Fossils .
化石。
Fossils are the remains of animals or plants
化石是动物或植物的遗骸
that lived a very long time ago.
那是很久以前的事了。
All the dinosaurs died out, but we can learn about them with their fossils.
所有的恐龙都灭绝了，但是我们可以通过它们的化石来了解它们。
Sometimes, a fossil is made when an animal dies in mud or sand.
有时，当动物死在泥或沙子里时，化石就形成了。
The animal is then buried by the mud or sand.
然后动物被泥土或沙子掩埋。
The soft parts of the animal rot away.
动物柔软的部分腐烂掉了。
The hard parts like bones, teeth or shells remain.
骨头、牙齿或贝壳等坚硬的部分仍然存在。
Over a very long time, the hard parts turn into rock.
经过很长一段时间，坚硬的部分变成岩石。
The bones, teeth or shells turn into rock.
骨头、牙齿或贝壳变成岩石。
They are now fossils.
它们现在变成了化石。
Another type of fossil is made by making a print in mud.
另一种化石是通过在泥中打印而成的。
Plants or animals can make prints in mud.
植物或动物可以在泥中打印。
The mud dries out, it becomes hard and the print remains.
泥浆变干，变得坚硬，留下印记。
Over a very long time, the mud turns into rock.
经过很长一段时间，泥浆变成了岩石。
The rock is now a fossil.
这块石头现在是化石。