她说有两层显示了这种联系，一层有大约3万年历史，另一层3万5千年。
She says there are two layers showing the association, one about 30,000 years old, the other 35,000 years old.
这个有着6550万年历史的地层分离了白垩纪的化石和第三纪的化石。
This 65.5-million-year-old layer of Earth separates fossils of the Cretaceous period from those of the Tertiary period.
有着2200万年历史的Mush植物群会和Chilga 植物群本质相同吗？
Will the 22-million-year-old Mush flora be essentially the same as Chilga floras?
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