19.4古生代生命史
章节大纲
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Okay, so you may not recognize the Precambrian. How about the Paleozoic?
::好吧,你可能认不出Precambrian了,Paleozoic怎么样?Animals from the early Paleozoic looked pretty bizarre! The creature on the right is called Anomalocaris, a name that means “strange shrimp”. The creature on the left, Opabinia, had five eyes, and a long nose like a vacuum cleaner hose. These early arthropod relatives were found as fossils in the Burgess Shale in Canada
::早期Paleozoic的动物看起来很奇怪!右边的动物叫Anomolocaris, 意思是“虾 ” 。 左边的动物Opabinia有五只眼睛,长鼻子像吸尘器管一样长鼻子。 这些早期的节肢动物亲戚在加拿大的Burgess Shale被发现为化石。Paleozoic Era
::Paleozoic 时代The first period of the Paleozoic Era was the Cambrian. By the beginning of the Paleozoic, organisms evolved shells. Shells could hold their soft tissues together. Shells could protect them from predators and from drying out. Some organisms evolved external skeletons. These are called exoskeletons . Organisms with hard parts also make good fossils. Fossils from the Cambrian are much more abundant than fossils from the Precambrian.
::Paleozoic时代的第一个时期是Cambrian。在Paleozoic时代开始时,生物进化了壳体。壳体可以将软组织放在一起。壳体可以保护它们免受掠食者和干燥。一些生物体会演变出外部骨骼。这些外骨骼被称为Exoskeletons。硬零件的有机体也会成为好化石。来自Cambrian的化石比来自Precambrian的化石要丰富得多。The Cambrian Explosion
::坎布里安爆炸The warm, humid climate of the early Cambrian was good for life. There was a tremendous increase in biodiversity , and all modern phyla of animals appeared within the Cambrian period. The evolution of hard shells allowed more fossils from this time period to be preserved. For these two reasons, this time period is called the Cambrian Explosion .
::早期Cambrian的温暖潮湿气候对生命有利。 生物多样性大幅增长,所有现代动物植物都出现在Cambrian时期。 硬壳的进化使得从这一时期以来有更多的化石得以保存。 由于这两个原因,这一时期被称为Cambrian爆炸。With so much diversity, complex ecosystems could develop. All of this life was in the seas.
::有如此多的多样性,复杂的生态系统可以发展,所有的生命都在海洋中。The Paleozoic Continues
::Paleozoic 继续Paleozoic seas were full of worms, snails, clams, trilobites, sponges, and brachiopods. Organisms with shells were common.
::帕利奥佐科海充满了蠕虫、蜗牛、蛤、三叶虫、海绵和无脊椎动物。 含有炮弹的有机体是司空见惯的。The first fish were jawless, with a simple internal skeleton. Some groups of fish evolved external armor. Later in the Paleozoic, fish evolved jaws and many other adaptations for ocean life. Some, like sharks, skates, and rays, maintained skeletons of cartilage. Other fish evolved a bony skeleton. Bony fishes make up the majority of fish species in the oceans today. Pictured below is some of the diversity of Earth's oceans ( Figure ).
::第一种鱼是没有下巴的,有简单的内骨骨骼。有些鱼群进化了外部盔甲。后来在Paleozoic,鱼类进化了下巴和海洋生物的许多其他适应。有些鱼,如鲨鱼、滑板和射线,保存了软骨。其他鱼类进化了一个骨骼骨骼。如今,骨灰鱼占了海洋鱼类的大多数。下面是地球海洋(图示)多样性的一些图象。Mudskippers are fish that are able to walk short distances. Moving Onto Land
::向陆地移动An organism that lives in water is supported by the water. It does not need strong support structures. It also does not need to be protected against drying out. This is not true of land. Moving from the seas to land required many adaptations.
::生活在水中的有机体得到水的支持,不需要强大的支撑结构,也不需要保护,防止干涸,土地的情况并非如此,从海洋向陆地的迁移需要许多调整。Algae had covered moist land areas for millions of years. By about 450 million years ago, plants began to appear on land. Once there were land plants, animals had a source of food and shelter. To move to land, animals needed strong skeletons. They needed protection from drying out. They needed to be able to breathe air. Eventually they had skeletons, lungs, and the other the adaptations they needed moved onto the land.
::藻类已经覆盖了数百万年的潮湿土地面积。大约在4.5亿年前,植物开始出现在陆地上。一旦有了陆地植物,动物就有了食物和栖身之地。迁移到陆地,动物需要坚固的骨骼。它们需要保护,以免干涸。它们需要呼吸空气。最终,它们有骨骼、肺和其他需要适应的植物转移到了陆地上。Halkieria, or scale worms, are an example of a fossil life from the Cambrian. One group of fish evolved into amphibians. Insects and spiders were already land dwellers by the time amphibians appeared.
::有一种鱼类演变成两栖动物,在两栖动物出现时昆虫和蜘蛛已经是陆地居民。Mass Extinctions
::大规模灭绝The eras of the Phanerozoic Eon are separated by mass extinctions . During these events, large numbers of organisms became extinct very rapidly. There have been several extinctions in the Phanerozoic. Two mass extinctions stand out more than the others. One took place at the end of the Paleozoic. The other took place at the end of the Mesozoic.
::Phanerozoic Eon的时代因大规模灭绝而分离开来,在这些事件中,大量生物迅速灭绝,在Phanerozoic有几次灭绝,有两次大规模灭绝比其他的更突出,一次发生在Paleozoic的末端,另一次发生在Mesozoic的末端。Permian Extinction
::永久灭绝Between the Paleozoic Era and the Mesozoic Era , about 252 million years ago, was the largest mass extinction known. At the end of the Permian, nearly 95% of all marine species died off. In addition, 70% of land species became extinct. Most scientists believe that a series of enormous volcanic eruptions released carbon dioxide and other greenhouse gases into the atmosphere . This led to intense and changed the chemistry of the ocean, so many organisms could not survive.
::大约在2.52亿年前的Paleozoic Era和Mesozoic Era之间,是已知最大的大规模灭绝。在Permian的末期,近95%的海洋物种死亡。此外,70%的陆地物种灭绝了。大多数科学家相信,一系列巨大的火山爆发将二氧化碳和其他温室气体释放到大气中。这导致了海洋化学的强烈变化,因此许多生物无法存活下来。Summary
::摘要- In the Cambrian there was an explosion of life. This explosion was in number and in diversity.
::Cambrian有一次生命爆炸,这次爆炸的数量和多样性。
- At the beginning of the Paleozoic, all life was in the seas. Later in the Paleozoic, life colonized the land.
::在Paleozoic的初期,所有的生命都在海洋中,后来在Paleozoic,生活使这片土地殖民化。
- To colonize land, animals need to be able to keep themselves together. They need to keep from drying out. They need to be able to breathe air.
::要殖民土地,动物必须能够保持团结,必须避免干涸,必须能够呼吸空气。
- At the end of the Permian was the largest known extinction in Earth history.
::在波尔米安群岛末期 是地球历史上已知最大的灭绝
Review
::回顾- What evolved during the Cambrian that was important for the evolution of life and what is its purpose?
::在坎布里安时期,什么变化对生命的演变很重要? 它的目的是什么?
- What does a sea creature need to have if it's going to colonize the land?
::如果一个海洋生物要殖民这片土地 需要什么?
- What brought about the Permian extinction?
::是什么导致了波尔米亚的灭绝?
- In the Cambrian there was an explosion of life. This explosion was in number and in diversity.
