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Geobiology is a new discipline on the crossing interface between earth science and life science, and aims to understand the interaction and co-evolution between organisms and environments. On the basis of the latest international achievements, the new data presented in the Beijing geobiology forum sponsored by Chinese Academy of Sciences in 2013, and the papers in this special issue, here we present an overview of the progress and perspectives on three important frontiers, including geobiology of the critical periods in Earth history, geomicrobes and their responses and feedbacks to global environmental changes, and geobiology in extreme environments. Knowledge is greatly improved about the close relationship of some significant biotic events such as origin, radiation, extinction, and recovery of organisms with the deep Earth processes and the resultant environmental processes among oceans, land, and atmosphere in the critical periods, although the specific dynamics of the co-evolution between ancient life and paleoenvironments is still largely unknown. A variety of geomicrobial functional groups were found to respond sensitively to paleoenvironmental changes, which enable the establishment of proxies for paleoenvironmental reconstruction, and to play active roles on the Earth environmental changes via elemental biogeochemical cycles and mineral bio-transformations, but to be deciphered are the mechanisms of these functional groups that change paleoenvironmental conditions. Microbes of potential geobiology significance were found and isolated from some extreme environments with their biological properties partly understood, but little is known about their geobiological functions to change Earth environments. The biotic processes to alter or modify the environments are thus proposed to be the very issue geobiology aims to decipher in the future. Geobiology will greatly extend the temporal and spatial scope of biotic research on Earth and beyond. It has great potential of application in the domains of resource exploration and global change. To achieve these aims needs coordinative multidisciplinary studies concerning geomicrobiology and related themes, database and modeling of biogeochemical cycles, typical geological environments, and coupling of biological, physical, and chemical processes. [ABSTRACT FROM AUTHOR]

It is the first time to document the trilobite Mucronaspis (Songxites) wuningensis and the brachiopod Paromalomena-Aegiromenella Assemblage from the Xinkailing Bed (Hirnantian, uppermost Ordovician) in Taoyuan and Cili counties, northwestern Hunan Province. Synecological analysis shows that this is a deep water shelly fauna of South China during the Hirnantian. It lived on the upper Jiangnan Slope in northwestern Hunan, adjacent to the southeast margin of the Upper Yangtze Region, and belongs to the Hirnantia fauna with cool and deep water, and low diversity affinity, similar to its contemporary shelly faunas from the southern Shaanxi Slope adjacent to the north margin of the Upper Yangtze Region, the northern Chongqing depression (new name), and the Jiangxi-Anhui-Jiangsu gentle slope of the Lower Yangtze Region. Paleoecologically, it could be attributed to the BA 4-5 benthic regime (about 60-150 m deep, and deepest to 200 m), and was significantly different from the trilobite M. (S.) mucronata and the typical Hirnantia fauna while the latters may have habited in BA 2-3 benthic regimes (about 5-60 m deep). A new paleogeographic distribution pattern of the Hirnantian shallow and deep water shelly faunas of South China is herein proposed for the first time. Assuming that the depositional rate was constant in northwestern Hunan during the end Ordovician, the duration of the Xinkailing Bed might be only 12 thousand years according to the thickness of the Wufeng Formation and the absolute age values of those relevant graptolitic biozones. Such a short time interval may indicate that the global environmental change during the crisis was much shorter than previously thought, and its influence on the deep water regime was significantly shorter than that on the shallow water regime. [ABSTRACT FROM AUTHOR]