Venus (Journal of the Malacological Society of Japan)
Online ISSN : 2189-7697
Print ISSN : 1348-2955
ISSN-L : 1348-2955
原著
先島諸島多良間島の古砂丘より産出した陸産貝類化石群集
藤江 明雄
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ジャーナル オープンアクセス

2002 年 60 巻 4 号 p. 295-302

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The ancient Nakasuji sand dune on Taramajima Island in the Sakishima Archipelago features two layers of intercalated eolian dust paleosol. The eolian dust layers have yielded terrestrial molluscan fossils in large numbers. There are in all 21 species of land mollusc, including six now extinct on the island. The fossils are predominantly minute fossils, but larger specimens are also preserved well without severe damage. This indicates that these assemblages are autochthonous. The species composition of the minute fossils differs from layer to layer. Gastrocopta (Sinalubinula) armigerella and Tornatellides boeningi are dominant in the lower paleosol layer and the underlying sand layer, while Georissa japonica, Carychium cymatoplax, Platyrhaphe hirasei nudus and Aphanoconia yaeyamaensis dominate the upper layer. Judging from the habitats of their Recent counterparts, it is inferred that the fossil assemblages in the lower layers were formed near the coast lines and that those in the upper layer were formed in and around coastal forests. This could be due to a fall in sea level associated with glacial eustasy in the last ice age.

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© 2002 日本貝類学会
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