The authors express their sincere thanks to Annika Sanfilippo of Scripps Institution of Oceanography (La Jolla, California, USA) and Toyosaburo Sakai of Utsunomiya University (Japan) for suggesting species identification of radiolarians. We also thank Christopher J. Hollis of the Institute of Geological and Nuclear Sciences (Lower Hutt, New Zealand) and Lorri Peters of Texas A&M University (ODP, College Station, Texas, USA) for reviewing the draft of this report. This work was financially supported by a Grant-in-Aid for Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists (number 1200254) for the first author. Part of this work was carried out at the Satellite Institution (Radiolaria) of Micropaleontological Reference Center in Utsunomiya University, Japan. This research used samples and/or data provided by the Ocean Drilling Program (ODP). ODP is sponsored by the U.S. National Science Foundation (NSF) and participating member countries under management of Joint Oceanographic Institutions (JOI), Inc.