Mesorbitolina (Cretaceous larger foraminifera) from the Yezo Group in Hokkaido, Japan and its stratigraphic and paleobiogeographic significance

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概要

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• In this paper, we describe an Aptian (Early Cretaceous) larger foraminiferal species Orbitolina (Mesorbitolina) parva from the limestone olistoliths in the lower part of the Yezo Group in the Yubari-Ashibetsu area, central Hokkaido and from limestone pebbles in the lowermost part of the Yezo Group in the Nakagawa area, northern Hokkaido. This is the first report of this species from the circum-North Pacific regions. Based on its occurrences, the shallow-marine carbonates, re-deposited in the lower part of the Yezo Group, are precisely assigned in age to the Late Aptian. Comparison of the lower part of the Yezo Group in central and northern Hokkaido indicates differences of the Aptian-Albian depositional history between the two areas. This study reveals that after Late Aptian, Mesogean key taxa (typical Cretaceous Tethyan biota) demised in the Northwest Pacific.(Communicated by Tatsuro MATSUMOTO, M.J.A.)

• 日本学士院の論文

著者

• SANO SHIN-ICHI

  Fukui Prefectural Dinosaur Museum

• Iba Yasuhiro

  Department Of Geology And Paleontology National Museum Of Nature And Science

• IBA Yasuhiro

  Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo

関連論文

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• Early Albian Mytiloides (Inoceramidae, Bivalvia) from the Northwest Pacific : a pioneering species for Late Cretaceous inoceramid diversification
• A Tethyan bivalve, Neithea (Cretaceous pectinid) from northern California, and its biogeographic implications
• Mesorbitolina (Cretaceous larger foraminifera) from the Yezo Group in Hokkaido, Japan and its stratigraphic and paleobiogeographic significance

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