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Part 4: Reptiles

Amphibians had to live near water, but the first reptiles, 300 million years ago, could live far from bodies of water. They did not have to spend the early part of their lives in water, and they did not need to lay their eggs in water. Therefore, reptiles could spread much farther onto the land.

Reptile Traits

Reptiles can live in many places amphibians cannot. They can live in or near water, but they can also live in forests, deserts, and other dry places away from water. They have dry skin which is covered with scales, their lungs are good, and they do not need to be near water in order to reproduce. Their eggs are fertilized inside the body instead of in the water. Also, the eggs are covered with a thick leathery skin which does not lose water easily, and there is food inside the egg. Reptiles also do not have metamorphosis. A newly hatched reptile looks very much like its parent.

However, reptiles are similar to amphibians in some ways. They lay eggs, as amphibians do. Like amphibians, most reptiles do not care for their young. After laying the eggs, they leave. Also, reptiles, like amphibians, are cold-blooded, which means they are the temperature of the air around them. Many reptiles, however, will sit somewhere warm to raise their body temperature, or in the shade in order to cool themselves down.

Reptile Groups

There are three main groups of reptiles. One group is the lizards and snakes. Although snakes do not have legs, they evolved from lizards, which have legs. The second group is the turtles and tortoises, which have a heavy shell that is attached to the skeleton. The third group is the crocodiles and alligators (the crocodilians). The last two groups are generally found in or near the water.

Scientists believe that mammals, dinosaurs, and birds all evolved from reptiles. Some scientists even group birds in the same class as reptiles because of this.

Homework

Questions: For your first assignment of the week, answer these questions in complete sentences on a sheet of loose-leaf paper, with a proper header:

1. Give three reasons why reptiles can live on dry land more easily than amphibians.
2. In a sentence, give two ways reptiles and fish are similar.
3. Name three groups of reptiles.
4. Do you think any reptiles live in the coldest parts of the Earth, such as the Arctic? Explain your answer.

Notes: For your second assignment of the week, in your journal on the next clean page, write the vocabulary words from this section and their definitions.

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This page last modified August 15, 2002

Copyright ©2000 Delia Marshall Turner. All rights reserved.

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