15 Invertebrate Fossils-Mid

Invertebrate Fossils FOCUS Question What can we learn by studying the fossils of invertebrates?

无脊椎动物化石焦点问题通过研究无脊椎动物化石我们能学到什么?

Ancient Treasure In the 1880s, people in Canada were working on a new railroad. It would stretch across the entire country. They even had to build tracks over the massive Rocky Mountains. The railroad company sent a geologist named Richard McConnell to find a route through the mountains. Once there, he noticed strange shapes in the rocks. He had found thousands of fossils! They turned out to be some of the oldest animal fossils ever found. The rocks in this area became known as the Burgess Shale. By studying the fossils there, scientists have learned a lot about what Earth was like hundreds of millions of years ago.

19世纪80年代，加拿大人正在修建一条新铁路。 它将延伸到整个国家。 他们甚至不得不在巨大的落基山脉上修建轨道。 铁路公司派了一位名叫理查德·麦康奈尔的地质学家去寻找一条穿越山区的路线。 到了那里，他注意到岩石上有奇怪的形状。 他发现了成千上万的化石!它们是迄今为止发现的最古老的动物化石之一。 这一地区的岩石被称为伯吉斯页岩。 通过研究那里的化石，科学家们对数亿年前的地球有了很多了解。

Finding Invertebrate Fossils Fossils are traces of living things from long ago. When you think of fossils, you might think of dinosaur or fish bones. The Burgess Shale fossils are all invertebrates—animals without backbones. All fossils give us clues about the habitat where the plant or animal lived when it was alive. Imagine finding a coral fossil. A living coral's habitat is a warm ocean. So, the area where you found the fossil must have been under warm water long ago. Fossils of invertebrates are some of the best fossils for studying Earth's past. Science in Your World 1. Most body fossils came from bones, shells, teeth, and other hard materials. They are the most common. 2. Trace fossils came from tracks, nests burrows or other things plants and animals leave behind. They are less common. 3. Soft body fossils came from soft body parts such as flesh. They are very rare.

寻找无脊椎动物化石化石是很久以前生物的痕迹。 当你想到化石时，你可能会想到恐龙或鱼骨。 伯吉斯页岩化石都是无脊椎动物——没有脊椎的动物。 所有的化石都给我们提供了关于植物或动物活着时的栖息地的线索。 想象一下你发现了一块珊瑚化石。 活珊瑚的栖息地是温暖的海洋。 所以，你发现化石的地方一定是很久以前在温水下的。 无脊椎动物化石是研究地球历史的最佳化石之一。 科学在你的世界大多数尸体化石来自骨头、贝壳、牙齿和其他坚硬的物质。 它们是最常见的。2. 痕迹化石来自足迹、巢穴、洞穴或其他动植物留下的东西。 它们不太常见。3.柔软的身体化石来自柔软的身体部位，如肉。 它们非常罕见。

Why are invertebrate fossils helpful for looking at the past? Invertebrates are the most numerous animals on Earth. They include insects, worms, snails, and countless other animals. They also lived hundreds of millions of years before dinosaurs. The bones of big animals can get scattered over a wider area. Invertebrates are often small. Their fossils are more likely to be found whole. Also, soft bodies usually rot before they can become fossils. Many invertebrates have hard shells. Shells become fossils easily. For these reasons, invertebrates are the most common animal fossils. The easier it is to find a fossil the easier it is to study.

为什么无脊椎动物化石有助于回顾过去? 无脊椎动物是地球上数量最多的动物。 它们包括昆虫、蠕虫、蜗牛和无数其他动物。 它们还生活在恐龙出现的数亿年前。 大型动物的骨头会散落在更大的区域。 无脊椎动物通常很小。 它们的化石更有可能被完整地发现。 此外，柔软的物体通常在变成化石之前就腐烂了。 许多无脊椎动物有坚硬的外壳。 贝壳很容易变成化石。 由于这些原因，无脊椎动物是最常见的动物化石。 化石越容易找到，研究就越容易。

Invertebrate History The First Life Earth formed about 4.5 billion years ago. The first living things appeared about 3.8 billion years ago. They were simple cells like bacteria. These simple cells were the only life on Earth for millions of years! Then, about 540 million years ago, cells began to come together. They formed more complex living things. These were the first animals. In a short time, thousands of new species appeared. They quickly spread across the planet. This sudden development is called the Cambrian Explosion.

地球上的第一个生命形成于大约45亿年前。 第一批生物大约出现在38亿年前。 它们是像细菌一样的简单细胞。 数百万年来，这些简单的细胞是地球上唯一的生命!然后，大约5.4亿年前，细胞开始聚集在一起。 它们形成了更复杂的生物。 这些是最早的动物。 在很短的时间内，成千上万的新物种出现了。 它们迅速蔓延到整个星球。 这种突然的发展被称为寒武纪大爆发。

In the Sea Many kinds of invertebrates appeared during the Cambrian Explosion. They included animals that look like today's sea stars, snails, shrimp, and squid. The Burgess Shale is from this time. Scientists think a landslide along the coast buried many small aquatic invertebrates, which then became fossils. The Burgess Shale even has soft body fossils from animals such as worms. All these animals lived in warm, shallow seas. The floors were soft and mucky. That means that the place where the tall, snowy Canadian Rockies are today was once covered with warm salt water!

寒武纪大爆发期间出现了许多种无脊椎动物。 它们包括看起来像今天的海星、蜗牛、虾和乌贼的动物。 伯吉斯页岩就是这个时期的。 科学家们认为，沿海的一次滑坡掩埋了许多小型水生无脊椎动物，然后变成了化石。 伯吉斯页岩甚至有蠕虫等动物的软体化石。 所有这些动物都生活在温暖的浅海中。 地板又软又脏。 这意味着今天加拿大落基山脉的高雪山曾经被温暖的盐水覆盖!