Dinosaurs were huge animals.

 How did they sleep?

Scientists are trying to find out with the help of fossils.

 Dinosaurs with long necks Sauropod dinosaurs had very long necks. 

They evolved long necks to eat lots of food without moving too much.

 Dinosaurs with long necks may have slept like today's diraffes. 

When giraffes sleep. 

 their necks stay mostly upright. 

Giraffes don't often rest their necks on the ground when sitting. 

Dinosaurs without long necks 

A dinosaurs fossil in Mongolia was found in a sleeping position. 

The dinosaur curled up with its neck and tail wrapping around its body. 

It was the size of a bird.