(Table 3) Stratigraphic distribution of calcareous nannofossils from DSDP Hole 27-261@en

species abundance: A = abundant (>100 specimens), C = common (11-100 specimens), F = few (3-10 specimens), R = rare (1-2 specimens), ? = questionable, - = abundant, counting was performed using the light microscope over 200 fields of view物种丰度（species abundance）分级标准为：A为丰富（标本量＞100），C为常见（11~100个标本），F为少见（3~10个标本），R为稀有（1~2个标本），?表示存疑，-表示丰富；丰度计数通过光学显微镜（light microscope）在200个以上视野中完成。