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内蒙古二连盆地呼和勃尔和地区古近系包括3个组:脑木根组、阿山头组和伊尔丁曼哈组,从中可以划分出12个含哺乳动物化石的层位,其中脑木根组4个,阿山头组6个,伊尔丁曼哈组2个.研究表明,美国中亚考察团在这一地区划分的“呼尔井组”实际上是伊尔丁曼哈组,而“伊尔丁曼哈组”则为阿山头组.根据最新的古地磁资料,对相关组的时代和哺乳动物分期的延续时间进行了重新厘定,指出脑木根组上部包含了早始新世地层,阿山头组绝大部分属于早始新世,而不是过去认为的中始新世.将格沙头期、伯姆巴期和阿山头期分别与国际地质年表的坦尼特期、伊普里斯期早期和伊普里斯期中晚期至鲁帝特期最早期相对比,同时认为它们分别与北美古近纪提法尼期晚期至克拉克福克期、华沙溪期早期和华沙溪期中晚期及勃里吉期大部相当.古近纪早期,哺乳动物群演替以新科出现和属种更替为主,与这一时期大多数情况下气候的逐渐变化相对应;而众多目一级现代哺乳动物类群在始新世之初的突然出现则很可能与发生在古新世-始新世之交的高温事件有关.
Inner Mongolia Erlian Basin Hoh Boer and the Paleogene include three groups: the Yamugen Formation, the Ashantu Formation and the Ildefjordah Formation, which can be divided into 12 layers of mammalian fossils, including the brain root 4 in the group, 6 in the Aoshantu group and 2 in the Ildefjorda group. The study shows that the “Hu’ai Well Group” divided by the Central Asian delegation in this region is actually the Erdin-Manchu group , While the “Erdinger Mana Formation” is the Ashantu Formation.According to the latest paleomagnetic data, the age of the relevant groups and the duration of the mammalian staging are redefined, indicating that the upper part of the N. benthami group contains early For the Eocene strata, most of the A-Shantou Formation belonged to the Early Eocene rather than the Middle Eocene, which was considered in the past.When the Gesha head, Bombas and Aoshan head periods were respectively compared with the Taney The epoch, the epicenter of early Ypres and the period from the middle of late Epirus to the early period of the Luthotic period, respectively, at the same time they are thought to be respectively related to the period from the late Paleogene to the Clarke-Fogg period in North America, the Warsaw epoch and Warsaw In the middle and late stages of Brooks and most of the Brigitch, the succession of mammalian herds in the early Paleogene Now and the genus alternation, corresponding to the gradual change of climate in most of the cases in this period; and the sudden emergence of many modern Mammal fauna at the beginning of Eocene is likely to be related to the paleo- - Eocene at the turn of the hot events.