| Project/Area Number |
09640554
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Chiba University |
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Principal Investigator |
KOTAKE Nobuhiro Chiba University, Faculty of Sciences, Associate Professor, 理学部, 助教授 (00205402)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Trace Fossils / sedentary deposit feeders / mode of life and ethology / Mesozoic / Phytoplankton / 生活様式 / 定住生活の長期化 / 変遷史 / 中生代白亜紀 |
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| Research Abstract |
Based on the trace fossil analysis, the changes in mode of life and ethology on the deposit feeding animals which adopted sedentary life style in the past 500 million years were documented throughout this project. In addition, the relathionships between the change in mode of life and ethology on the deposit feeding animals and change in nutrient level have also discussed. The change in morphology of trace fossils occurring in the latest Paleozoic and the early to middle Mesozoic strata indicates that producing animals have not yet adopted long-term sedentary life style. This evidence strongly suggests that the change in mode of life of deposit feeders from short-term sedentary life style to long-term sedentary life style took place at the Cretaceous age. The inference is consistent with a hypothesis proposed by the author on the basis of the oversea examples.
Unfortunately, however, the information about the trace fossils occurring in the pelagic sediments deposited on the ocean floor, on where terrestrial particles did not reach, is still kacking. Therefore, detailed observation and morphological analysis of the trace fossils in the early to middle Mesozoic pelagic sediments are required to clarify the timing of the change in mode of life and ethology on the deposit feeding animals at the next stage.
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