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The distribution pattern of early Telychian (turriculatus--crispus graptolite biozone) red beds in the Eastern Yangtze Platform of South China is reconstructed based on regional geologic data. The red beds are [...]

A large brachiopod fauna collected through the upper Wanyaoshu Formation (middle Hirnantian), West Yunnan, China displays, for the first time, a vertical transition within the Hirnantia fauna. The inner to mid‐shelf Fardenia–Hirnantia association segues into the deeper water Aegiromena–Anisopleurella association during the Metabolograptus persculptus marine transgression. This transition parallels the pattern apparent in onshore–offshore gradients within the Hirnantian, imitating Walther's Law for facies, instead predicting the seaward transitions between community types within a single transgressive sequence. In addition, large‐sized brachiopods such as Hirnantia and Eostropheodonta become rarer and small‐sized brachiopods, for example, Aegiromena and Anisopleurella more common. It is a rare opportunity to view transformations in community composition and structure within the Hirnantia fauna together with changes in both the size of individuals and populations (from large to small) during the transgression. [ABSTRACT FROM AUTHOR]

The brachiopods collected from the Kuanyinchiao Beds (Hirnantian, uppermost Ordovician) in Meitan and Zunyi counties, northern Guizhou, include 13 species and one undetermined taxon, dominated by Hirnantia sagittifera (M'Coy, 1851) (which accounts for over one-third of the specimens), together with common Eostropheodonta hirnantensis (M'Coy, 1851). They are assigned to the Hirnantia–Eostropheodonta Community, which probably inhabited a shallow-water, nearshore Benthic Assemblage (BA) 2 to upper BA 3 environment. Population analysis shows that the community was well adapted to this environment after the first phase of the end-Ordovician mass extinction. Representative specimens of all the species are illustrated, and a new species, Minutomena missa, is described herein. The variation in Hirnantia sagittifera was noted in many of previous studies but was not statistically evidenced. Here we have measured representative specimens of that famous species from the major paleoplates and terranes in the world, along with other species assigned to the genus from South China. Having used principal component analysis (PCA), significant variations in the species are documented statistically and revised, and three nominal species, one subspecies, and two morphotypes are now reassigned to Hirnantia sagittifera sensu stricto. UUID: http://zoobank.org/references/3f83fb1e-a6dd-4585-9f9f-9586dad28244 [ABSTRACT FROM AUTHOR]

Hirnantian costate craniides are rare in the world; many have only been defined using open taxonomic nomenclature and assigned to the genera Acanthocrania and Philhedra. New material from South China and Myanmar allows establishment of a new genus, Xenocrania, including its type species Palaeocyclus? haimei Reed from the Hirnantia fauna in northern Shan State, Myanmar. This genus is characterized by a unique ornamentation with a large degree of intraspecific variation in sympatric and allopatric populations. Three types of ornamentation (A, B and C) are recognized within the same population of this species, and even on the same individual. Based on this high degree of variation, we consider Xenocrania haimei and Acanthocrania yichangensis Zeng from the Hirnantia fauna of Yichang, western Hubei, South China to be conspecific. X. haimei was probably an opportunistic species, exhibiting considerable significant phenotypic pleiotropy (exemplified by a highly variable ornament) in response to severe ecological stress, particularly during the end Ordovician crisis, enabling the species to survive the extinction event. Geographically, Xenocrania gen. nov. occurs not only in the Hirnantia fauna of Myanmar (Sibumasu) and South China, but also in England (Avalonia), Poland (Baltica) and probably also Bohemia (Perunica). A further reassessment of many nominal or indeterminate taxa of Ordovician and Silurian craniides tentatively attributed to Philhedra, Acanthocrania and other related genera is needed. [ABSTRACT FROM AUTHOR]

A series of major geological and biological events which altered the evolutionary processes of whole biosphere occurred during the earth history. Establishing a high-resolution stratigraphic framework and timescale is essential to understand their tempo and causes. High-resolution biostratigraphy remains the most useful approach and forms the basis of dividing the chronostratigraphic system and making the inter-continental and regional correlation. China possesses nearly complete strata from Ediacaran to Quaternary covering wide palaeogeographic regions and containing abundant well-preserved fossils. Traditional biostratigraphy based on sytematic palaeontology of various fossil groups have played an important role in establishing the GSSPs and improving the International and Chinese Stratigraphic Charts. 11 out of 72 establised GSSPs are located in China. Recently, more high-precision geochronology, chemostratigraphy, cyclostrtatigraphy have been applied for stratigraphy and correlation and important advances have been made in some periods. This volume invited Chinese palaeontologists and stratigraphers to summarize the progresses of stratigraphy and timescale from Ediacaran to Quaternary and intercontinental and regional correlation during the last two decades. [ABSTRACT FROM AUTHOR]

Silurian is a period with the shortest duration in Phanerozoic except for the Neogene and Quaternary. It represents an important and unique interval when the biotic diversity recovered quickly after the end-Ordovician mass extinction, different paleoplates or terranes conjoined, big oceans disappeared or narrowed, climate and sea level changed frequently, global biotic provincialism became weaker, some primitive plants started to occupy the land. Silurian is also the first system of which all the chronostratigraphic stratotypes (i.e. the GSSPs) including four series and seven stages were established by the International Subcommission on Silurian Stratigraphy (ISSS). Nonetheless, during the post-GSSP studies conducted by ISSS in the middle 1980s, some Silurian GSSPs were found to have some congenital defects such as no index fossils available that hinder the high resolution subdivision and correlation on a regional or global scale. In this paper, based on the latest development of Silurian study in China, the progress in biostratigraphy, chronostratigraphy, event stratigraphy (such as facies differentiation, heterochrony of black shales, marine red beds, carbonate rocks and reefs), chemostratigraphy, and tectonic stratigraphy (e.g., widespread of the late Silurian rocks in South China and its tectonic implication) are systematically summarized. Some existing problems and the areas to be focused in future work are also discussed. It is suitable for chronostratigraphic study to concentrate not only on the boundary but also doing multidisciplinary analysis on the biotic, chemical, magnetic, environmental, and chronologic aspects, in order to enhance the reliability and the potential for regional and global correlation of a certain GSSP. Some important achievements are expected in these areas in the Silurian study in China: (1) ecostratigraphy and basin analysis of the Llandovery, and the correlation of integrative stratigraphy with a high resolution; (2) establishment of the Wenlock to Pridoli chronostratigraphic framework; (3) the chemo- and magnetic stratigraphy and the age of some key intervals and horizons; (4) further investigation on paleogeography and plate tectonics; and (5) origin and early evolution of the terrestrial ecosystem. Some new breakthroughs might occur in the restudy on some of those problematic GSSPs of some particular series and stages. [ABSTRACT FROM AUTHOR]

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Silurian brachiopods of Middle Llandovery ( Aeronian) ages are reviewed, and 215 genera are identified here, compared with 109 in the preceding Early Llandovery ( Rhuddanian), indicating a recovery-radiation interval after the end- Ordovician mass extinction. The chief regions in which they are found are the continents of South China, Avalonia- Baltica, Laurentia and Siberia, which were all at tropical latitudes with the exception of Avalonia. In addition, the very large superterrane of Gondwana, although with patchy brachiopod distribution, included temperate faunas, as well as subtropical faunas (in Iran and Afghanistan). Aeronian brachiopods greatly increased in diversity, with dominance of four major groups: orthides and strophomenides (which had flourished previously in the Rhuddanian), pentamerides and atrypides (which became dominant in the Aeronian), and many newly evolved taxa, and occupied deeper water and wider ecological niches (level bottom and reef) than those in the Rhuddanian. Each of the continents has some endemic genera, but there is a greater proportion of them in South China, where some groups (such as the pentamerides and atrypides) are more diverse and others, such as the orthides, are much less common than elsewhere. Affinity indices ( AI) show that two megaunits can be recognized: South China and Avalonia-Baltica-Laurentia ( ABL); Siberia seems to have been loosely connected with ABL and even more loosely to South China presumably because of its geographical separation in the Northern Hemisphere. The separation of South China from the other megaunits is further supported by cluster analysis. [ABSTRACT FROM AUTHOR]