The way we see dinosaurs in museums and TV shows like Primeval may be all wrong according to scientists.
For years giant dinos like diplodocuses have been shown with long drooping necks, but experts now think they may have held their heads up high instead.
They looked at the way animals with long necks act now, and that's changed the way they think about dinosaurs.
They would have bent their heads down low to drink, but were more likely have them in the air the rest of the time.
The giant dinosaurs were called sauropods as a group, and Dr Mike Taylor said: "Unless sauropods carried their heads and necks differently from every living vertebrate, we have to assume that the base of their neck was curved strongly upwards."
Dinosaur skeletons often have their heads low to the ground in front of them
Another expert, Dr Mike Benton, said as the new theory is based on living animals, computers will now be used to study dinosaur skeletons too.
No change to skeletons
Scientists need to work out if it was comfortable for dinosaurs to carry their heavy heads and necks in the same way as modern, smaller animals.
But Dr Paul Barrett from the Natural History Museum said the diplodocus skeleton there won't be changing any time soon, as it's still posed in a way that the animal could have stood.