Measured profile of the Upper Railway-Dongpo Shiliu relationship group in Qujing area. Courtesy of Zhao Wenjin
Beijing, June 30 (Xinhua) -- Known as the "hometown of fish", Qujing, Yunnan Province, is currently the only paradise in the world where early fish inhabit and reproduce. Chinese scientists have made a series of important progress in the census and research of ancient fish fossils and related strata here, providing reliable paleoichthyological evidence for the in-depth study of the biological strata of the Silurian Period (about 420 million years ago) in China.
Measured profile of Liu Jiachongzhizhi liu in qujing area. Courtesy of Zhao Wenjin
The early vertebrate research team, composed of research experts and scholars from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (Institute of Paleovertebrates of the Chinese Academy of Sciences) and Qujing Normal College, recently published the latest achievement papers on the new discoveries of fish fossils in the Qujing Zhiliu Group and the new progress in stratigraphy research in the professional academic journals "Journal of Paleontology" and "Geological Frontier" respectively.
Strata of the Silurian Nexus Formation in Qujing Area: A. Guandi Group I; B. Guandi Group II. C. Guandi Group III. D. Guandi Group IV. E. Guandi Group III. Fossils of Coarse Worm Tubes in the Lower Part of Guandi Group III.; F. Fossils of shield-skinned fish in the middle of the third segment of the Guandi Formation. Courtesy of Zhao Wenjin
Zhao Wenjin, the corresponding author of the two papers and a researcher at the Institute of Paleovertebrates of the Chinese Academy of Sciences, said through an interview with reporters on the Internet on the 30th that the latest scientific research results are mainly based on the actual measurement data of two consecutive Guandi group profiles completed by the research team in recent years, and on the basis of the work of predecessors, according to lithological changes and paleontological fossil characteristics, the Guandi group containing rich Silurian fish fossils in Qujing area was redefined and divided, and its geological era was discussed in depth.
Fish micro-fossils in the Chongjiawan section of the Guandi Formation II of the Guandi Formation in Qujing Area: A-E. Spiny fish, of which A and B are unidentified species of thrus fish dorsal spiny fish 1, C is unspecified species of thrus spiny fish dorsal echinospora 2, D is unidentified species 3 of thrunch fish dorsal spiny fish, E is the jaw of the radial fish; F-G. Bony fish teeth; H-I. Bony fish spotted scales; J. No jaw incomplete bone pieces; Incomplete bone fragments of shield fish. Courtesy of Zhao Wenjin
The latest research progress made by the early vertebrate research team mainly includes four aspects:
First, the Qujing Guandi Formation is a set of shallow marine facies red layer sediments dominated by fine clastic rocks, and the Guandi Formation is divided into 4 sections according to the characteristics of lithological changes, from bottom to top, it is the Yuejiashan section of section I, the Chongjiawan section of Section II, the Cailian section of Section III and the eastern slope section of Section IV.
Second, the newly discovered fish fossils in the Chongjiawan section of the Guandi Group II. section are complete and rich, mainly including jawless, shield fish, spiny fish, scales, teeth and bone fragments of the bony fish, and mainly fish micro-fossilized stones such as spiny fish, durobony fish scales and teeth, which provide reliable paleoichthological evidence for the lower time limit of the Guandi Group, the era in the middle of the Yuejiashan section should be the early Silurian Rhodesian Gaost, and the lower part of the Yuejia Mountain section does not rule out the possibility of extending down to the Winlocks.
Third, through the global comparison of spiny fish micro-fossilization stones, the Myoko Formation of the overlying strata of the Guandi Formation can be classified into the lower Part of the Silurian Pridolidine, and the upper limit of the Age of the Guandi Formation should be the late Silurian Rhodesian.
Fourth, the geological era of the Qujing Guandi Formation is mainly limited to the Silurian Rhodesian, which is also the main distribution time limit of the Yangtze fish combination in the Xiaoxiang vertebrate fauna.
Comprehensive histogram of the Silurian lineage in Qujing area. Courtesy of Zhao Wenjin
Zhao Wenjin said that the Silurian in the Qujing area of Yunnan is well exposed, continuously developed, and rich in fossils, and has long been one of the ideal areas for studying Chinese Silurians. From the Silurian Rhodos 430 million years ago to the end of the Middle Devonian 380 million years ago, the vast majority of Paleozoic fish found in the world today can be found in Qujing. Not only that, Qujing also found many unique genera, including the earliest and most primitive representatives of their respective categories.
In the past 10 years, the early vertebrate research group of the Institute of Paleovertebrates of the Chinese Academy of Sciences has carried out a large number of field geological investigations and excavations and in-depth research of fish fossils in qujing area, in addition to discovering fish fossils that occupy a key node position in the evolution of early vertebrates and fish microsized stones of important stratigraphic significance, but also clarifying the fish composition, diversity and time-space distribution pattern of Xiaoxiang vertebrate fauna in Qujing area. It provides detailed first-hand field geological data and reliable paleofish for the discussion of the division and comparison of the formations of the Guandi Formation and their chronological attribution. (End)