Diverse dinosaur ichnoassemblages from the Lower Cretaceous Dasheng Group in the Yishu fault zone, Shandong Province, China
Introduction
The famous Tanlu fault zone, which extends NNE–SSW for more than 3000 km, forms a conspicuous geological feature along the northeastern margin of the Asian continent (Zhang et al., 2003: Fig. 1A). A series of folded mountain systems and basins extends along the middle Tanlu fault zone, called the Yishu fault zone (along Zhucheng–Junan–Linshu–Tancheng) between the Shandong Province and the Jiangsu Province, in eastern China.
Extensive outcrops of Cretaceous strata, bearing abundant dinosaur tracks, were discovered in the Yishu fault zone. The localities that have so far been described include the Houzuoshan Dinosaur Park, Junan County, Shandong Province (Li et al., 2005a, Li et al., 2005b, Li et al., 2007, Lockley et al., 2007, Lockley et al., 2008), the Zhangzhuhewan tracksite, Zhucheng City, Shandong Province (Xing et al., 2010a), and the Nanguzhai tracksites, Donghai County, Jiangsu Province (Xing et al., 2010b). Additionally, several tracksites have been discovered in the Jiaolai Basin, eastern Shandong Province, such as the Huanglonggou tracksite from Zhucheng City (Li et al., 2011). This latter tracksite was excavated in 2010, and thousands of tracks were discovered.
The tracksites we describe here were also discovered in the Yishu fault zone. In 2005, a number of tracks were found by local quarry workers at Ji Mountain (in Chinese: Jishan) at the northern margin of the Maling Mountain (in Chinese: Malingshan) range, Linshu County, Shandong Province, approximately 24 km north of the Nanguzhai tracksites (Fig. 1A). At the end of 2010, the Linshu Land and Resources Bureau organised the protection and excavation of the Jishan tracksites. In 2011, the first author was invited by the Linshu Municipal Bureau to study dinosaur track material from the exposures of the area. In 2012, financed by the Qijiang International Dinosaur Tracks Symposium, a detailed study of the tracksite was carried out.
Section snippets
Institutional abbreviations
CLS = Costalomo site, Burgos Province, Spain; HDT = Huaxia Dinosaur Tracks Research and Development Center, Gansu, China; LCU = Las Cuestas tracksite, Cameros Basin, Spain; LRH–dz = Li Rihui–Dasheng, Qingdao Institute of Marine Geology, China Geological Survey, China; LS = Linshu County Bureau of Land and Resources, Shandong, China; ZPAL = Institute of Palaeobiology of the Polish Academy of Sciences, Warsaw, Poland.
Geological setting
The Yimu fault zone and the Jialai Basin Cretaceous strata are divided into the Lower Cretaceous Laiyang and Qingshan groups and the Upper Cretaceous Wangshi Group (Tan, 1923). The Lower Cretaceous Dasheng Group was mainly developed from the Yimu fault zone. The succession consists of a sequence of alluvial fan-fluvio-lacustrine rocks mixed with marls and limestones, which are fractured due to tectonic activity. It is divided into (in ascending order): Malangou, Tianjialou, Siqiancun, and
Methodology
At all sites tracks were examined by a majority of authors, photographed and, in many cases, outlined with chalk. At several sites with steeply inclined surfaces, ladders and mechanical devices (“cherry pickers”) were used to allow researchers to access the tracks without climbing. All trackways and track assemblages were traced on transparent plastic and acetate sheets.
Using a combination of photographs and tracings, maps of the more important surfaces and trackway segments were produced.
Description
One single trackway, composed of five consecutive pes tracks, catalogued individually as LSI-D1-R1, L1, R2, L2, R3 (Figs. 2 and 3; Table 1). The original trackway remains on Site I, where it is even possible to excavate more tracks at the end of the trackway. A replica was made by the Linshu Land and Resources Bureau, Shandong Province.
The pes tracks (19.5 cm length on average) are elongate with a rounded and quite deep (mean 3.8 cm, range 3–4.4 cm) depression (concave epirelief) comprising the
Vertebrate tracks from Shandong Area
Vertebrate tracks in Shandong Province are mainly present in the Lower Cretaceous Laiyang and Dasheng Groups. Abundant dinosaur body fossils were found in the Upper Cretaceous Wangshi Group (such as the hadrosaurid Shantungosaurus Hu et al., 2001, the ceratopsid Sinoceratops Xu et al., 2010a, Xu et al., 2010b, and the tyrannosaurid Zhuchengtyrannus Hone et al., 2011). Compared to the Upper Cretaceous Wangshi Group, vertebrate fossils are comparably rare in the Lower Cretaceous Laiyang and the
Conclusions
The new dinosaur ichnofauna from the Lower Cretaceous Dasheng Group of Shandong Province shows a remarkable diversity. It is a characteristic assemblage, comparable with others from coeval localities in the Yishu fault zone of eastern China.
Typical are trackways of large- and medium-sized sauropods that show some similarities with wide- and narrow-gauge ichnogenera such as Brontopodus and Parabrontopodus, and that possibly reflect different sauropod trackmaker groups, co-occurring with
Acknowledgements
The authors thank Yongqing Liu and Xuehong Kuang (Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China) and Rihui Li (Qingdao Institute of Marine Geology, China Geological Survey, Qingdao, China) for their critical comments and suggestions on this paper. Thanks to Qing He, Lei Mao, Jingjing Ao, Zhen Cui, Zhihua Li, Jian Hu for the assistance in the field and measuring of the tracks. Thanks to Mr. Yonggang Tang and Mrs. Rui Xu for assistance and logistical support during
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