"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.
"It took many years for the dinosaur bones to become fossils.
Finally scientists dug the fossils out of the sedimentary rock.
They had to be very careful not to break the rock.
After they cleaned the rock, what did they find?" asked Miss Bennett.
"A fossil!" everybody answered.
They all held up their slabs of clay.
On each one was a handprint.
"Your handprint is not your actual hand," said Miss Bennett.
"But we can still see that it was a hand.
In the same way, fossils are not the actual bones of a dinosaur."
"Is that why you said that the dinosaur bones we saw are not real?" called out Eric.
"Yes, you are right." Miss Bennett nodded.
"Remember, the original bones are replaced by rocklike minerals," Miss Bennett explained.
"So a fossil is just a model of the original bone, like your handprint.
And the dinosaur bones in the exhibit are models of the fossils."
"Thank you, Miss Bennett," the children said together.
"We learned a lot today."
"Come back anytime!" Miss Bennett waved.
"There is still more to learn about the world of fossils."