Japan Geoscience Union Meeting 2016

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Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS13] Evolution of the Pelagic Realm

Mon. May 23, 2016 10:45 AM - 12:15 PM 203 (2F)

Convener:*Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University), Toshiyuki Kurihara(Graduate School of Science and Technology, Niigata University), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Tetsuji Onoue(Earth and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University), Katsunori Kimoto(Japan Agency for Marine-Earth Science and Technology), Tatsuo Nozaki(Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology), Hayato Ueda(Department of Geology, Niigata University), Kenta Kobayashi(Department of Geology, Faculty of Science, Niigata University), Takashi Hasegawa(Division of Global Environmental Science and Engineering, Graduate School of Natural Science and Technology, Kanazawa University), Chair:Tetsuji Onoue(Earth and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University), Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University)

10:45 AM - 11:00 AM

[MIS13-07] Phylogeny of Middle Jurassic Striatojaponocapsa and middle Cretaceous Turbocapsula, and potential of reliable radiolarian zonation

*Atsushi Matsuoka1, Xin Li2 (1.Department of Geology, Faculty of Science, Niigata University, 2.Graduate School of Science and Technology, Niigata University)

Keywords:radiolaria, phylogeny, zonation

The four-segmented Stichocapsa tegiminis Yao group gave rise to three-segmented Striatojaponocapsa plicarum (Yao). The evolutionary first appearance biohorizon defines the base of the Striatojaponocapsa plicarum Zone of Bajocian-early Bathonian age. In turn, Striatojaponocapsa plicarum (Yao) evolved into Striatojaponocapsa conexa (Matsuoka) through Striatojaponocapsa synconexa O’Dogerty, Gorican and Dumitrica. The evolutionary first appearance biohorizon of Striatojaponocapsa conexa defines the base of Striatojaponocapsa conexa Zone of late Bathonian-early Callovian age. This is a well-known evolutionary lineage of Middle Jurassic radiolarians and contributes to offer a reliable chronological framework. An evolutionary trend similar to the Striatojaponocapsa lineage is recognized in middle Cretaceous radiolarians belonging to the genus Turbocapsula. Four-segmented forms of Turbocapsula evolved into three-segmented Turbocapsula figitiva O’Dogerty by reducing segment number. Turbocapsula figitiva gave rise to Turbocapsula costata (Wu) by acquiring widely-spaced costae. This speciation is characterized by cladogenesis. The Turbocapsula lineage has a potential to produce a reliable radiolarian zonal scheme for the middle Cretaceous (Barremian-Aptian).