11 How a fossil is made

HOW A FOSSIL IS MADE Fossils are the remains of things that have been dead for millions of years. All sorts of life forms have fossilised, from spectacular Stegosaurus skeletons to tiny ammonite shells. Fossils help us understand how life on our planet has changed over millions of years. Scientists called palaeontologists dig up and study fossils. STEP 1 A creature dies and its body sinks into the mud by a river. STEP 2 The creature is buried in layers of mud, sand, and ash over a period of millions of years.

化石是几百万年前死去的东西的残骸。 各种各样的生命形式都变成了化石，从壮观的剑龙骨架到微小的鹦鹉螺壳。 化石帮助我们了解数百万年来地球上的生命是如何变化的。 被称为古生物学家的科学家挖掘并研究化石。 1 .生物死亡，尸体沉入河边的泥中。 在数百万年的时间里，这种生物被埋在泥土、沙子和灰烬层中。

STEP 3 The skeleton of the creature turns from bone to stone. STEP 4 The fossilised creature is uncovered by palacontologists. They dig out the fossil and coat it in plaster to protect it. The fossil then sent to a laboratory to be studied or to a museum to be displayed. Types of fossil Body fossils, such as bones, teeth, and shells Petrified fossils, which are soft tissues, such as muscle and leaves Trace fossils, such as fossilised footprints, which tell scientists about a creature's behaviour Coprolites-fossilised poos!

3 .生物的骨骼从骨头变成石头。 4 .古生物学家发现了生物化石。 他们把化石挖出来，涂上石膏以保护它。 然后把化石送到实验室进行研究或送到博物馆展出。 化石的种类身体化石，如骨骼、牙齿和贝壳石化化石，是软组织，如肌肉和树叶痕迹化石，如脚印化石，告诉科学家一个生物的行为粪化石——粪便化石！