Birbal Sahni Institute of Palaeobotany, Lucknow, India.
PLoS One. 2013;8(1):e53177. doi: 10.1371/journal.pone.0053177. Epub 2013 Jan 22.
A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 10°-15°N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa.
本文描述了产自印度阿萨姆邦马库姆煤田晚渐新世沉积物中的番荔枝科新化石叶印痕 Alphonsea Hk. f. & T.。这是南亚第三纪岩石中 Alphonsea 化石的首个真实记录。晚渐新世是全球最后一次显著温暖气候的时期，而化石产地的古纬度在 10°-15°N。已知的古植物群和沉积学研究表明，该地区的沉积环境为河流-海洋三角洲，具有红树林、河流、沼泽和湖泊等多种沉积环境。在沉积时期，印度板块和欧亚板块之间的缝合尚未完全完成，这为植物迁移提供了便利。到晚渐新世/早中新世末期，缝合完成，导致该属迁移到东南亚，目前在东南亚大量生长。本研究与先前发表的古植物群和分子系统发育数据一致。该研究还表明，印度板块不仅是冈瓦纳古陆到亚洲的北行过程中的生物运输者，也是几个植物类群起源的地方。
