四川西昌盆地白垩纪恐龙足迹群的新发现
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摘要
四川西昌盆地白垩系小坝组尚未发现骨骼化石记录,其白垩系恐龙动物群的信息全赖于足迹化石。2017年,在喜德县洛甘发现小坝组迄今最大型的恐龙足迹群。该足迹点保存了大量的兽脚类足迹。足迹保存条件较差,但具备了基本的形态学特征。总体来看,兽脚类足迹具有尺寸较小(8~13cm),中等中趾前凹(0.5~0.6)和第Ⅱ趾和第Ⅳ趾间较宽趾间角(70°~100°)的特征;少量足迹保存了跖骨垫。初步分析认为,洛甘兽脚类足迹与四川盆地夹关组的兽脚类足迹Eubrontes和Grallator形态类型相似,为两地在白垩纪中期具有类似的恐龙动物群的观点提供了新的证据。该发现对于西昌盆地的古气候、古地理和地层对比都具有重要的意义,足迹详细分类还有待进一步研究。
The dinosaur fossils haven't been recorded in Cretaceous Xiaoba Formation in Xichang basin, Sichuan Province. Hence,the dinosaur footprints provide crucial information for improving the understanding of the Cretaceous dinosaur assemblages. In April2007, the authors discovered a new dinosaur footprint assemblage in Xiaoba Formation at Luogan Township, Xide County. The Luogan tracksite is poorly preserved, but it contains abundant theropod tracks with basic morphological features. In general, the small the-ropod tracks(8~13 cm) are characterized by moderate mesaxony(0.5~0.6) and wide divarication angles between digits II and IV(70°~100°), few of which developed metatarsal pads. The authors tentatively hold that the Luogan theropod assemblages are probably similar to Eubrontes and Grallator of Jiaguan Formation in Sichuan basin, which provides new evidence that these two areas had similar dinosaur faunae in Middle Cretaceous. This discovery is of great significance for paleoclimate, paleogeography and stratigraphic contrast in Xichang basin. Detailed classification of footprints needs further study.
The dinosaur fossils haven't been recorded in Cretaceous Xiaoba Formation in Xichang basin, Sichuan Province. Hence,the dinosaur footprints provide crucial information for improving the understanding of the Cretaceous dinosaur assemblages. In April2007, the authors discovered a new dinosaur footprint assemblage in Xiaoba Formation at Luogan Township, Xide County. The Luogan tracksite is poorly preserved, but it contains abundant theropod tracks with basic morphological features. In general, the small the-ropod tracks(8~13 cm) are characterized by moderate mesaxony(0.5~0.6) and wide divarication angles between digits II and IV(70°~100°), few of which developed metatarsal pads. The authors tentatively hold that the Luogan theropod assemblages are probably similar to Eubrontes and Grallator of Jiaguan Formation in Sichuan basin, which provides new evidence that these two areas had similar dinosaur faunae in Middle Cretaceous. This discovery is of great significance for paleoclimate, paleogeography and stratigraphic contrast in Xichang basin. Detailed classification of footprints needs further study.
引文
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[12]Xing L D,Lockley M G.First Report of Small Ornithopodichnus Trackways from the Lower Cretaceous of Sichuan,China[J].Ichnos,2014,21(4):213-222.
[13]Xing L D,Lockley M G,Zhang J P,et al.Diverse sauropod-,theropod-,and ornithopod-track assemblages and a new ichnotaxon Siamopodus xui ichnosp.nov.from the Feitianshan Formation,Lower Cretaceous of Sichuan Province,southwest China[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2014,414:79-97.
[14]Xing L D,Lockley M G,Yang G,et al.A diversified vertebrate ichnite fauna from the Feitianshan Formation(Lower Cretaceous)of southwestern Sichuan,China[J].Cretaceous Research,2016,57:79-89.
[15]Wilson C J L,Fowler A.Denudational response to surface uplift in east Tibet:Evidence from apatite fission track thermochronology[J].Geological Socety of America Bulletin,2011,123(9/10):1966-1987.
[16]Deng B,Liu S,Jiang L,et al.Tectonic uplift of the Xichang Basin(SE Tibetan Plateau)revealed by structural geology and thermochronology data[J].Basin Research,2017,30(1):1-22.
[17]辜学达,刘啸虎.四川省岩石地层[M].武汉:中国地质大学出版社,1997:1-417.
[18]Lockley M G.New perspectives on morphological variation in tridactyl footprints:clues to widespread convergence in developmental dynamics[J].Geological Quarterly,2009,53:415-432.
[19]Xing L D,Lockley M G,Klein H,et al.The non-avian theropod track Jialingpus from the Cretaceous of the Ordos Basin,China,with a revision of the type material:implications for ichnotaxonomy and trackmaker morphology[J].Palaeoworld,2014,23:187-199.
[20]Xing L D,Lockley M G,Zhang J P,et al.The longest theropod trackway from East Asia,and a diverse sauropod-,theropod-,and ornithopod-track assemblage from the Lower Cretaceous Jiaguan Formation,southwest China[J].Cretaceous Research,2015,56:345-362.
[2]四川盆地陆相中生代地层古生物编写组.四川盆地陆相中生代地层古生物[M].成都:四川人民出版社,1984:1-742.
[3]张云湘,骆耀南,杨崇喜,等.攀西裂谷[M].北京:地质出版社,1988:1-325.
[4]Tamai M,Liu Y,Lu L Z,et al.Palaeomagnetic evidence for southward displacement of the Chuan Dian fragment of the Yangtze Block[J].Geophysical Journal International,2004,158(1):297-309.
[5]邢立达,马丁·洛克利,张建平.中国西南早白垩世恐龙及其他四足类足迹[M].宁波:宁波出版社,2017:1-410.
[6]曹俊,邢立达,杨更,等.基于恐龙足迹重建攀西地区白垩纪恐龙动物群[J].地质通报,2016,35(12):1961-1966.
[7]刘建,李奎,杨春燕,等.四川昭觉恐龙足迹化石的研究及其意义[C]//中国古生物学会第十次全国会员代表大会暨第25届学术年会论文摘要集,2009,10:195-196.
[8]Liu J,Li K,Yang C Y,et al.Preliminary study on fossils of dinosaur footprints and its significance from Zhaojue area of Xichang County in Sichuan Province[C]//Marine and non-marine Jurassic-short papers for the 8th International Congress on the Jurassic System,2010:230-231.
[9]Xing L D,Lockley M G,Marty D,et al.Re-description of the partially collapsed Early Cretaceous Zhaojue dinosaur tracksite(Sichuan Province,China)by using previously registered video coverage[J].Cretaceous Research,2015,52:138-152.
[10]Xing L D,Lockley M G,Yang G,et al.Tracking a legend:An Early Cretaceous sauropod trackway from Zhaojue County,Sichuan Province,southwestern China[J].Ichnos,2015,22(1):22-28.
[11]Xing L D,Lockley M G,Yang G,et al.Unusual deinonychosaurian track morphology(Velociraptorichnus zhangi n.ichno sp.)from the Lower Cretaceous Xiaoba Formation,Sichuan Province,China[J].Palaeoworld,2015,24(3):283-292.
[12]Xing L D,Lockley M G.First Report of Small Ornithopodichnus Trackways from the Lower Cretaceous of Sichuan,China[J].Ichnos,2014,21(4):213-222.
[13]Xing L D,Lockley M G,Zhang J P,et al.Diverse sauropod-,theropod-,and ornithopod-track assemblages and a new ichnotaxon Siamopodus xui ichnosp.nov.from the Feitianshan Formation,Lower Cretaceous of Sichuan Province,southwest China[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2014,414:79-97.
[14]Xing L D,Lockley M G,Yang G,et al.A diversified vertebrate ichnite fauna from the Feitianshan Formation(Lower Cretaceous)of southwestern Sichuan,China[J].Cretaceous Research,2016,57:79-89.
[15]Wilson C J L,Fowler A.Denudational response to surface uplift in east Tibet:Evidence from apatite fission track thermochronology[J].Geological Socety of America Bulletin,2011,123(9/10):1966-1987.
[16]Deng B,Liu S,Jiang L,et al.Tectonic uplift of the Xichang Basin(SE Tibetan Plateau)revealed by structural geology and thermochronology data[J].Basin Research,2017,30(1):1-22.
[17]辜学达,刘啸虎.四川省岩石地层[M].武汉:中国地质大学出版社,1997:1-417.
[18]Lockley M G.New perspectives on morphological variation in tridactyl footprints:clues to widespread convergence in developmental dynamics[J].Geological Quarterly,2009,53:415-432.
[19]Xing L D,Lockley M G,Klein H,et al.The non-avian theropod track Jialingpus from the Cretaceous of the Ordos Basin,China,with a revision of the type material:implications for ichnotaxonomy and trackmaker morphology[J].Palaeoworld,2014,23:187-199.
[20]Xing L D,Lockley M G,Zhang J P,et al.The longest theropod trackway from East Asia,and a diverse sauropod-,theropod-,and ornithopod-track assemblage from the Lower Cretaceous Jiaguan Formation,southwest China[J].Cretaceous Research,2015,56:345-362.