(Table DR1) Biofacies, percentages of important benthic foraminifera and isotope data at ODP Site 758

The Indian monsoon system, as recorded by ocean-floor biota (benthic foraminifera) at Ocean Drilling Program Site 758 in the eastern equatorial Indian Ocean, has varied dramatically over the past 5.5 m.y., long after the onset of the monsoons at 10-8 Ma. Benthic foraminifera that thrive with high productivity year-round were common before the formation of Northern Hemisphere continental ice sheets ca. 3.1-2.5 Ma, indicating that the summer (southwest) monsoon had high intensity and long seasonal duration. Ca. 2.8 Ma benthic faunas became dominated by taxa that flourish with a seasonally strongly fluctuating food supply, indicating that the northeast (winter) monsoon, during which primary productivity is relatively low, increased in duration and strength to form a system similar to that of today. The change occurred coeval with the initiation of the Northern Hemisphere glaciation, documenting a close link between the development of the Indian monsoon and Northern Hemisphere glaciation.

印度洋季风系统的演化可通过印度洋赤道东部海域大洋钻探计划（Ocean Drilling Program）758站位的海底生物群——底栖有孔虫（benthic foraminifera）——的沉积记录得以揭示。在过去550万年（5.5 m.y.）间，该系统发生了剧烈变化，这一时间远晚于季风系统于1000万至800万年前（10-8 Ma）的起始阶段。约310万至250万年前（ca. 3.1-2.5 Ma）北半球大陆冰盖形成之前，全年适应高生产力环境的底栖有孔虫类群十分常见，这表明当时夏季（西南）季风强度较高且持续时长较长。约280万年前（ca. 2.8 Ma）的底栖生物群则以适应季节性食物供给剧烈波动环境的类群为主，这表明冬季（东北）季风（其对应的初级生产力相对较低）的持续时长与强度均有所增强，最终形成了与现代相似的季风系统。此次转变与北半球冰川作用的启动时间完全同步，证实了印度洋季风演化与北半球冰川作用之间存在紧密的内在关联。