They actually aren't dinosaur; they are a species of pterosaur.
Pterosaurs are ancient flying reptiles that lived alongside dinosaurs. They are commonly mistaken for dinosaurs.
The Pteranodon is commonly called Pterodactyl, which is incorrect, as the Pterodactyl is not a real animal. Although there is a small pterosaur called a Pterodactylus.
The Pteranodon in the game only has three fingers (including a long finger that sticks out from the "hand" to make the wing longer) while the actual animal had four fingers. The Pteranodon in the game also only has two toes on each foot while the real animal had four toes.
It walks by folding up its wings and uses his hands and feet to walk, but this makes it look extremely clumsy. In Club Penguin they seem to fly all the time which is not accurate.