How do you tell the difference between pteranodons and pterodactyl?

Pteradactyl is actually scientifically named pterodactylus, despite the fact that not many people know this. Pterodactylus lived during the late Jurassic period. It had a long slender head and beak with small sharp teeth. Pterodactylus also had a short tail and webbed fingers.

Pteranodon was larger than the pterodactylus. It was tailless and lived during the cretaceous period. It had a long toothless beak, a bony crest and large wing span.