Age of the Vastan lignite in context of some oldest cenozoic fossil mammals from India
Age of the Vastan lignite in context of some oldest cenozoic fossil mammals from India
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印度一些最古老的新生代哺乳动物化石中瓦斯坦褐煤的年龄
DOI：
10.1007/s12594-010-0076-y
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发表时间：
2010
影响因子：
1.3
通讯作者：
P. Saraswati
中科院分区：
文献类型：
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作者：
Jahnavi Punekar;P. Saraswati
近年来，在瓦斯坦褐煤矿区(北纬21°25‘47“；东经73°07’30”)发现了高度多样化的哺乳动物和其他大陆脊椎动物化石组合。它在检验哺乳动物迁入或迁出印度的古生物地理学假说方面的重要性，需要确定该序列的确切年龄。布氏有孔虫是本区唯一的年龄诊断有孔虫。本种广泛分布于印度沉积盆地，用于标记早期始新世地层。通过对两个亚种的区分，进一步进行了生物地层的精细化。它们在剖面上的重合暗示了基本的崔氏时代和浅水海底带SBZ 10(最有可能是下部)。对库奇本种的研究表明，进化上先进的亚种Nummuites burdigalensis cantabricus的出现是在中崔西时代(SBZ 11)。与最近的一些报告相反，这项研究排除了在矿区出现蓝线虫或任何其他伊利尔迪亚有孔虫的可能性。
A highly diverse assemblage of mammal and other continental vertebrate fossils is reported in recent years from Vastan lignite mine (21°25′47″ N; 73°07′30″ E). Its importance in testing palaeobiogeographic hypothesis of mammalian dispersal in to or out of India has necessitated a definite age of the sequence. Nummulites burdigalensis is the only age diagnostic foraminifer in the section. This species is widespread in the Indian sedimentary basins and used to mark Early Eocene strata. In the present study two subspecies of Nummulites burdigalensis, viz., Nummulites burdigalensis burdigalensis and Nummulites burdigalensis kuepperi, are distinguished which led to further biostratigraphic refinement. Their concurrence in the section implies basal Cuisian age and shallow benthic zone SBZ 10 (most likely the lower part). The examination of this species from Kutch indicates the occurrence of evolutionarily advanced subspecies Nummulites burdigalensis cantabricus of middle Cuisian age (SBZ 11). Contrary to some recent reports, the study rules out the occurrence of N. globulus or any other Ilerdian foraminifer from the mine section.