et al., 2012; 28 34 2.02 N, 103 0 28.16 E), Bingtu Township, Meigu Zhang et al., 2014). While tetrapod ichnofaunas from County in Yi Autonomous Prefecture of Liangshan. In Late TriassiceEarly Jurassic boundary sequences of September, a survey team found a second occurrence China have been described in several papers, foot- of dinosaur tracks approximately 12.2 km northeast of prints of sauropodomorphs were almost unknown, the Bingtu tracksite. This tracksite occurs at the top of except of a trackway of a possible bipedal archosaur the Upper Triassic Xujiahe Formation in the EmeieZ- from the Late Triassic of the Sichuan Basin that shows haojue sub-basin, and is located near Wadule Village, 0 00 some resemblance of the sauropodomorph ichnogenus Yiguojue Township, Meigu County (GPS: 28 39 50.21 N, 0 00 Eosauropus (Xing et al., 2014b). In contrast, the global 103 4 2.90 E; Fig. 1). Yan et al. (2017) briefly Triassic record of sauropodomorph tracks lists described the Bingtu tracksite, but did not provide numerous occurrences in both Late Triassic and Early morphologic details. Jurassic deposits (Li et al., 2012; Xing et al., 2014c, 2016a, 2016b, 2016c). Herein we describe sau- 2. Geological setting ropodomorph footprints from a new location, the Yiguojiao site of the TriassiceCretaceous Xichang Basin (Fig. 1), which represents another significant Late The Xichang Basin is positioned at the western edge Triassic tetrapod tracksite reported from China of the Upper Yangtze Platform and belongs to the (Fig. 1). This study is also an additional discovery from Tethyan structural domain. The HanyuaneGanluo the Bingtu tracksite in the Xichang Basin that belongs fracture zone divides the Xichang Basin into eastern to younger deposits of the Middle Jurassic Shaximiao and western sub-basins known as the EmeieZhaojue Formation (formerly “Xiashaximiao Formation”; the and the JiangzhoueMishi sub-basins, respectively prefixed “Xia” means “Lower”). From this locality, (Wang and Li, 1996). All tracks described in this paper tridactyl theropod tracks, attributable to Carmelopo- are from the EmeieZhaojue sub-basin. In this sub- dus, are documented. This is the first known occur- basin, Triassic and Jurassic strata are consistent with rence of this ichnogenus in China. those in the adjacent Sichuan Basin, and the outcrops The Xichang Basin is known for Cretaceous fossils, mainly belong to the Upper Triassic (Rhaetian) Xujiahe and prior to this report, Triassic or Jurassic dinosaur Formation with only a few Jurassic locations (Fig. 2; fossils were unknown, despite the extensive di- Peng et al., 2005; Qiao et al., 2012). The Jurassic mensions of this depression (roughly 16,000 km2) that strata consist of two Lower Jurassic formations includes Shimian, Xide, Zhaojue, and Meigu counties (Zhenzhuchong Formation and Ziliujing Formation), (Fig. 1; Fu and Qin, 2011; Liu et al., 2003), and borders two Middle Jurassic formations (Xintiangou Formation the southwestern region of the fossil-rich Sichuan and Shaximiao Formation), and two Upper Jurassic Basin. Since 2013, abundant Cretaceous dinosaur formations (Suining Formation and Penglaizhen For- tracks have been found in the JiangzhoueMishi sub- mation) (Gu et al., 1997; Li et al., 2011). Late Triassic sauropodomorph and Middle Jurassic theropod tracks 3 Fig. 1 Map showing the geographic position of footprint localities (footprint icon), the Yiguojiao tracksite (1) and the Bingtu tracksite (2) in Sichuan Province, southwestern China (modified from Xing and Lockley, 2016, their Fig. 1). Black thick solid line indicates outline of the Sichuan Basin; grey thick solid line indicates outline of the Xichang Basin; red line indicates the HanyuaneGanluo fracture zone. 2.1. Yiguojiao tracksite Lower Jurassic Ziliujing Formation conformably over- lies the Xujiahe Formation. The Xujiahe Formation is composed primarily of The Xujiahe Formation can be divided into two yellowish grey sandstone and mudstone interbedded lithologically distinct members (Wang and Li, 1996). with coal layers, forming rhythmic beds of alternating The lower member is characterized by a cyclothem thicknesses. The formation varies in total thickness composed of off-white, coarse-grained, feldspathic- from 450 m to 3000 m. Body fossils occur with bivalves, lithic quartz sandstone, fine-grained feldspar quartz brachiopods, ostracods, conchostracans, gastropods, sandstone, grey siltstone, black carbonaceous shale and plants (Xing et al., 2014b). The Xujiahe Formation with coal layers, and particularly large cross- in the EmeieZhaojue sub-basin begins with a bedding. The upper member is characterized by a 10e20 cm thick yellowish grey conglomeratic sand- sedimentary cycle comprising grey fineemedium- stone bed (mostly middle- to coarse-grained lithic grained feldspathic-lithic quartz sandstone, siltstone, quartz sandstone).