The passage indicates that the Creiaceous period occurred（） A: in the early part of the Mesozoic era B: in the middle part of the Mesozoic era C: in the later part of the Mesozoic era D: after the Mesozoic era

The Mesozoic era is the age of "middle life" on Earth

Life arose during the ( ). A: paleozoic B: mesozoic C: cenozoic D: cambrian E: precambrian