动植物化石

Introduction
::导言

How does a fish get inside a rock? Did it grow there? Of course not, it's a fossil. We know this now, but that was not always the case. Fossils once inspired myths. Can you imagine finding a fossil of a dinosaur? What if you didn't know that dinosaurs were no longer living. That would be scary. 
::鱼是怎么进入岩石的?它在那里生长的吗?当然不是,它是一个化石。我们现在知道这一点,但并不总是这样。 化石曾经启发了神话。你能想象找到恐龙的化石吗?如果你不知道恐龙已经不在了,那又如何?那会很可怕。

The stories that were inspired by fossil dinosaurs are legendary. What do you think dinosaurs were mistaken for? All those fables of dragons were inspired by fossil dinosaur bones.   
::由化石恐龙所启发的故事是传奇的。 你认为恐龙被误认为什么? 所有这些龙的传说都是由化石恐龙的骨骼所启发的。

For thousands of years, people have found fossils. The fossils caused curiosity about Earth's past. How did these organisms live? What type of world did they live in? Fossils can tell us much about Earth's history. 
::数千年来,人们找到了化石。化石引起了人们对地球过去好奇。这些生物是如何生存的?他们生活在什么样的世界中?化石可以告诉我们关于地球历史的许多信息。

Two thousand years ago, fossils were found in China. At the time, they were thought to be dragon bones. We now know better. They are actually fossils. So how are bones and fossils different? 
::两千年前,在中国发现了化石。当时,它们被认为是龙骨。我们现在更了解它们。它们其实是化石。骨头和化石有什么不同?

What Are Fossils?
::什么是化石?

Fossils are preserved remains of organisms. They are preserved in two ways. They can be the actual remains of organisms. They can also be a trace of one. These organisms lived in Earth's past. 
::化石是有机体的残骸,它们以两种方式保存。它们可以是有机体的实际残骸,也可以是其中一种的痕迹。这些有机体生活在地球的过去。

Most fossils that are found are hard parts of organisms. These hard parts include teeth, bones, and shells. Examples of these kinds of fossils are pictured in  Figure  .
::大部分发现的化石都是有机物的硬部分。这些硬部分包括牙齿、骨头和贝壳。图中可图出这类化石的例子。

Traces of animals can be preserved in a few ways. One way might be a footprint. Another trace left by an ancient organism is a burrow they once dug. Another trace is the waste they leave behind. Examples of trace fossils are also shown in  Figure  .
::动物的踪迹可以用几种方式保存。 一种方式可能是足迹。 古代生物留下的另一种踪迹是它们挖掘后留下的洞穴。 另一种痕迹是它们留下的废物。 图中也显示了痕迹化石的例子。

 

How Fossils Form
::化石如何形成

The process by which fossils form is called  fossilization . Most fossils form in sedimentary rocks.
::化石形成的过程被称为化石化化,大多数化石形成沉积岩石。

Fossils in Sedimentary Rock
::沉积岩中的化石

Most fossils form when an organism dies. Their bodies get buried with sediment. Layers of sediment slowly build up. The sediment is buried with even more sediment. Over time, the sediment turns into sedimentary rock. The remains of the plant or animal also turns to rock. The remains are replaced by minerals. They literally turn to stone. This process is shown in  Figure   . 
::大部分化石是生物体死亡时形成的,它们的尸体被埋在沉积物中,沉积物层慢慢地积聚起来,沉积物被埋在更多的沉积物中,随着时间的推移,沉积物变成了沉积岩,植物或动物的残骸也变成了岩石,残骸被矿物质所取代,它们实际上变成了石头。这个过程在图中显示。

 

Other Ways Fossils Form
::其他方式 化石形式

Fossils may form in other ways. Fossils can be preserved almost completely. In this process, the organism doesn't change much. As seen below, tree sap may cover an organism. With time, the sap hardens. It turns to into amber. The original organism is preserved. This is very exciting for scientists.  They are able to study the DNA of the organism that no longer lives on Earth. Some animals have been found frozen in ice. Others have been found in tar pits after falling in.  
::化石可能以其他方式形成。 化石可以几乎完全保存。 在此过程中, 有机体不会发生多大变化。 如下文所示, 树苗可能覆盖一个有机体。 随着时间的推移, 树苗可能覆盖一个有机体。 树苗会变硬。 它会变成琥珀。 原始有机体会被保存。 这对科学家来说是非常令人兴奋的。 他们可以研究不再活在地球上的有机体的DNA。 一些动物已经被冰冻在冰中。 其他动物在坠入焦油坑后被发现。

Molds and casts are another way organisms can be fossilized. Have you ever walked in soft mud and left footprints? Once in a while, these traces of organisms can be preserved. In this case, nothing is left of the organism.  A mold is an imprint of an organism that is preserved in rock. The organism's remains break down completely. There is nothing left of the original plant and animal. What is left is a mold, or impression, of the original organism. This mold is then filled with other rock. The fossil that forms in the mold is called a cast. Molds and casts usually form in sedimentary rock. 
::模具和石膏是另一种生物可以被化化的方式。 你有没有用软泥和左脚脚印走过? 这些生物的痕迹可以保存一下? 偶尔,这些生物的痕迹可以保存下来。 在这种情况下,没有生物留下任何痕迹。 模具是保存在岩石中的有机体的印记。 有机体仍然完全碎裂。 原生植物和动物没有留下任何痕迹。 剩下的是原生生物的模具或印象。 这个模具会填满其他岩石。 模具中形成的化石被称为石。 模具和石膏通常以沉积岩的形式形成。

You can read about them in  Figure  .
::你可以在图中看到。

 

Why Fossilization is Rare
::为什么化石化是稀有的

Conditions must be just right. That's why fossils are rare. Why don't many more dead plants and animals turn into fossils?
::所以化石是稀有的 为什么更多的死植物和动物 变成化石?

Many times, dead animals get eaten by other animals. When this happens nothing can be preserved. Insects may break down the remains. Others dead plants and animals may get broken down by the elements.
::许多时候,死动物被其他动物吃掉。当事情发生时,没有任何东西可以保存。昆虫可能会把残骸打碎。其他死动植物可能会被元素分解。

Fossils mostly come from the hard parts of animals. Just because a part is hard is still no guarantee is will become a fossil. Fossils are even less likely to come from soft organisms. Fossils of bacteria to jellyfish are very rare.  
::化石大多来自动物的硬部分。 仅仅因为一部分硬部分是硬的,仍然不能保证它将成为化石。 化石更不可能来自软有机体。 细菌对水母的化石非常罕见。

Learning from Fossils
::从化石中学习

Many plants and animal species have lived on Earth. Most are no longer alive. Only a tiny number of species still live on Earth. If not for fossils, we would know little about species that did not survive. Fossils provide evidence. They give us clues to past life on Earth. They tell us that life on Earth has changed over time. Fossils in younger   look like animals and plants that are living today. Fossils in older rocks are less like living organisms. 
::许多植物和动物物种都生活在地球上,大部分已不复存在。只有极少数物种仍然生活在地球上。如果没有化石,我们将对无法生存的物种知之甚少。化石提供了证据。它们为我们提供了地球上过去生命的线索。它们告诉我们,地球上的生命随着时间的变化而发生变化。年轻时的化石看起来像今天生活的动物和植物。老岩石中的化石不像活生物体。

Fossils can also tell us about how plants and animals lived in the past. Was it land or marine? Was the water shallow or deep? Fossils can even provide clues to ancient climates. They can tell us if it was warm or cold. Maybe it was cold or hot? Some places that are now cold were once warm. Some places that are now hot and dry were once wet and cool. Fossils provide a window into the past.
::化石也可以告诉我们过去植物和动物是如何生活的。是陆地还是海洋?水是浅的还是深的?是浅的还是深的?化石甚至可以提供古代气候的线索。它们可以告诉我们是暖还是冷。可能是冷还是热?有些现在冷的地方曾经是暖的。有些现在炎热和干燥的地方曾经是湿的和冷的。化石为过去提供了一个窗口。

Fossil Clues
::化石结壳

Fossils give clues about major geological events. Fossils can also give clues about past climates.
::化石可以提供重大地质事件的线索。 化石也可以提供过去气候的线索。

• Fossils of ocean animals on the top of a mountain? Ocean animals have been found on the Earth's tallest mountain. It's hard to believe, but it is true. These fossils were found at the top of Mt. Everest. Mt. Everest is the highest mountain on Earth. These fossils showed that this entire area was once at the bottom of a sea. It can only mean that Mt. Everest was uplifted. In fact, the entire Himalaya mountain range was raised. It was forced up from the collision of two continents. An example is shown in the  Figure  .
  ::山顶的海洋动物的化石? 海洋动物是在地球上最高的山上发现的。 很难相信, 但确实如此。 这些化石是在珠穆朗玛峰顶部发现的, 珠穆朗玛峰是地球上最高的山。 这些化石表明整个区域曾经一度处于海底。 这只能意味着珠穆朗玛峰被提升了。 事实上, 整个喜马拉雅山脉被提升了。 它被迫从两个大陆的碰撞中上升。 图中的例子就是一例。

• Fossils of plants are found in Antarctica. Now, Antarctica is almost completely covered with ice. Plants do not grow in Antarctica. According to fossils, they once did. This means that Antarctica was once much warmer than it is now. These fossils tell us about Antarctica's past climate. 
  ::南极洲有植物的化石。现在,南极洲几乎完全被冰覆盖。南极洲的植物并不生长。根据化石,它们曾经存在过。这意味着南极洲曾经比现在更暖和。这些化石告诉我们南极洲过去的气候。

 

Lesson Summary
::经验教训摘要

• Fossils are preserved remains or traces of organisms. They lived in Earth's past. Most fossils form in sedimentary rock. Fossils can also be preserved in other ways. It’s rare for any given organism to become a fossil.
  ::化石被保存在残骸或生物的痕迹中,它们生活在地球的过去。 大部分化石都是沉积岩中的化石。 化石也可以以其他方式保存。 任何特定生物都很少成为化石。

• Fossils are the best form of evidence about the history of life on Earth. Fossils also give us clues about Earth's past. They can tell us about major geological events and past climates. 
  ::化石是地球生命史的最佳证据形式。 化石也为我们提供了地球过去的一些线索。 他们可以告诉我们重大地质事件和过去气候。

Lesson Review Questions
::经验回顾问题

Recall
::回顾

1. What are fossils?
   ::什么是化石?

1. Give examples of trace fossils.
   ::举例说明痕量化石。

1. Why are most preserved remains teeth, bones, or shells?
   ::为什么大部分被保存起来的都是牙齿、骨头或贝壳?

1. Describe how fossils form in sedimentary rock.
   ::描述化石如何在沉积岩中形成。

1. Why is fossilization rare? 
   ::为什么化化化稀罕?

Apply Concepts
::应用概念

6. Create an original diagram to explain the concept of index fossil. Your diagram should include sedimentary rock layers and fossils.
   ::创建用于解释索引化石概念的原始图表。 您的图表应该包含沉积岩层和化石 。

Think Critically
::仔细仔细思考

7. Compare and contrast the fern fossil in  Figure   and the fossil dinosaur tracks in  Figure  . Infer what you might learn from each type of fossil.
   ::比较和对比图中的生化石和图中的化石恐龙足迹。

7. Earth’s climate became much cooler at different times in the past. Predict what fossil evidence you might find for this type of climate change.
   ::地球的气候在过去的不同时期变得更冷酷。 预测你可能找到的这类气候变化的化石证据是什么。

Points to Consider
::需要考虑的要点

Fossils can help scientists estimate the ages of rocks. Some types of evidence show only that one rock is older or younger than another. Other types of evidence reveal a rock’s actual age in years.
::化石可以帮助科学家估计岩石的年代。 某些类型的证据表明,只有一块岩石比另一块岩石年长或更小。 其他类型的证据表明岩石的实际年代是年长的。

• What evidence might show that one rock is older or younger than another?
  ::哪些证据可以证明一块岩石比另一块岩石年长或更小?

• What evidence might reveal how long ago rocks formed?
  ::什么证据能揭示岩石形成多久了?