爱爵爷与巨型恐龙（Attenborough and The Giant Dinosaur）

视频地址：https://www.bilibili.com/video/av4534706/

附：教材P49，Lesson Review 参考答案

1-4 C,D,A,B

5. Precambrian time, the Paleozoic era, the Mesozoic era, and the Cenozoic era.

6. Single-celled prokaryotes dominated Earth during Precambrian time. Plants, fungi, and air-breathing animals colonized land during the Paleozoic era. Dinosaurs dominated Earth during the Mesozoic era. Mammals have dominated Earth during the Cenozoic era.

7. The atmosphere has a much greater percentage of oxygen now than it did before.

Cyanobacteria.

8. Fossils of an organism that went extinct before this organism evolved would be found only in the very bottom rock layer, beneath the fossil shown, because that rock layer is older and formed first.