Dinosaurs and fossils
Millions of years ago, the Earth was home to giant animals that no longer exist: the dinosaurs. Nobody has seen them in person and yet we know what they looked like, what they ate and even how they looked after their eggs. How is that possible? Thanks to very special clues: fossils.
What is a fossil?
A fossil is the remains of a living thing, or the mark it left, kept for millions of years and turned to stone. They can be bones, teeth, shells, leaves, eggs or even footprints.
How a fossil forms
Almost every animal that dies disappears without a trace, because others eat it and time does the rest. A fossil needs a bit of luck. First, the animal must be buried quickly, for example under river mud. Over time, more layers of soil pile on top. Water seeping through carries minerals that slowly replace the material of the bones until they turn into rock. Millions of years later, erosion may bring the fossil into view.
Fossil detectives
Scientists who study fossils are called paleontologists. They work with shovels, hammers and fine brushes so nothing breaks, and they number and photograph every bone. Then, in the lab, they put them together like a huge puzzle. Bones show the animal size; teeth tell whether it ate plants or meat; and footprints reveal whether it walked slowly or ran.
There were many kinds of dinosaurs
Not all of them were giants. Some, like Compsognathus, were about the size of a chicken, while others, like the long-necked sauropods, were more than twenty meters long. Some ate plants and others hunted, and many had feathers.
What happened to them?
About 66 million years ago, a huge asteroid hit the Earth and changed the climate. The biggest dinosaurs disappeared, but a small feathered group survived and its descendants live around us today: birds.
Activity: make your own fossil
Flatten a piece of modeling clay or salt dough, press a shell, a leaf or a small toy into it and lift it away carefully. You will see the mark it left. Impression fossils form in a similar way, although they take millions of years.
💡 Today's birds are descendants of dinosaurs.
