When a dinosaur died, sometimes the body was washed into a river or lake, where it sunk to the bottom. The skin and muscles rotted away, leaving only the bones, which were slowly buried by mud and sand.

Over millions of years, the mud and sand turn into rock, and the bones become harder and heavier - they are now fossils.

Millions of years later still, the river or lake bed may rise, and the rock gets worn away by rain and wind. The bones are exposed on the surface, and someone may find them, and dig them up. This is how dinosaur bones are discovered.

	This fossil is of a dinosaur jaw. You can see that it is still in the rock. You can even see the teeth at the bottom right.
.	This fossil is of a bird. Because the bones of birds are much lighter than of the heavy animals like dinosaurs, bird fossils are far more rare
	Sometimes the footprints of dinosaurs were preserved in soft mud, and these also became fossils. This tells scientists a lot about how the dinosaurs moved.

(back to top)