and Fuels OSSIIS Vocabulary Process Skill

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1 \ Vocabulary fossil, C22 amber, C22 fuel, C26 OSSIIS and Fuels Process Skill The objects captured in this piece of amber were once alive. Now they are fossils. Fossils tell us the story of life on Earth billions of years ago. Can you imagine how this might have happened? You experiment when you perform a test to support or disprove a hypothesis. C2O

2 L C 0, Explore Activity How Are Fossils Formed? Procedure D Squeeze a small amount of glue into the spoon. Let the glue set for a few hours. EJ Place one slice of carrot on top of the glue. Slowly add more glue until the carrot slice is completely covered. Place the spoon on a paper towel. Put the other slice of carrot next to the spoon. Q Observe Compare the carrot slices. Describe their color and appearance. Materials large plastic spoon clear glue 2 slices of carrot paper towel Drawing Conclusions How did the glue change the carrot slice? Predict Over time, will the carrot slice in the glue change more than the other carrot slice? Why? Going Further: Experiment Place both carrot slices in a safe, dry place for two to ten days. Observe how they changed. Was your prediction correct?

3 V Read to Learn Main Idea Fossils teach us about Earth's past. A fossil (FAHS-uhl) is the imprint or remains of something that lived long ago. People have found fossils that are more than three billion years old! First, plants and animals die. Their soft parts decay or are eaten. The hard parts, such as teeth, bones, and shells, last longer. These parts might become fossils. This woman is looking for fossil bones preserved in rocks. \w Are Fossils For Most fossils are found in sedimentary rocks. Remember, these rocks form when silt, sand, mud, and other materials pile up and get cemented together. Sometimes these materials cover the remains of living things. This happens gently and quickly. The remains may become fossils, as rocks form around them. Fossils are also found in amber (AM-buhr). Amber is hardened tree sap. Tree sap is a sticky liquid that can harden like glue. When an insect gets stuck in tree sap, it may become a fossil in amber.

4 X -V One of these fossils is a cast. The other fossil is a mold. Can you tell which fossil is the cast and which fossil is the mold? The fossil on the left is the mold, and the fossil on the right is the cast. Shallow prints or marks in solid rock are called imprints. Living things made the imprints. They pressed on the materials that later turned into rock. Shells often leave fossils called molds. A mold is an empty space in rock where something once was. Shell molds form after shells are buried in sand or mud. As water seeps in, it washes away the shells. Shell-shaped spaces are left. A cast is a fossil made inside a mold. A cast can form when minerals seep into a mold. As the minerals harden, they form a copy of the mold's shape. FOR SCHOOL OR HOME Imprint Clues 1. Roll modeling clay into a thick, flat layer. Gather several small objects. 2* Make a Model Press an object into the clay. It should make an imprint. Carefully remove the object. 3. Repeat step 2 with the other objects. 4. Infer Look at the imprint models that your classmates made. Try to figure out which objects they used. 5. Share your ideas with the class. JJIUMCI Sequence of Events What is one way that fossils can form? C23

5 What Do Fossils Tell Us About the Past? Fossils help us learn about what Earth was like long ago. They tell us about the plants and animals of the past. Look at the fossil bone shown at right. The bone is very different from the bones of animals alive today. It came from a dinosaur that lived millions of years ago. Everything we know about dinosaurs comes from studying their fossils. This man is standing next to the fossil leg of a supersaurus. Scientists estimate that supersaurus may have stood 16.5 meters (54 feet) tall! Very little is known about this dinosaur because very few fossil bones have been discovered. The diagram shows which bones have been found. Fish fossils have been found under dry land and even inside mountains. C 24 Triceratops is the best known horned dinosaur. It lived during the Cretaceous period.

6 Compare the woolly mammoth and elephant. How are they alike? How are they different? Fossils can also tell how Earth has changed. Fish fossils have been found under dry land. How must Earth have changed for this to happen? Fossils tell us how life on Earth has changed. Many types of animals that lived in the past, such as dinosaurs, are not alive today. Look at the picture of another animal from the past, the woolly mammoth. Does it remind you of an animal you see today? The woolly mammoth may be an ancient relative of the elephant. Earth's plants have also changed. Ferns are some of Earth's oldest plants. Plants that make flowers came later. How has life on Earth changed over time? C 25

7 V >^"**. What Are Fossil Fuels? Cars, trucks, and airplanes need fuel (FYEW-uhl) in order to run. A fuel is a material that is burned for its energy. Oil products, such as gasoline, are fuels. Coal and natural gas are, too. These fuels are examples of fossil fuels. Fossil fuels formed from the remains of plants and animals from long ago. \s Where do fossil fuels come from? How Coal Forms Millions of years ago, swamps covered large parts of Earth's land. When swamp plants died, they sank to the bottom. Diagrams Layers of decayed plants formed a soft material called peat. Over time the peat was buried under layers of mud and sand. The mud and sand turned to rock. Slowly the peat changed into coal. Describe how swamp plants changed to coal. C26

8 Why It Matters Fossils tell a story. The story is about Earth's history. It is a very long story that includes many changes. There can be changes in land and water. There can be changes in the weather. There can also be changes in living things. If you learn about the changes of the past, you can predict changes in the future. Visit to do a research project on fossils. Think and Write 1. What is a fossil? 2. Describe three types of fossils. 3* How do we know about dinosaurs? 4. What are fossil fuels? Give an example. 5. Critical Thinking We know a lot about dinosaurs. Why can we only hypothesize about what colors they were? MATH LINK Make a bar graph. The table shows the lengths of different dinosaurs. Make a bar graph that shows these lengths. You may choose to research more about these dinosaurs. Dinosaur Apatosaurus Allosaurus Triceratops Troodon Ultrasaurus Length 23 meters 1 2 meters 8 meters 2 meters 30 meters WRITING LINK Write a letter. Imagine that you are a woolly mammoth. Write a letter to an elephant in the future. What questions might a woolly mammoth ask an elephant? SOCIAL STUDIES LINK Write a report. Research alternative or replacement heat sources. These include geothermal, nuclear and solar energy. TECHNOLOGY LINK At the Computer Visit for more links. C27