One of the first giants of the dinosaur world was the Dimetrodon. It had a sail on its back made of skin and bones and was an excellent hunter. It even killed prey bigger than itself.
The Dunkleosteus was an armoured fish with a length of eight to ten metres, which was unusually large for the Devonian period. It was one of the first giants of the underwater world, together with the Titanichthys.
The huge, heavy Stegosaurus populated the earth more than 150 million years ago. It had large bony plates on its back, and sharp spikes on its powerful tail.