1994 Fiscal Year Final Research Report Summary
Studies on a process of formation of an island-form mammalian faunas in the Nansei Islands
| Project/Area Number |
05640518
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Kagoshima University |
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Principal Investigator |
OTSUKA Hiroyuki Kagoshima Univ. Professor, 理学部, 教授 (50041223)
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| Co-Investigator(Kenkyū-buntansha) |
OKI Kimihiko Kagoshima Univ. Associate Prof., 理学部, 助教授 (90041235)
NISHINAKAGAWA Hayao Kagoshima Univ. Professor, 農学部, 教授 (70041639)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Nansei Islands / mammalian fauna / Pleistocene / geographic isolation / fossil deer / relic species / fissure deposits / 裂罅堆積物 |
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| Research Abstract |
1) To clarify the geologic age and a history of the Tokara Channel, the Pleistocence Masuda Formation in the Tanegashima Island was studied in detail basis on the stratigraphy, magnetostratigraphy and the paleontology. Taking account the fission-track ages, this formation can be correlated with the Early Pleistocene magnetozone ranging from the later half of the Matuyama Reversed Epoch to the early half of the Brunhes Normal Epoch.
2) A fossil frog from the Masuda Formation was identified with the species now living in the Amami Islands, south of Tokara Channel. From this discovery, it may be inferred that Osumi and the AmamiIslands might be connected at the Early Pleistocene.
3) A molar of fossil elephant discovered at 1939 from the Miyako Island was re-examined in detail and was identified with an archetypal mammoth-Mammuthus armeniacus shigensis which is commonly occurred from the Early Pleistocene deposits of the Japanese Islands and Taiwan. The result imply that the land connection between the Miyako Island and the continental area has taken placed at the late Early Pleistocene.
4) Based on the morphological and statistical studies on fossil deers from the Nansei Islands, the writer tried to scrutinize the evolutionary trend of the body proportion of fossil deer in the islands and to establish the probable order of migration of terrestrial vertebrates to the Okinawa-jima.
5) Based on the analysis on the fossil-and living mammalian faunas and its geologic ages, following three stages of the land connection of the Nansei Island to the continent are proposed, namely, Stage I of the Early Pleis tocene, Stage II of the late Middle Pleistocene and Stage III of the Latest Pleistoce.
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