Lufeng formation

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The Lufeng Formation ( Chinese 禄 丰 组 ; formerly Lower Lufeng Formation, 下 禄 丰 组 , of the Lufeng Group / Series) is a lithostratigraphic unit of continental sedimentary origin in the rank of a formation . It is of sub-Jurassic age and is common in Yunnan Province in southern China . It is named after Lufeng County in central Yunnan. The Lufeng Formation is of worldwide importance due to its content of fossil land vertebrates, especially dinosaurs and early mammals .

Stratigraphy and Lithologies

The formation is part of the sediment filling of the so-called Sichuan-Yunnan Basin, which comprises a sequence from the Upper Triassic to the Upper Cretaceous . The Lufeng Formation occurs today in the southern part (Yunnan Basin) of this former deposit area on the edge of some small-scale tectonic depressions (Lufeng Basin, Chuanjie Basin). In Lufeng Basin it reaches a thickness of over 730 meters, in Chuanjie Basin it is partially barely 275 meters thick. Internally, since 2000, it has been formally divided into the lower / older Shawan member and the upper / younger Zhangjia'ao member. For the "Lower Lufeng Formation" of traditional stratigraphy, a breakdown into the lower / older "dark / pale violet layers" is required. "Dark / dull purplish beds", and the upper / younger "deep / dark red layers". “Deep / dark red beds”, common (identical to the members of the new nomenclature).

The formation consists of an alternating layer of mostly reddish siltstones and claystones with inclusions of partly arcotic sandstones . The base of the formation is characterized by gravelly and conglomerate layers . Silt and clay stones were probably deposited at the bottom of lakes and in alluvial plains , sandstones, gravel and conglomerates in flowing water.

Based on certain of fossil shells and ostracods (ostracods) and on the composition of the vertebrate fossil fauna (see below) is considered an Early Jurassic Age of Lufeng lineup for granted. This is often further limited to the early Lower Jurassic (?  Hettangian and Sinemurian ). The Lufeng Formation is partly superimposed on the Upper Triassic Etouguang Formation (Kunyang Group) partly on Precambrian or Old Paleozoic basement and is overlaid by the Chuanjie Formation (formerly the lowest layers of the "Upper Lufeng Formation").

Fossil fauna

Skeleton reconstruction of the “prosauropod” Lufengosaurus magnus from the collection of the Natural History Museum Beijing

The Lufeng Formation is the most important vertebrate-bearing formation in the Chinese Lower Jurassic and one of the most important agricultural vertebrate-bearing formations in the Lower Jurassic worldwide. The first excavations took place in the 1930s after fossil bones had come to light during road construction.

The vertebrate fossil fauna is dominated by dinosaurs , especially by basal representatives of the Sauropodomorpha (" prosauropods " and early sauropods ), but also contains early representatives of the Crocodylomorpha and Sphenodontia as well as more modern Therapsids ("higher" Cynodontia including basal Mammaliaformes ). Before the discovery of Odontochelys in Guizhou Province, the Zhangjia'ao member of the Lufeng Formation contained the oldest, although not genus-classifiable, turtle fossils in China. The most common representative is the "prosauropod" Lufengosaurus . The early Mammaliaformes Morganucodon (including " Eozostrodon "), Sinoconodon and Hadrocodium are of particular tribal importance .

Furthermore, fossil footsteps and tracks have been known from the Lufeng formation since 2009 . The first finds were described as the new Ichnospecies Changpeipus pareschequier , belong to the three- toed (tridactylen) Grallator / Eubrontes -form circle and were probably produced by the coelophysoid theropods (" Dilophosaurus ", " Sinosaurus ", cf.  Megapnosaurus ) represented in the Lufeng fauna . In addition to further theropod traces, ornithic traces were found and assigned to the Ichno genus Shenmuichnus . The cause could have been the thyroid Tatisaurus and Bienosaurus represented in the Lufeng fauna . Step seals that can be assigned to the sauropodomorpha, which are so dominant in the body fossil fauna, are not known from the Lufeng Formation (as of 2016). Furthermore, numerous raised linear structures have been found on the bone surfaces of the skeleton of a “prosauropod” identified as cf. Yunnanosaurus , which were interpreted as diagenetically filled traces of carrion-consuming insects and described as a new trace genus Taotieichnus . In addition, there is a trace, probably created by invertebrates , cf.  Diplocraterion in the sediments .

Individual evidence

  1. ↑ Kui Li, Jian Liu, Chunyan Yang, Fang Hu: Dinosaur assemblages from the Middle Jurassic Shaximiao Formation and Chuanjie Formation in the Sichuan-Yunnan Basin, China. Volumes Jurassica. Vol. 9, No. 1, 2011, pp. 21–42, doi : 10.5604 / 17313708.1114169 (currently not available) Alternative link via URL , pp. 21 f.
  2. ↑ a b c Lida Xing, Eric M. Roberts, Jerald D. Harris, Murray K. Gingras, Hao Ran, Jianping Zhang, Xing Xu, Michael E. Burns, Zhiming Dong: Novel insect traces on a dinosaur skeleton from the Lower Jurassic Lufeng Formation of China. Palaeogeography, Palaeoclimatology, Palaeoecology. Vol. 388, 2013, pp. 58–68, doi: 10.1016 / j.palaeo.2013.07.028 (alternative full-text access : PDF of the accepted, unlayed manuscript on the IVPP pages; 1.85 MB)
  3. ↑ a b c d e Xiaoxi Fang, Qiqing Long, Liwu Lu, Zixiong Zhang, Shigang Pan, Yumin Wang, Xikang Li, Zhengwu Cheng: Lower, Middle, and Upper Jurassic subdivision in the Lufeng region, Yunnan Province. Pp. 208-214 in: Proceedings of the Third National Stratigraphical Congress of China. Geological Publishing House, Beijing 2000 ( PDF of the unofficial English translation on paleoglot.org; 80 kB)
  4. ↑ a b c d e Spencer G. Lucas: Chinese Fossil Vertebrates. Columbia University Press, New York 2001, ISBN 0-231-08482-X , p. 127 ff.
  5. ↑ Zhexi Luo, Xiao-Chun Wu: The small tetrapods of the Lower Lufeng Formation, Yunnan, China. Pp. 251-270 in Nicholas Frasier, Hans-Dieter Sues (ed.): In the Shadow of the Dinosaurs - Early Mesozoic Tetrapods. Cambridge University Press, Cambridge (UK) 1994, ISBN 0-521-45242-2
  6. ↑ Tomáš Daněk, Petr Skupien: Geotourism Aspects of the Lufeng Dinosaur National Geopark in Yunnan Province, China. GeoScience Engineering. Vol. 62, No. 1, 2016, pp. 51-57, doi: 10.1515 / gse-2016-0009
  7. ↑ Zhe-Xi Luo, Alfred W. Crompton, Ai-Lin Sun: A new mammaliaform from the Early Jurassic and evolution of mammalian characteristics. Science. Vol. 292, No. 5521, 2001, pp. 1535–1540, doi: 10.1126 / science.1058476 (alternative full text access: PDF from the main author's university homepage; 500 kB)
  8. ↑ Li-Da Xing, Jerald D. Harris, Toru Sekiya, Masato Fujita, Zhi-Ming Dong: Discovery of Dinosaur footprints from the Lower Jurassic Lufeng Formation of Yunnan Province, China, and new observations on Changeipus. Geological Bulletin of China. Vol. 28, No. 1, 2009, pp. 16–29 ( PDF on the Dixie State University website ; 13 MB)
  9. ↑ a b Lida Xing, Martin G. Lockley, Hendrik Klein, Jianping Zhang, W. Scott Persons IV: A new ornithischian-dominated an theropod footprint assemblage from the Lower Jurassic Lufeng Formation of Yunnan Province, China. Pp. 331-338 in: Robert M. Sullivan, Spencer G. Lucas (Eds.): Fossil Record 5. New Mexico Museum of Natural History and Science Bulletin. Vol. 74, 2016 ( PDF from the main author's private homepage; 2.6 MB)