74 Fossils-Mid

Fossils FOCUS Question What can fossils tell us about animals and plants that lived long ago?

化石能告诉我们生活在很久以前的动物和植物的什么信息?

What Is a Fossil? How do we know dinosaurs existed? In fact, how do we know anything about ancient plants and animals? We can look at rocks! Not just any rocks, though. We look at fossils. A fossil is anything left from an ancient living thing. It might be an animal's whole body, or just one part. It might be a nest full of eggs. It might be the shape of a leaf or animal footprints. It might even be really old poop! Fossils can teach us about plants and animals that lived a long time ago.

什么是化石?我们怎么知道恐龙存在过? 事实上，我们是如何了解古代动植物的呢? 我们可以看岩石!但不是普通的石头。 我们研究化石。化石是古代生物留下的任何东西。 它可能是动物的整个身体，也可能只是一部分。 它可能是一个满是蛋的窝。 它可能是一片树叶的形状，也可能是动物脚印的形状。 它甚至可能是非常古老的便便!化石可以告诉我们生活在很久以前的植物和动物。

Kinds of Fossils Most living things never become fossils. When they die, they get eaten or rot away. Once in a while, dead things are buried in the ground and slowly turn into rock. Over many, many years, they become fossils. There are two main types of fossils: body fossils and trace fossils. A body fossil is a living thing, or part of a living thing, that has turned into rock. Body fossils show the size and shape of living things. A trace fossil shows evidence of the activity of a living thing. Trace fossils can be nests, footprints, or poop that a living thing left behind.

化石的种类大多数生物永远不会变成化石。 它们死后，会被吃掉或腐烂。 偶尔，死去的东西被埋在地下，慢慢地变成岩石。 经过许多许多年，它们变成了化石。 化石主要有两种类型:尸体化石和痕迹化石。 尸体化石是一种生物，或生物的一部分，变成了岩石。 尸体化石显示了生物的大小和形状。 痕迹化石显示了生物活动的证据。 痕迹化石可以是巢穴、脚印或生物留下的粪便。

Bones, Teeth, and Shells A body fossil forms when a dead thing gets buried under layers of sediment. Sediment is made of tiny bits of loose material. It can be moved by wind or water. The hard parts of a dead thing are most likely to last and become fossils. That is why the most common body fossils are bones, teeth, shells, and the woody parts of plants. The weight of the layers above slowly presses down on the sediment. The loose sediment becomes solid rock. After thousands of years, all that is left of the dead thing is a fossil in rock.

当一个死去的东西被埋在沉积层下时，尸体化石就形成了。 沉积物是由微小的松散物质组成的。 它可以通过风或水来移动。 死去的东西的坚硬部分最有可能保存下来并变成化石。 这就是为什么最常见的尸体化石是骨头、牙齿、贝壳和植物的木本部分。 上层的重量慢慢地压在沉积物上。 松散的沉积物变成了坚固的岩石。 几千年后，死去的生物只剩下岩石中的化石。

Fossil Myths Myth: All fossils are from dinosaurs. Science: Countless plants and animals. including insects, have become fossils. Some of the most common fossils are from snails, clams, and other sea creatures with shells. Myth: Fossils are from animals or plants that do not exist anymore. Science: We find fossils of lots of animals and plant species that are still alive today! This fish has lived on Earth for 400 million years. You can see a live fish or a fossil of one from long ago. It has not changed much in all that time!

传说:所有的化石都来自恐龙。 科学:无数的植物和动物。 包括昆虫在内，都变成了化石。 一些最常见的化石来自蜗牛、蛤蜊和其他有壳的海洋生物。 传说:化石来自于已经不存在的动物或植物。 科学:我们发现了许多至今仍活着的动物和植物物种的化石!这种鱼已经在地球上生活了4亿年。 你可以看到一条活鱼或很久以前的鱼化石。 在这段时间里，它没有太大变化!

Feathers, Fur, and Skin How do we know what ancient animals looked like? Changing to rock usually destroys the soft parts of dead things. Sometimes the outside of an animal turns into a fossil. Paleontologists—scientists who study fossils—have found ancient feathers, fur, and even skin. These fossils are very special. They can tell us what an ancient animal looked like. This is a fossil of one of the first birds. Scientists have found fossils of these birds' feathers. Do You Know? Not all fossils are preserved in rock. Sometimes a dead plant or animal gets preserved in tree sap or in ice.

羽毛、皮毛和皮肤我们怎么知道古代动物长什么样? 变成岩石通常会破坏死去的东西柔软的部分。 有时动物的外表会变成化石。 古生物学家——研究化石的科学家——发现了古代的羽毛、皮毛甚至皮肤。 这些化石非常特别。 它们可以告诉我们古代动物的样子。 这是最早的鸟类化石之一。 科学家们已经发现了这些鸟类羽毛的化石。 你知道吗?并不是所有的化石都保存在岩石中。 有时，死去的植物或动物会被保存在树液或冰中。