HIRNANTIAN (LATEST ORDOVICIAN) GRAPTOLITES FROM THE UPPER YANGTZE REGION, CHINA

Abstract:  The Upper Yangtze region yields a Hirnantian (latest Ordovician) graptolite fauna that includes 41 species assigned to 13 genera. This fauna is particularly important for understanding the Late Ordovician mass extinction event because it is the most diverse known from this interval. In addition, it records the survival, well into the Hirnantian, of many taxa of the Dicranograptidae‐Diplograptidae‐Orthograptidae (DDO) fauna, which was previously regarded as having gone extinct at the beginning of the Hirnantian. Taxa exhibiting six different astogenetic patterns, including taxa with reclined stipes, scandent, biserial, full‐periderm and ‘archiretiolitid’ rhabdosome forms occur in the lower Normalograptus extraordinarius‐N. ojsuensis Biozone. In contrast, in the upper N. persculptus Biozone only four genera remain, all but one of which are Normalograptidae: scandent and biserial taxa with Pattern H astogeny. Normalograptids are the dominant form of the succeeding, lower Rhuddanian, faunas. The Yangtze faunas also document the early expansion of normalograptids coeval with the decline of the DDO fauna. Many previously identified species considered endemic to China have been synonymized; 24 of the 41 species recorded here have been recognized elsewhere. No new taxa are described.

[1]  D. Harper,et al.  A relict Ordovician brachiopod fauna from the Parakidograptus acuminatus Biozone (lower Silurian) of the English Lake District , 2002 .

[2]  D. Mikulic,et al.  GRAPTOLITES FROM NEAR THE ORDOVICIAN-SILURIAN BOUNDARY IN ILLINOIS AND IOWA , 2002, Journal of Paleontology.

[3]  M. Melchin,et al.  LOWERMOST SILURIAN GRAPTOLITES FROM THE KURAMA RANGE, EASTERN UZBEKISTAN , 2000 .

[4]  C. Mitchell,et al.  Late Ordovician to earliest Silurian graptolite and brachiopod biozonation from the Yangtze region, South China, with a global correlation , 2000, Geological Magazine.

[5]  M. Melchin,et al.  DEVELOPMENT, TAXONOMY, AND PHYLOGENETIC RELATIONSHIPS OF SPECIES OF PARACLIMACOGRAPTUS (GRAPTOLOIDEA) FROM THE CANADIAN ARCTIC AND THE SOUTHERN URALS OF RUSSIA , 2000, Journal of Paleontology.

[6]  J. Cooper,et al.  Late Ordovician mass extinction: A new perspective from stratigraphic sections in central Nevada , 1999 .

[7]  C. Underwood,et al.  High palaeolatitude (Hodh, Mauritania) recovery of graptolite faunas after the Hirnantian (end Ordovician) extinction event , 1998 .

[8]  C. Mitchell,et al.  Anticostia, a distinctive new Late Ordovician "glyptograptid" (Diplograptacea, Graptoloidea) based on three-dimensionally preserved specimens from Anticosti Island, Quebec , 1997 .

[9]  M. Melchin,et al.  The Ordovician–Silurian boundary on Cornwallis and Truro islands, Arctic Canada: preliminary data , 1991 .

[10]  D. Bates.  Retiolite nomenclature and relationships , 1990, Journal of the Geological Society.

[11]  J. Riva.  The graptolite Amplexograptus praetypicalis n. sp. and the origin of the typicalis group , 1987 .

[12]  M. Howe.  Measurement of thecal spacing in graptolites , 1983, Geological Magazine.

[13]  D. Batten,et al.  The Llandovery Graptolites of the English Lake District , 1974, Monographs of the Palaeontographical Society.

[14]  I. Strachan.  A Synoptic Supplement to “A Monograph of British Graptolites by Miss G. L. Elles and Miss E. M. R. Wood” , 1971, Monographs of the Palaeontographical Society.

[15]  R. Rickards.  The Llandovery (Silurian) Graptolites of the Howgill Fells, Northern England , 1969, Monographs of the Palaeontographical Society.

[16]  R. Barrass.  Graptolites from Anticosti Island , 1954, Quarterly Journal of the Geological Society of London.

[17]  A. Eisenack.  Neue Graptolithen aus Geschieben baltischen Silurs , 1935 .

[18]  I. Cox.  On Climacograptus inuiti sp. nov. and its Development , 1933, Geological Magazine.

[19]  K. A. Davies.  Notes on the Graptolite Faunas of the Upper Ordovician and Lower Silurian , 1929, Geological Magazine.

[20]  R. Gurley.  North American Graptolites: New Species and Vertical Range , 1896, The Journal of Geology.

[21]  J. Hopkinson.  V.—On Dicellograpsus, a New Genus of Graptolites , 1871, Geological Magazine.

[22]  W. Carruthers.  VI.—Note on the Systematic Position of Graptolites, and on their supposed Ovarian Vesicles , 1867, Geological Magazine.

[23]  C. Mitchell,et al.  Proposal of a GSSP candidate section in the Yangtze platform region, S. China, for a new Hirnantian boundary stratotype , 1999 .

[24]  Li Jijin.  Lower Silurian graptolites from the Yangtze Gorge district , 1995 .

[25]  A.V. Kovalyov.  An O , 1995, Proceedings of Tenth International Symposium on Intelligent Control.

[26]  J. Zalasiewicz,et al.  Uppermost Ordovician to Lower Silurian graptolite biostratigraphy of the Wye valley, central Wales , 1994 .

[27]  P. Štorch,et al.  Lower Silurian graptolites from southwestern Sardinia , 1993 .

[28]  R. Cooper,et al.  The Ordovician graptolite sequence of Australasia , 1992 .

[29]  P. Brenchley,et al.  Ordovician , 1992, Geological Society, London, Memoirs.

[30]  C. Mitchell,et al.  Late Ordovician Extinction in the Graptoloidea , 1991 .

[31]  A. Vandenberg.  The ancestry of Climacograptus spiniferus Ruedemann , 1990 .

[32]  K. B. Ketner,et al.  Ordovician graptolites from the northern Sierra de Cobachi, Sonora, Mexico , 1989, Transactions of the Royal Society of Edinburgh: Earth Sciences.

[33]  Yue Jianhua,et al.  LUNGMACHI FORMATION GRAPTOLITES FROM SANLANGPU OF XIXIANG, SOUTHERN SHAANXI , 1988 .

[34]  R. Sobolevskaya,et al.  The Ordovician-Silurian boundary beds of the north-east USSR , 1988 .

[35]  M. Melchin.  Upper Ordovician graptolites from the Cape Phillips Formation, Canadian Arctic Islands , 1987, Bulletin of the Geological Society of Denmark.

[36]  Jianhua Yu,et al.  The Ordovician graptolite-bearing strata of Xiushui drainage basin, Jiangxi, southern China and their correlation , 1986, Geological Society, London, Special Publications.

[37]  S. Finney.  Heterochrony, punctuated equilibrium, and graptolite zonal boundaries , 1986, Geological Society, London, Special Publications.

[38]  W. Berry.  Stratigraphic significance of Glyptograptus persculptus group graptolites in central Nevada, U.S.A. , 1986, Geological Society, London, Special Publications.

[39]  P. Legrand.  The lower Silurian graptolites of Oued In Djerane: a study of populations at the Ordovician-Silurian boundary , 1986, Geological Society, London, Special Publications.

[40]  R. B. Rickards,et al.  The Ordovician-Silurian boundary at Darraweit Guim, central Victoria , 1984 .

[41]  Rong Jiayu.  Distribution of the Hirnantia fauna and its meaning , 1984 .

[42]  Chen Xu,et al.  On the material of Glyptograptus persculptus (Salter) from the Yangtze Gorges, China , 1984 .

[43]  Chen Xu,et al.  Correlation of Ashgill graptolite faunas of central China and arctic Canada，with a description of Diceratograptus cf. mirus Mu from Canada , 1984 .

[44]  Ni Yunan,et al.  Uppermost Ordovician and lowermost Silurian graptolites from the Xainza area of Xizang (Tibet) with discussion on the Ordovician-Silurian boundary , 1983 .

[45]  S. Williams.  Upper Ordovician graptolites from the top Lower Hartfell Shale Formation (D. clingani and P. linearis zones) near Moffat, southern Scotland , 1982, Transactions of the Royal Society of Edinburgh: Earth Sciences.

[46]  R. Sobolevskaya,et al.  KEW EVIDENCE ON GRAPTOLITE SUCCESSION ACROSS THE ORDOVICIAN-SILURIAN BOUNDARY IN THE ASIAN PART OF THE USSR , 1979 .

[47]  C. Carter,et al.  Ordovician and Silurian graptolite succession in the Trail Creek area, central Idaho; a graptolite zone reference section , 1977 .

[48]  C. Carter,et al.  Early Silurian graptolites from southeastern Alaska and their correlation with graptolitic sequences in North America and the Arctic , 1970 .

[49]  W. Berry,et al.  Ordovician Graptolites of the Basin Ranges in California, Nevada, Utah, and Idaho , 1963 .

[50]  O. Bulman,et al.  Graptolithina with sections on enteropneusta and pterobranchia , 1955 .

[51]  R. Ruedemann.  Graptolites of North America , 1947 .

[52]  S. C. Hsü.  The graptolites of the lower Yangtze valley = 長江下游之筆石化石 , 1934 .