The World of Fossils

Look how big its feet are! ” Eric pointed. “ How did they find all the bones?” Dana raised her hand. All the kids in the class were looking at a dinosaur exhibit. Do you want to know a secret?” Miss Bennett, the museum guide, said in a low voice. “ Those are not real dinosaur bones! ” But . . . but . . . but, ” Eric stuttered. “ So dinosaurs never existed?” Carol asked timidly.

Of course they existed! ” Miss Bennett laughed. “ But those bones are not the original bones. Follow me and I will explain. ” The class followed her into another room. “ First, who knows where those bones came from?” Miss Bennett asked. From dead dinosaurs?” Eric answered. “ They come from fossils! ” Carol said.

You are both right. The dinosaur's dead bones turned into fossils. ” Miss Bennett switched on a projector. She pointed at the dinosaur on the screen. “ Look at this dinosaur. Usually, when a dinosaur dies, it decays or another animal eats it. But sometimes the dinosaur is buried before it gets destroyed. Slowly the flesh and skin of the dinosaur rot away. Only the bones are left.

Then more and more mud and sand cover the bones. The mud and sand, which are called sediment, press down on the bones. The sediment has water in it. The water has minerals. The minerals soak into the dinosaur bones. Slowly the bone material is replaced by the minerals. The bones become hard rock. Now they are fossils. This process takes a very long time.

It takes thousands and thousands of years for the sediment to form heavy layers. These heavy layers turn into sedimentary rock around the fossils. So most fossils are found in this rock. ” When the slide show was over, Miss Bennett gave everyone a slab of clay. Let's try a simple experiment, ” she said as she held up her hand. “ Place your hand on the clay.

Pretend that your hand is a dead dinosaur covered with sand and mud. Press down on your hand and imagine it is being covered by more layers of sand and mud. Imagine the sediment keeps pressing for thousands, even millions of years! ” Ouch! My hand hurts, Miss Bennett! ” Eric said. Everyone laughed, and Miss Bennett continued her explanation.