Dinosaurs were huge creatures that lived on Earth millions of years ago, long before humans existed. No human ever saw a real dinosaur, but scientists learned about them by studying their fossilized bones found buried in the ground.
Not all dinosaurs were alike. Some were enormous, like «Brachiosaurus», which ate leaves from tall trees thanks to its long neck. Others were fearsome hunters, like «Tyrannosaurus rex», with sharp teeth and a huge mouth. There were also small types, some about the size of a chicken.
Dinosaurs disappeared suddenly about sixty-six million years ago. Most scientists believe a huge asteroid crashed into Earth, drastically changing the climate, and the dinosaurs could not adapt to survive it.
